Here are some really good equations for determining what gear ratio you may want to concider.
Remember that this is reference only and is based on equasitions from simple math.
Your tire size may be listed as 33/35/37, etc. but the actual measuremnet of the tire could differ once it is mounted on your rim.
Also this write is assuming you have an E4OD, or similar auto tranni.
These are figures that I came up with, to do your own just do:
Circumference of tire divided by the gear ratio you want.
Then compare you answer to the stock forward measurement of 25.5"s and then you will know if it fall over or under.

************************************************** **
Stock 29" tire (235/75R15), with 3.55 gears, 90.7" is circumference of tire, thus for every turn of the drive shaft, you go forward 25.5" or so.

33" tire, 3.55 gears = 103.7" circ, forward 29.2", about 15% more than stock
33" tire, 4.10 gears = forward 25.3" basically same as stock
33" tire, 4.56 gears = forward 22.7", about 11% less than stock

35"s with 4.10s = 26.8, 5% over stock roughly.
35" tire, 4.56 gears, 110.0" circ, forward 24.1", about 5% less

37" tire, 4.56 gears, 116.2" circ, forward 25.5", identical to stock (within error)
37" tire, 4.88 gears, forward 23.8", about 9% less than stock.

38.5" tire, 4.56 gears, 121.0" circ, forward 26.5", about 4% more than stock
38.5" tire, 4.88 gears, 121.0" circ, forward 24.8", about 3% less than stock.

FYI, for those who are thinking they can run a 35" tire with 3.55 gears...

35" tire, 3.55 gears, 110.0" circ, forward 31", about 22% more than stock. That means that your motor is working (and your clutch or torque converter) quite a bit harder to move your truck. That's why it dogs so bad.

If it falls "under" your motor does not have to work as hard to turn the tires, but it does it at a higher RPM. This means that as you go more "under" you lose top end. If it's "over" you'll have a higher top end, but less grunt.
************************************************** **********

Thank you.

Here are some really good equations for determining what gear ratio you may want to concider.
[b]35"s with 4.10s = 26.8, 5% over stock roughly.
35" tire, 3.55 gears, 110.0" circ, forward 31", about 22% more than stock.

ok so with 35's and 4.10s your almost 27% over
but with 35's and 3.55s your about 22% over

SOMETHINGS NOT ADDING UP FOR ME?????? shouldn't 4.10s have a lower percent then the 3.55's??

im sorry for this post between alcohol last night and lack of sleep i came up with this lol :mrgreen: :mrgreen: :mrgreen:

Here are some really good equations for determining what gear ratio you may want to concider.
[b]35"s with 4.10s = 26.8, 5% over stock roughly.
35" tire, 3.55 gears, 110.0" circ, forward 31", about 22% more than stock.

ok so with 35's and 4.10s your almost 27% over
but with 35's and 3.55s your about 22% over

SOMETHINGS NOT ADDING UP FOR ME?????? shouldn't 4.10s have a lower percent then the 3.55's??

Read it again... 35's and 4.10s you're 5% over :)

lol im a fudge up

LOL Its all good.
When i saw that I was like HUH? :confused:

IMO it is the best write up I have seen.

replying before i was done reading again..................... :mrgreen:

:cheers:

READ

READ

Is someone just bored and replying to old topics :roll:

No do your home work and you'll understand.

No do your home work and you'll understand.

yeah i seen the gears post afterword so you bumped it for that guy moon

YUP, Good Catch.

BTT


We still need to make this a sticky

Funny even when you make this a sticky people still have the idea of posting. What are we going to do, this is just one of the many reasons I feel these peoples mothers health plan should have covered abortions.:banghead

:shocked :lolup :lolup :lolup :lolup :lolup :lolup :lolup

http://www.4lo.com/4LoCalc.htm This site give easy to use calculators for the info not listed above.

Now some of us are poor little boys, and can only afford 31's. and I'm still using a C6, so would it be possible for the mad scientist to add 31's to the chart??

how about 33's & 3.73's added to the list too please... :)

Thank you... :brownbag

gobucs posted a calc...try it out. and you have a c6, no overdrive, so your rpm is going to be even higher.

3.73 is pretty much between 3.55 and 4.10, so just estimate.

Here is a gear calculator for you Tomb971 http://www.dfw-tx4wd.org/gears.html try this old to see what you want to run. Stock gears and 33 are not bad try 38's.

Beerman
Here is a good ??? what about these trie size 40's and 44's ?? :shrug

I would say you need 5:13's for a set of 44's and a c6 tranny also with a np 203 or np 205 transfer case. That would put your RPM's at about 2690 @ 65 MPH.

Beerman
Here is a good ??? what about these trie size 40's and 44's ?? :shrug
5.13s. you may be able to get by with 40s, a 351 and 4.88, but 5.13 is going to be better

Thanks cus i wasn't just going to throw on 40's or 44's on a 4.11 gear i have 33's on it now, I was just woundering when i make the change!! Thanks

where did you come up with the data for this post? :shrug

Does your percentage actaully represent how much harder your motor has to work to turn the tire?

It looks more like a percentage differance of how far the tire/wheel turns. comparred to one revolution of the drive shaft.

Does that cross directly over to how much harder the motor has to work?

Now don't get me wrong, I do belive that a motor pushing 44's with 3.08 gears has to work a lot harder than the same with 7.05s.

But what if you had 20" tires and 9.9 gears, it would seem the motor would rev to 8000rpm before you got to 10mph, It would seem to me that motor was working pretty hard.

where did you come up with the data for this post? :shrug

Does your percentage actaully represent how much harder your motor has to work to turn the tire?

It looks more like a percentage differance of how far the tire/wheel turns. comparred to one revolution of the drive shaft.

Does that cross directly over to how much harder the motor has to work?

Now don't get me wrong, I do belive that a motor pushing 44's with 3.08 gears has to work a lot harder than the same with 7.05s.

But what if you had 20" tires and 9.9 gears, it would seem the motor would rev to 8000rpm before you got to 10mph, It would seem to me that motor was working pretty hard.

Its common sense, and a little bit of math, maybe an 8th grade level.
Try reading it again, maybe you will understand better the second time. :twak

Pffff.....while all you tools are doing this stuff with a paper and pencil I prefer to just use this..... http://www.csgnetwork.com/multirpmtirecalc.html :goodfinge

Pffff.....while all you tools are doing this stuff with a paper and pencil I prefer to just use this..... http://www.csgnetwork.com/multirpmtirecalc.html :goodfinge

Ya but do you honestly think most people here know there final tranni gear ratio?
I dont. :brownbag

Hmmm.....yeah, good point. But then again if theyre smart enough to do it with paper and pencil, then by god they should! :wacko

Ya but do you honestly think most people here know there final tranni gear ratio?
I dont. :brownbag



Heheh. 1 to 1 Unless it's overdrive.

:rockon

Heheh. 1 to 1 Unless it's overdrive.

:rockon
:histerica :histerica :rockon

Ok so I now no that I want 4.10's but is this something I can do myself or is this a pro's job. Is there a tech write up somewhere I could not find one.

:beer

Ok, im still confused. If i run my 35's with stock gears, its gonna give me less power and torque? and if i go to 4.1 its better?? :shrug

Gear swaps require a press, setup bearings if you do not have a high priced bearing puller, (clam shell type), a micrometer, a dial indicator, and a copy of the Yukon Gear installation manual. (Randy's R&P has it as a .pdf on their web site). Tolerances are measured in .000 inches. As well as a box full of hand tools and then shop air to torgue the pinion down.


As far as working the engine with 35's and stock gears....it's all about the power band. Your truck looks to do about all it can do before 2700 rpm. It's a truck motor anyways. Your truck engine willl have to increase power to turn the bigger tires. Being a '96, you'd be better off doing the around town driving with the OD off. Your really working the transmission more thean the engine with this setup. Although, a tired engine will also start to show problems as well. Oil pressure loss, overheating, etc.


It's not a BIG issue on the road. Heck, if 90% of your driving is pavement, you'll probably never have a serious problem. Off road obstacles are going to bite you though. Taller tires and stock gears will make the drivetrain work that much harder. You'll be overheating from the start.


Bob K.

Its common sense, and a little bit of math, maybe an 8th grade level.
Try reading it again, maybe you will understand better the second time. :twak

Dude I read it again your right it is common sense, IF YOUR AT AN 8TH GRADE LEVEL. :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge :goodfinge

heycoach Ok so I now no that I want 4.10's but is this something I can do myself or is this a pro's job. Is there a tech write up somewhere I could not find one.

Same question? Anyone got a writeup? Or a good link to a writeup?

If you have to ask, my opinion is dont try it.
By the time you bye all the tools to do the job (press, backlash tool, etc) you could have just drove the axle to some guy and had it done for a case of beer and $100.00

Most of the guys I know here locally will do gears for that price with a smile on their face.

http://www.et-studios.com/motorsports/gears/gears.html

This is another really nice gear ratio calculator!!! :thumbup

I like Randy's calculators cause you can input your gearing if you don't have one of the tranny's listed in the above link. :thumbup
http://randysringandpinion.com/content/calculators/RPM.asp

Here is a gear calculator for you Tomb971 http://www.dfw-tx4wd.org/gears.html try this old to see what you want to run. Stock gears and 33 are not bad try 38's.







I use this one. :thumbup

You could also add VIN codes for axles to this as well. eg. under "axle" on your door's VIN sticker "H9" is 3.55's with a limited slip, "C5" would be 4.10 with a limited slip. This could help when searching the local wreckers.

Also this write is assuming you have an E4OD, or similar auto tranni.

So how off would this figures be for those running a ZF 5 speed?

James

I use this one. :thumbup

This one is great... except they don't list my T-case... :wacko

Sorry, for a zf 5 speed you will hve to figure out what your rpm band range is now, then do the math listed for each gear. once you have that then you will know your overall rpm range for 5th gear

My inside door sticker says the stock tire size is 265/75R15. Roughly 30.6 inches tall. So 4.10s with 35s will be about spot on.

.....
Circumference of tire divided by the gear ratio you want.
....
33" tire, 3.55 gears = 103.7" circ, forward 29.2", about 15% more than stock


Now my 8th grade math class taught me that circumference was 2*pi*r. So...

EDIT: Removed my strange math.

EDIT: Ha ha. Except that tires sizes are diameters and I was forgettig the 1/2 first that made it SEEM like the 2 was missing from the equation. :histerica

but, once you get larger tires moving does it require any more power to keep them moving than small tires? or is it just about the same difference?

A smidge. Bigger tires have a little more rolling resistance. It's small enough that you can pretty much neglect it, though.

Re-gearing makes it easier to turn the big meats, however stopping the big meats is another issue

hmmm, I've found that stock brakes work pretty decently with 33's. I don't ever really put myself in situations that require really quick stopping though.

Hi all

I am Lifting my 1991 FSB and and installing 35 inch tires.
Not using it for off road; the only time I will engage the front is in stuck situations.
So for those of you who have successfuly done this the gear setup
what is the ideal gear ratios for the front axle and rear axle.

Currently the front is 3.54 and don't know what the rear is

thanks

Stock, the front will be the same as the rear. For a daily driver, I'd recommend 4.10s, because its darn near the same overall as 31" tires and 3.55s, which is what mine came with. 4.10s and 35s can get me 16mpg highway if I keep it at 65 on a good day.

Stock, the front will be the same as the rear. For a daily driver, I'd recommend 4.10s, because its darn near the same overall as 31" tires and 3.55s, which is what mine came with. 4.10s and 35s can get me 16mpg highway if I keep it at 65 on a good day.
:stupid 4.10's / 4.11's should be perfect for you.

HI

jeff's Bronco Graveyard has 4.09 front and 4.11 rear
ring and pinnion will that do

do you need a bigger housing or just change the ring and pinnion

lou

You are gonna have to get a new carrier for the front. (not a housing) About $50 for open, more for a ltd slip/ locker. The rear is fine, just put the gears in.

thanks

I will need to do this job

there is great write up for the rear 8.8
any one know for the front if there is a rebuild write up

I searched but could not lacate any

thanks

Lou

My stock FSB 351w is 31" with 3.08

I want to go 35" with 3.54

They are the same ratio but is it enough for the 35" or is it better going to 3.73??


Why in USA a lot of people go 4.11 / 4.56 ??

Stock gears are 3.55's...the gear of choice for 35's is 4.45 and for 33's is 4.11...me, I got 25's and stock gears...

My stock FSB 351w is 31" with 3.08

I want to go 35" with 3.54

They are the same ratio but is it enough for the 35" or is it better going to 3.73??


Why in USA a lot of people go 4.11 / 4.56 ??


The 4.11/4.56 gearings allow for your motor to turn the 35" tires just as easily as if the bronco was driving on the stock tires. If you try and put on 35" tires with 3.54 gears you are going to get poor gas mileage and it will be much harder on the engine getting the vehicle up to speed. You will also not have any low end "grunt" when trying to crawl up rocks or steep hills, or even just getting up to speed on the highway.

Good Luck
And welcome to FSB, I don't think we have many members from Belgium:beer

Old Yeller

First off, a very handy tool one of the other guys here linked up the other day ... excellent rpm calculator for various gears, transmissions, tires, and transfer case combinations (http://www.balsa.no/bil/calcs/gearcalc/). It's the quickest and cleanest tool I've seen yet for checking engine speed for different conditions, plus the owner of the site has been very quick to add different transmissions on request.

Second -- usually your primary concern with gearing is getting your operating RPM where you want it to be at your usual cruise speed. This has a huge effect on both economy and acceleration. Most of the engines used in the Bronco will get best economy if they're turning around 1700-2000RPM at cruise, from what I've seen. Too low and you fall out of the powerband (and efficiency band) of the engine, and too high you lose too much to friction losses at cruise.

With your current gearing, 31's, and non-OD tranny, you're right about there with your current combo -- about 2000rpm at 60mph. Keep in mind, though, that a lot of the guys with slightly later trucks have an overdrive tranny, and get about the same operating RPM with 4.10's and overdrive, on the same tires.

hem...
my axle code is 18 = 3.08
at cruise 65 mph = 2300 rpm.

It's C6 but non AOD. Chuck is maybe right with his explanations about AOD. In Belgium everybody cruise at 75 mph.

3.55 will fit good due to the same ratio or I put 3.73 due to the extra weight of wheels and tyres??


I think I'm the only one from Belgium. :beer Because we are plenty of beer in Belgium.

Stella Artois is a Belgian beer right?

There are a lot of breweries in Belgium for sure,
I would personally go with the 3.73's out of your two choices, but then again, if it were me I would go with the 4.11's. But that's because I use my rig primarily for towing and the trail. I don't cruise the highway in it daily so I didn't build it based on what Rpm's i'd run on the highway. What it comes down to is what you use your bronco for the most. Do you go offroad alot, or do you use it mostly for driving 75 on the highway?

The most popular beer in Belgium is Jupiler. But we have a lot of special beer, 400 and more..

I use on highway and offroad.
I want to keep the same rpm.
The engine 351W is torky engine isn't?

What do you prefer for your ring?

http://store.summitracing.com/default.asp?Ntt=pinion+ring&searchinresults=false&Ntk=KeywordSearch&DDS=1&N=115&target=egnsearch.asp

Tell me what's the best quality but not too much for my FSB 35'...

Try this chart from Jefff's Broco Graveyard catalog. http://www.supermotors.org/getfile/280159/fullsize/100_3392.jpg

I thought I'd add a little real world info.

I installed 5.38:1 gears yesterday. I took a quick 2 mile run down the hiway moments ago to see what my rpm's would be like at 65 mph(mph measured with a GPS unit). Here's what I got:

Trandmission - e4od
Axle - Sterling 10.25
Gears - 5.38:1 Yukon
Tires - 38.5 x 14.50 x 16.5 TLS SX
Actual tire height - 36.5" (tires at 1/2 tread or so)
PSI - 25
Speed - 65 MPH
RPM's - 2400
Bling factor - can "cherp" the tires from a stop
Estimated milage - 6MPG city or hiway/3 gallons per mile in 4 low

First off, a very handy tool one of the other guys here linked up the other day ... excellent rpm calculator for various gears, transmissions, tires, and transfer case combinations (http://www.balsa.no/bil/calcs/gearcalc/). It's the quickest and cleanest tool I've seen yet for checking engine speed for different conditions, plus the owner of the site has been very quick to add different transmissions on request.

Is it me or are the HI / LO backwards? The colors on the graph? Says LO is faster than HI...

Is it me or are the HI / LO backwards? The colors on the graph? Says LO is faster than HI...
I know he does a lot of tweaking on the calculator, he may have flipped colors on something by accident ... I hadn't been paying attention to the range colors, so I hadn't noticed.

how would one know what the gear ratio in an axle with no tag or vin code? (9inch from a 78 or 79 ford PU) supposedly the axle has the stock running gears but that could be several, i remember a thread awhile back about counting rotations of the driveshaft whille spinning the tires.....but searched an couldnt find it. am i just gonna have to pull the carrier?

ive had it in 4wd in deep mud with 40's an it never gave me a prob, but i have smaller tires now an im driving on the street more. if it snows i wanna have 4wd an light trail use but dont wanna break anything till i know for sure. im guessing 3.50 an compared to the 3.54 in front i dont think i should have that much of a problem.

i wanna be sure though, Thanks for any help i could get.

No problemo. Method differs slightly depending on whether it's open or limited slip, so that's the first thing you check. Chock the front wheels and lift both rears off the ground, but leave it in park or in gear. Try to turn one wheel forward. If the other wheel turns backward easily, it's either open or a very worn out lsd. If it won't turn (or takes at least about 30lb-ft minimum to turn), then it's limited slip.

Now, with that out of the way, here's how you check the ratio for each.

Limited slip: Leave both back wheels off the ground, put transmission or transfer case in neutral. Use chalk or a crayon to mark the driveshaft and a spot on the tire. Rotate the back wheel forward, and count the number of full rotations as w. Have a friend count the number of full rotations of the driveshaft, and call that number d. Your gear ratio is d/w. You can get away with only rotating the wheel a couple of times, but the more rotations you count, the more accurate the results. For instance, I usually prefer about w=10, it's big enough to be accurate but makes for easy math. With my 3.55's, that means the driveshaft turns 35 and 1/2 times -- enough turns that you can actually tell the difference between a 3.50 and 3.55 ratio by whether or not the shaft makes that last half turn. If you only turn the wheel twice, you get 7.1 turns on the driveshaft. Can you really eyeball 0.1 turns accurately? If you counted 7 turns on the driveshaft, you'd get 3.50, but it's still "close enough" if you just what a rough idea of what a vehicle has.

The procedure for an open diff is very similar but just as simple. Put the tranny in neutral, but put the opposite wheel down on the ground. When you turn your wheel, since the other wheel is still, the diff will turn half as many times. This throws a factor of 1/2 into the formula. Again, counting w (wheel revolutions) and d (driveshaft revolutions), your gear ratio = 2*d/w. I usually use 20 turns of the wheel when I want to be accurate with an open diff. For my 3.55's, that means 20 turns on the wheel (with the other wheel on the ground) would give me 35 and 1/2 turns on the driveshaft again.

The cliff's notes:
Count w = number of wheel revolutions, d = number of driveshaft revolutions
LSD: Both wheels in the air, ratio = d/w
Open: One wheel on the ground, ratio = 2*d/w

Thanks!!! :beer

I know he does a lot of tweaking on the calculator, he may have flipped colors on something by accident ... I hadn't been paying attention to the range colors, so I hadn't noticed.

That was a small bug, sorry for the inconvenience.
I really appreciate feedback so I can make this little tool better.
Just let me know if something is off or missing.

Realistically what can I expect to pay to have my bronco regeared from 3.5 to 4.56?

If I had all the parts what would/should the labor cost roughly?

Realistically what can I expect to pay to have my bronco regeared from 3.5 to 4.56?

If I had all the parts what would/should the labor cost roughly?

If the axles were out, ~$125-225 per axle. If they are in, it could double. This will vary with the part of the country. If you search, you may find info on this since it has been discussed from time to time.

BTW, when using this calculator

http://www.et-studios.com/motorsports/gears/gears.html

Use these gear ratios for the E4OD

1st = 2.71
2nd = 1.538
3rd = 1
4th = .712

If I currently have stock gears in my 96 bronco dana 44 front 8.8 rear w/ stock gears and I want to chane my gears to 4.56s will i need a new carrier for both axles?

If I currently have stock gears in my 96 bronco dana 44 front 8.8 rear w/ stock gears and I want to chane my gears to 4.56s will i need a new carrier for both axles?
Just the front.

But if your 96 has the limited slip in the 8.8 you will need to get an open carrier for it. I got mine out of a junk yard.

But if your 96 has the limited slip in the 8.8 you will need to get an open carrier for it. I got mine out of a junk yard.

Why?

just the front okay great thanks--

Why?

My brain stepped out for a moment. For some reason I thought he was going to use a luckbox locker.:doh0715:

I'm an idiot.:toothless

O.K.
let me throw this out there because it hasn't been asked it and that is probably because I am the only idiot to think it.

Right now I am running stock gears (I think) with my 33's. I am getting around 7-9 MPG. I actually get worse milage on the highway. The question is, according to this chart I am getting worse fuel milage and power because I am 15% over. If I change to 4.10 gears, I am even and will be getting stock gas milage. If I put 4.56's in with the 33's I will be 11% under. Will I get better than stock gas milage?

I dunno.:cry

If I put 33 inch tires on my bronco....it has a gear ratio of 3.55 ,E40D, do I need to regear. Also on my diff, it says 3L55 does that mean I have a locker? I replaced my diff to a str8 355 because the one that said 3L55 broke on me! And also, when I do a 2 Inch lift, what besides the lift components is required for the whole setup to be a sucess? And If I need to regear, or convert my diff to a locker, does anyone know a website where I can purchae locker components so I can rebuild my whole diff?
Let me know and preferably email me...
sohaggard88@aol.com

Hmmmmmmm........... what a lot to take in!!

Ok, so o've just put 35's on my bronc and she definatly labours like f**k now on the road, whereas before she'd show these damn rice racers a good fight.........for about a nano-second!

My points are thus;

if i re-gear to 4.56, will i get the same gas milage as surely she'll be doing a lower MPH at the same RPM in the same gear, so therefore i would have to have a higher RPM to achieve the same speed in top (which i probably wouldnt be able to achieve!)

Secondly, whats a locker and do i need one?? (i'm from the uk, sorry!!)

Thirdly, where do i get these gears from cos everywhere i'm checking seems to ask for my vehicle year then tell me i can only order stock!!

Forthly, i've searched this site and cant find how to do it, now thats not such a big problem if you live in the US but over here in the UK, not everyone swaps axles on their mini's you know!

Fithly, do i need any extra parts for my axles or wil it all come in a kit and thats that?

And finally, i am planning on boosting my engines BHP (finances permitting!) so what happens to my top speed etc then? is it going to be constrained by the gearing and should i re-gear down again to benefit both acceleration and top speed?

try completeoffroad.com

I wish that people still read this - we will see I guess. I was reading the initial post and also I checked a few of the calculators out. There is one large flaw that I see. It seems everyone is using their nominal tire height to base these numbers. That is not the actual height of the tire, thus the circumference is not accurate. The number that needs to be used is tire revs per mile, which can be calculated from rollout. Using the numbers from the first post, a stock tire turns 698 times per mile, when tire specs for a 235-75-15 usually hover more around 715. Also, 35 in the first post turned 576 times per mile, while manufacturer specs are normally right at 600. If you notice, the error in those two numbers goes in the opposite direction. By the way, to deduce numbers from the first post numbers I multiplied inches traveled x gear ratio / 12 (to get into feet) and then divided 5280 by that number.
Now if you use rollout/rev per mile the numbers come out quite different.

3.55s and 235s = 24.96 inches per turn of the driveshaft.

4.10 and "35"s = 25.75 inches per turn of the driveshaft

so while yes, this does mean that 4.10s and 35s achieve slightly more ovedrive than stock, it is VERY slight. Changing the overdrive from .71 to .70 would make more difference (25.24) A "normal" 35 inch tire with 4.10s is the closest you can get to stock. This does not take into account additional rotational mass or additional air resistance. I suppose if you wanted to gear lower than stock (similar to going to 3.73s with stock tires) you would want 4.56s (or don't forget the 4.27 ratio). Also, if you call 31s stock, then 4.10s and 35s would leave you geared slightly deeper than you were.

So in my case, with a 35 and 4.10s, at 60 mph, I would be turning right at 1750 rpms.
(1750 turns of the motor will turn my dshaft 2460 times (.71 OD in e40d) which with 4.10 gears will turn my wheels 600 times (2460/4.10) and 600 turns of my 35 = one mile.)

All this stems from the belief that many on this site seem to have that 4.56 and 35s = stock. I am very aware that it is not a bad combo that gives good power and might even affect mpg around town, but it is not stock. I am happy power wise with my truck with 35s and stock gears, so the boost from 4.10s = bonus. On the highway, you will be hard pressed to convince me that 4.56 will get better fuel mileage than 4.10 (with 35s) The engine (my engine in my truck anyways) has adequate power, so 4.56s would just turn higher rpms, which ask any over the road trucker = lower mpgs. Also at 70 and 75 with my setup you would be looking at just over 2000 and just under 2200 rpms, respectively. Sorry for the long windedness, I just hate seeing inaccurate info being regurgitated as the gospel truth.

. . . I suppose if you wanted to gear lower than stock (similar to going to 3.73s with stock tires) you would want 4.56s (or don't forget the 4.27 ratio). Also, if you call 31s stock, then 4.10s and 35s would leave you geared slightly deeper than you were. . . .



The problem is that there are no reverse cut gear sets available for the D44. It would be possible for the TTB D44 guys to us a D50 center section but not likely worth the trouble unless they happened to have one laying around.

can you go wrong with high gear ration even if your tires arent that big. im going for 35" tires and i saw 4:88 are as much as 4:56 so would it be fine just to get the 4:88 and if so would it help my gas any should i stick with 4:56

I'm not one for asking dumb questions, but goddammit, I just can't find a definite answer.

The gear ratio for the front will be different than the rear axle correct? If I want to run 4.11's in the rear, I get 4.09's for the front diff right? I thought I could look on my own axle, but the tag for the front ain't there. My rear axle is 3.55 stock, so that should mean that my front is around 3.53?

I also read in here that to run 4.09's in the front diff, I'll need a new carrier? Why?

your front is probably 3.54. Dana axles have carrier breaks. That's just the way the way Dana designed them. The break for the D44 is 3.92 and numerically higher. There is no reverse cut in 3.92 though so 4.1 is the next available ratio in reverse cut for the D44.

Sometimes the front and rear are exactly the same, 3.73/3.73 and 3.50/3.50 are some examples with the latter being a 9" and D44.

your front is probably 3.54. Dana axles have carrier breaks. That's just the way the way Dana designed them. The break for the D44 is 3.92 and numerically higher. There is no reverse cut in 3.92 though so 4.1 is the next available ratio in reverse cut for the D44.

Sometimes the front and rear are exactly the same, 3.73/3.73 and 3.50/3.50 are some examples with the latter being a 9" and D44.

Wow...I'm totally lost. WHat is a carrier break?
Are you saying that to run gears numerically higher than 3.92, I need to get a 4.10 carrier? We're not talking about the housing right?

Wow...I'm totally lost. WHat is a carrier break?
Are you saying that to run gears numerically higher than 3.92, I need to get a 4.10 carrier? We're not talking about the housing right?

No its not the housing but the carrier. You need one for the 4.10 (or 4.11).

Ok...gotcha. I went to Bronco graveyard and I see what you meant. Thanks!

I'm running a 460 (450 hp modified) with a C6 trans I just purchased Dana 60's with 4.10 gears. Tire size I want is 40" . But with this combo and lockers if I put the truck up against a 2 foot high ledge is it going to power out or climb right up? Going up to 4.88's makes everything more expensive lockers are more ...Anyone running this combo?

With 450 horses, and I am guessing that the torque is close to that, you should be okay. But if it were me I would do the 4.88's now if the locker is going to be different. I am not sure about this so others may be can correct me if I am wrong.

:thumbup i have an 86 bronco with a 302, AOD and a BW1356(or what not) tcase...
i will be running 35's for a while would 4.56 get better mileage than the stock 3.55s. i am not really worried abot off road yet till i do my 1 ton swap
thanks much

in town maybe - on the highway prob not - depends on how fast you drive.

didn't really help out my mileage

thanks, would 4.88s be better then?? or 410

thanks, would 4.88s be better then?? or 410

4.88 would be o.k. since you have the OD. If you have an 8.8 rear, you may want to go with a newer carrier because earlier 8.8 carries had a smaller cross pin. Also use a solid spacer rather than a crush sleeve on the pinion.

it will prolly be a 14bolt but i do have 4.88s for an 8.8 i could use, why a solid spacer rather than a crush sleeve, and the carrier i have has the 7/8 cross pin isnt that the big one

it will prolly be a 14bolt but i do have 4.88s for an 8.8 i could use, why a solid spacer rather than a crush sleeve, and the carrier i have has the 7/8 cross pin isnt that the big one

If you are using big tires they can crush the crush sleeve more which can damage your rearend. The solid sleeve eliminates that possiblity.

The 7/8 cross pin is the big one.

I have an 88 f150, 302 with 4" lift and 33's(12.50). I want to do gears, but would 4.88 be too much? Currently i have an AOD, and never use the overdrive, and do a lot of in town driving. Soon will be swapping in a C6. Will 4.88's be too much? During hunting, I drive 10-20 miles a day highway, will the 4.88's really kill my gas mileage?

-Josh

4.88's with 33's and a C6, will most definitely hurt your gas mileage.

Taking away an overdrive/lockup converter transmission will hurt your mileage to begin with. Then 4.88's which are definitely overkill for 33's, will hurt it. 4.10's are plenty for 33's.

With a C6, 4.88's, and 33's, you'll be lucky to do 60mph, at like 3800rpm or something.

But it'll be faster then shit off the line.

:stupid maybe 4.56's but 4.88 will kill you with only 33's. If you are going to get bigger tires, then that would be different.

so would driving 35" tires with 4.10 gears give you better gas mileage than if you had 4.56s? or is it the other way around. i know 4.56s would give you more grunt...

I just got done reading this thread for probably the third time and each time I just get more and more information. This summer I will be running 33's with a 4 inch lift, and I was wondering if there will be that much of a difference by running stock gears? I will be mostly on the pavement but the occasional mudding every few months or so. Thanks for the help

so would driving 35" tires with 4.10 gears give you better gas mileage than if you had 4.56s? or is it the other way around. i know 4.56s would give you more grunt...

you would get better gas mileage with the 4.10 gears because your rpm range would be lower.

you would get better gas mileage with the 4.10 gears because your rpm range would be lower.

but it would be slower off the line? seems like in my situation that would be the better gear to go with 35s since id be driving my bko everyday and on the freeway a lot.

thanks scott!

ok, i can't find the site i used before to determine correct gear size for 33's. stock size on my Bronco is 265/75 15's (30.6 in tire). i think it was something like a 4.06 gear but i think i calculated that for 235/75 15's (what is currently on my Bronco) before i realized that those tires weren't the stock size.

any help?

oh and the door jamb axle code is 19

wow this was really helpful i am glad i researched ~!

Okay so im running 33's on 3.55 gears ATM. I think i might upgrade eventually to 35's. Based on the informatin i read in this thread the best thing for me to do with what i use my bronco for would be to:

A. If i stick with 33's i should eventually upgrade to 4.10 gears for maximum performance,the best gas milage possible, and to put the least amount of stress on my engine/tranny.

Or

B. If i upgrade to 35's then i should install 4.56 gears for the same overall performance as the 33's and 4.10 gear setup as stated above.

Now, what if i want the best combination of highway/city driving and offraod performance and i upgrade to 35's? Would 4.10's give me the best RPM range and gas milage on the highway and still get me through the rough shit on the trail when running 35's or will 4.56 gears be a better gear for this application?

4.56 gears and running about 65 miles an hour will yield the best mileage results.

4.10s and 35s will make your city mileage suffer compared to 4.56, and will only gain about .5 mpg on the highway. Not to mention, you will regret the 4.10s every time you start up a steep hill...

thanks hopper, i was wondering this too.



4.56 gears and running about 65 miles an hour will yield the best mileage results.

4.10s and 35s will make your city mileage suffer compared to 4.56, and will only gain about .5 mpg on the highway. Not to mention, you will regret the 4.10s every time you start up a steep hill...

honestly its a toss up, I tow trailers up hills with 4.10s and it goes just fine, I also cruise at 70 with decent mileage. And on the trail just throw it in 4lo and forget about what gears you have. Keep in mind that when your 35s wear down to 75-50% tread, your gearing will be exactly stock with 4.10s. Either way its better than 3.55s though.

I got a C6 in my 89 and im running 35's.

Most people say go with the 4.56's, but since i have no overdrive would i want to go with 4.10s? I was pullin 3k RPM at about 75 mph on the freeway, so how fast would i be able to go with 4.56's?

Also, is it ok to run at 3k RPM constant like that?

You want 4.10s at most Bonzai. 4.56 would be way too deep with no OD. I don't like to run the engine over 2500 RPM for extended periods of time, but I'm really easy on it...

What gears do you have? You should be running about 2700 or so RPM at 75mph.

You want 4.10s at most Bonzai. 4.56 would be way too deep with no OD. I don't like to run the engine over 2500 RPM for extended periods of time, but I'm really easy on it...

What gears do you have? You should be running about 2700 or so RPM at 75mph.

i got 3.55s...i think. I bought the truck 2 or so years ago and for the most part i dont know whats in it from the previous owner. But im pretty sure the previous owner ran 35's, so i wonder if he bothered to regear...

My K&N is completely CAKED with mud, im wondering if thats making the engine work harder??

According to my calc:

~2700 RPM @ 75 w/3.55s

~2900 RPM @ 75 w/3.73s

~3200 RPM @ 75 w/4.10s

Does it feel gutless around town? Is your speedo correct? It might have 3.73s...

4.56 gears and running about 65 miles an hour will yield the best mileage results.

4.10s and 35s will make your city mileage suffer compared to 4.56, and will only gain about .5 mpg on the highway. Not to mention, you will regret the 4.10s every time you start up a steep hill...

So if i run 35's and i will be mostly city or trail driving and not so much highway i should go with the 4.56 gears?

How will 4.56's affect my city driving?

Will they out perform the 4.10's on the trail if running 35's?

So if i run 35's and i will be mostly city or trail driving and not so much highway i should go with the 4.56 gears?

How will 4.56's affect my city driving?

Will they out perform the 4.10's on the trail if running 35's?

If you're doin mostly city, go with 4.56s, it'll be a tad quicker in town, and a little easier to handle on the trail.

Yes, I believe that 4.56 is better than 4.10 all around with 35s.

4.56s will be better for city driving. The lower gears will improve acceleration, and the engine will not have to work as hard which will improve city mileage.

Lower is better for the trail.

If you're doin mostly city, go with 4.56s, it'll be a tad quicker in town, and a little easier to handle on the trail.

Yes, I believe that 4.56 is better than 4.10 all around with 35s.

4.56s will be better for city driving. The lower gears will improve acceleration, and the engine will not have to work as hard which will improve city mileage.

Lower is better for the trail.


Thanks guys, that answers all my questions for now. Much appreciated:thumbup

According to my calc:

~2700 RPM @ 75 w/3.55s

~2900 RPM @ 75 w/3.73s

~3200 RPM @ 75 w/4.10s

Does it feel gutless around town? Is your speedo correct? It might have 3.73s...
speedo is correct. I COULD possibly have the 3.73's if those numbers hold true to my truck.

I dont do the freeway often, maybe 5% of the time, would it still be smart to do 4.10's over the 4.56's?

4.56s would put you at 3300 RPM @70. That's waay too high. If you never got over 60 mph or were thinking of bumping to 37s, 4.56s wouldn't be such a bad thing.

I would go with 4.10s if you really want to gear down some more. If the truck already has 3.73s, it won't really be worth it, IMO.

So, what gears came stock on a 88 XLT 8.8 with C6?

I gotta be honest...I think I'm more confused now than I was before I read this thread. So 4.10 gears -are- better for a 302 pushing 35s with an E4OD than are the stock 3.55s, right? Regardless of whether you're off road or on, the 3.55s just ain't cutting it, at least not in my Bronco. Honestly, I know barebones working under the hood, and I know jack about working on transmissions and differentials. Right now, with basically everything stock except my tires and lift, you can barely call what I do accelerating, and it just feels powerless. Should I go with 4.10 in front and back, or 4.56, or what? Most of my driving lately is city with some highway. I don't even know where I can go off road around here, but it -will- go off road again. What should I do?

4.88's.

what is the scoop with regearing the front? Do you need to get a new carrier or explain to me how this works.

Stan

Yes you will need a new carrier. The D44 has a break at 3.92 and up. So a new carrier, gears, and an install kit.

While your in there might as well do the d-50 stub shaft.

I just went through a gear install on the 8.8.

I got used gears that were in great shape and set up properly the first time. The install kit was a yukon master install and I got a solid spacer to go with it. I got the master install for $80 and the spacer was $20.

I paid $390 in labor and that included the gear install, some necessary grinding on the ring gear, outer axle bearing, wheel seals, and the entire inside of the axle thoroughly cleaned. I also have to pay for those parts and the gear oil. Installing the solid spacer as opposed to the crush sleeve required more setup time and hence the labor went up slightly. IMO it was money well spent.

I am running 4.56:1 gears w/ 35's and at 64mph (GPS) I'm at 2,000 RPM's. It drives better than it did w/ 3.55's with 32's. I'm VERY pleased that I chose 4.56:1 gears as opposed to 4.88's.

As for the used gears, so far so good (although I have very little driving on them). The only time I get any noise is when I let off the gas at 30mph and even that is very minimal.

I just went through a gear install on the 8.8.

I got used gears that were in great shape and set up properly the first time. The install kit was a yukon master install and I got a solid spacer to go with it. I got the master install for $80 and the spacer was $20.

I paid $390 in labor and that included the gear install, some necessary grinding on the ring gear, outer axle bearing, wheel seals, and the entire inside of the axle thoroughly cleaned. I also have to pay for those parts and the gear oil. Installing the solid spacer as opposed to the crush sleeve required more setup time and hence the labor went up slightly. IMO it was money well spent.

I am running 4.56:1 gears w/ 35's and at 64mph (GPS) I'm at 2,000 RPM's. It drives better than it did w/ 3.55's with 32's. I'm VERY pleased that I chose 4.56:1 gears as opposed to 4.88's.

As for the used gears, so far so good (although I have very little driving on them). The only time I get any noise is when I let off the gas at 30mph and even that is very minimal.

Stang thanks for that update. Just what I need to read. Couple of questions here for you. Was your axle under the truck when you had it regeared or was it free from the truck. Looking at regearing when I do my SAS and was thinking I would just remove my axles when I get them regeared.

I like the way your rpms are sounding. It seems like at 70 would should be in the powerband of the engine. I am like you trying decided between 4.56's and 4.88's. Sounds like the 4.56's are the way to go if it sees the interstate.

The sound you hear will go away once everything is broken in.

Stang thanks for that update. Just what I need to read. Couple of questions here for you. Was your axle under the truck when you had it regeared or was it free from the truck. Looking at regearing when I do my SAS and was thinking I would just remove my axles when I get them regeared.

The axle was in the truck. I didn't have time to mess with it. If I did, I certainly would have pulled it. A few shops quoted me $150 in labor (just for gears) if I pulled the axle.

I like the way your rpms are sounding. It seems like at 70 would should be in the powerband of the engine. I am like you trying decided between 4.56's and 4.88's. Sounds like the 4.56's are the way to go if it sees the interstate.

I was very worried that after I got this done, I would wish I went with 4.88's but I am extremely satisfied (thus far). I really think 4.88's would be too much gear.

Thanks stang.

That helps out a lot. I was worried about going to 4.56's also seeing as I have the 302 (although I have a complete new motor now) and thought that with all the extra's like tires, lift, bumpers, etc that the 4.88's would be better to get it rolling. I see that you have the 302 also so I may just go 4.56's then.
Thanks

Don't get me wrong, I still know that I'm driving a fat, underpowered, pig of a bronco on 35's....but I don't expect it to haul ass no matter what gears are in it.

Maybe someone with 35's a 302 and 4.88's can chime in.

I dorve an F150 with 302 and 36 inch tires with 4.88s and that is what sold me roms are good at 70mph, more power, just all around good for me. but hey if you are happy cool deal. i got a friend with the 5 speed and he said 4.56 is good for him but if he had the e4od he would have gone with 4.88s as well. he is thinking of redoing his

I will be referencing this when someone tells me I've never contributed to FSB! I received it in print at work and was happy to find a digital version.
Please read the fine print. If you physically can't, ask me for high resolution version.
http://img301.imageshack.us/img301/9861/gearratioguidesizedhk7.jpg

BTW, I've ordered 4.88s!

Man, I hate asking questions. Here it goes anyway. I have a stock 86 I picked up a few months ago. It was a 6 cyl. Bronco with a np/435. 8 inch rear. I put a 9 inch rear,351w,and c-6 out of a bone stock 85 Bronco in it. Now that I've been looking at gears for my 94 I notice they are selling 355's for a 8 inch, and 350's for a 9 inch. Did I screw up, because I would guess that stock my d44 has 355's in front.I don't even have the front shaft in, but now I'm a little nevous about them not matching. I hope I didn't f up on this one.

I will be referencing this when someone tells me I've never contributed to FSB! I received it in print at work and was happy to find a digital version.
Please read the fine print. If you physically can't, ask me for high resolution version.
http://img301.imageshack.us/img301/9861/gearratioguidesizedhk7.jpg

BTW, I've ordered 4.88s!

is aw that too. now knock about 15-20 percent of that off due to yhour overdrive tranny.

Hey guys. I am thinking of getting a complete third member with the power lock, 4.56's from bronco graveyard. Does any one have any input as to any one who may have a better deal than $825.00. I've added things up and it doesn't sound like a bad price. And all I have to do is put it in. I'll do the rear myself. I really just don't want to mess with the 44.
The 8.8 rear is going to be Yucon 4.56, master rebuild kit, notched cross pin, pinion setup bearing and new ring bolts are $397.00, my rebuilt trac lock is fine. Can anyone beat that price?
I don't think any one else sells complete 3rd members do they? And has any one bought one of these from BG and know the quality?

Thanks for any info you may have, Steve

Don't get me wrong, I still know that I'm driving a fat, underpowered, pig of a bronco on 35's....but I don't expect it to haul ass no matter what gears are in it.

Maybe someone with 35's a 302 and 4.88's can chime in.

I'm running 4.88s in my 302 96 bronco, I wish I even had gone to 5.13s as I have no problem at all for highway driving, I could have afforded a few hundered more RPMs to the 5.13s.

I was very worried that after I got this done, I would wish I went with 4.88's but I am extremely satisfied (thus far). I really think 4.88's would be too much gear.

Not too much at all, I'm running 35s and 4.88s. truck works great and I drive it to work all the time.

I'm running 4.88s in my 302 96 bronco, I wish I even had gone to 5.13s as I have no problem at all for highway driving, I could have afforded a few hundered more RPMs to the 5.13s.

Not too much at all, I'm running 35s and 4.88s. truck works great and I drive it to work all the time.

Thanks for chimming in Boss. Thats some helpful info there. I wanted to hear from someone that had them. I dont want my engine to scream but I still I want to be able to get out of it's own way. :thumbup

Off the top of your head do you know where your Rpm's are at 70. That seems to be where my problem is. Going down the Highway and wanting to pass someone at 70 doesn't happen all that fast for me. :doh0715:

i have 37's and a 300, my front already has 4.88s and my rear has 3.55's. i really wanna do 5.13's but i dont think i can justify spending another 500 on the 44. whats yalls thoughts?

i have 37's and a 300, my front already has 4.88s and my rear has 3.55's. i really wanna do 5.13's but i dont think i can justify spending another 500 on the 44. whats yalls thoughts?

Right now your setup is useless - install 4.88s in the rear and get a couple years out of it.

Right now your setup is useless

well of course it is. the gears dont match. what i was saying is would it be worth it to install 5.13's all the way around. are they goin to be that much better than the 4.88's?

no. run 4.88's and be happy.

Thanks for chimming in Boss. Thats some helpful info there. I wanted to hear from someone that had them. I dont want my engine to scream but I still I want to be able to get out of it's own way. :thumbup

Off the top of your head do you know where your Rpm's are at 70. That seems to be where my problem is. Going down the Highway and wanting to pass someone at 70 doesn't happen all that fast for me. :doh0715:

I would just go one number at a time. 4.88 is a massive jump. Give 3.73 a try. I am going to 3.73 with 32" and small lift. I think it will pay off nicely. 3.66 is what I calculated to return to stock for me, so 3.73 will add a small cushion without burning the engine at 2400 rpm in od at 55. Right now it takes so much pedal to keep it at 1800 rpm at 55 I am loosing big time.

just my opinion.

I would just go one number at a time. 4.88 is a massive jump. Give 3.73 a try. I am going to 3.73 with 32" and small lift. I think it will pay off nicely. 3.66 is what I calculated to return to stock for me, so 3.73 will add a small cushion without burning the engine at 2400 rpm in od at 55. Right now it takes so much pedal to keep it at 1800 rpm at 55 I am loosing big time.

just my opinion.


Why would you want to regear the truck more than one time. To me that is an expensive job and I only want to do it once. I know 4.88's may be a little much for 32's but my plan is to run 35's. I just dont want to pay to regear my truck twice. But thats just me. That is also the reason why I am trying to decide b/w 4.56's and 4.88's. If you are going to keep the 32's the 3.73's would be nice and you could probably find a JY axle to use. I am just building for down the road.

:beer

Why would you want to regear the truck more than one time. To me that is an expensive job and I only want to do it once. I know 4.88's may be a little much for 32's but my plan is to run 35's. I just dont want to pay to regear my truck twice. But thats just me. That is also the reason why I am trying to decide b/w 4.56's and 4.88's. If you are going to keep the 32's the 3.73's would be nice and you could probably find a JY axle to use. I am just building for down the road.

:beer

You'll have a ball with 4.88s and 32s, its not that big of a jump - maybe 600rpm. When I ran 4.10s and 33s I was upset with myself for not going to 4.56s, 4.10s gave me back some gas mileage but I couldn't tell any torque difference from my stock gears and tires. For me I don't understand why anyone would go to the bother of a gear change and not gain a little torque to help turn those heavy tires.

You'll have a ball with 4.88s and 32s, its not that big of a jump - maybe 600rpm. When I ran 4.10s and 33s I was upset with myself for not going to 4.56s, 4.10s gave me back some gas mileage but I couldn't tell any torque difference from my stock gears and tires. For me I don't understand why anyone would go to the bother of a gear change and not gain a little torque to help turn those heavy tires.

Exactly. I couldn't have said it better my self. Thats the reason I want to chang my gears to give me back the torque. I know they may be a little high for the 32's but for 35's it seems like they would be perfect. It would give you a little more torque to help out with the wieght of tires, bumpers, and etc.

I have a question for yall... I already have 4.10's in the rear and my truck (89 f150) is currently 2wd w/ a 351W and a C6 on 35's. I'm gettin' ready to swap in a solid d44 w/ 37's here in a month or so and was wondering if it would be best to just install some 4.10's in the front while it's out so it will be ready for 4x4, or to wait and re-gear both axles to a lower gear. My truck's mainly an in-town driver, sees freeways from time to time (@ 75mph).

i would wait and install lower gears in both. save up for some traction aids too

You'll have a ball with 4.88s and 32s, its not that big of a jump - maybe 600rpm. When I ran 4.10s and 33s I was upset with myself for not going to 4.56s, 4.10s gave me back some gas mileage but I couldn't tell any torque difference from my stock gears and tires. For me I don't understand why anyone would go to the bother of a gear change and not gain a little torque to help turn those heavy tires.

Exactly. I couldn't have said it better my self. Thats the reason I want to chang my gears to give me back the torque. I know they may be a little high for the 32's but for 35's it seems like they would be perfect. It would give you a little more torque to help out with the wieght of tires, bumpers, and etc.


You guys have caught my eye on 4.88s. My truck is my DD running 35s. I still want to be able to cruise on the highway at 70MPH but I dont want my revs to be super high. Overdrive makes a worlds difference in choosing gears and I like torque :rockon

Bossind, what is your RPMs at 70 MPH with the 35s and 4.88s?
Anybody else who has 4.56s with 35s and the E4OD, what are your RPMs at 70 MPH?

Just trying to get a clue as to what the difference is and how high the rpms would be. I would like to keep it under 2500 at 70 MPH, but I guess thats mainly because I liked cruising in my stock setup at 2000 rpm.

You guys have caught my eye on 4.88s. My truck is my DD running 35s. I still want to be able to cruise on the highway at 70MPH but I dont want my revs to be super high. Overdrive makes a worlds difference in choosing gears and I like torque :rockon

Bossind, what is your RPMs at 70 MPH with the 35s and 4.88s?
Anybody else who has 4.56s with 35s and the E4OD, what are your RPMs at 70 MPH?

Just trying to get a clue as to what the difference is and how high the rpms would be. I would like to keep it under 2500 at 70 MPH, but I guess thats mainly because I liked cruising in my stock setup at 2000 rpm.


You'll have to wait till I finish painting my bronco Stan, but it wasn't even something I noticed on the highway.

stan at 65 with my combo im running 2200rpms. at 70 i think its about 23-2400 at most.

I'll be going with 4.88s when I regear. I'll be stepping up to 37s after I do so.

3.55s E4OD 5.8L and 35s blows. Already smoked one tranny.

I'll be going with 4.88s when I regear. I'll be stepping up to 37s after I do so.

3.55s E4OD 5.8L and 35s blows. Already smoked one tranny.


you will love it brandon I do

stan at 65 with my combo im running 2200rpms. at 70 i think its about 23-2400 at most.

I'll be going with 4.88s when I regear. I'll be stepping up to 37s after I do so.

3.55s E4OD 5.8L and 35s blows. Already smoked one tranny.

you will love it brandon I do

So the new verdict is 4.88 and 35s is a better match than 4.56s? Torque is fantastic especially in the city, offroad, and the rare case of towing, but the cruising is what Im worried about.
Kemical, 2400 at 70 sounds alright to me. Not too high and when I get rid of my droning muffler, it will be more comfortable. I just dont want something that is going to be reving too high and whatnot.

Still looking for someones answer to 4.56s and 35s (E4OD of course).

So the new verdict is 4.88 and 35s is a better match than 4.56s? Torque is fantastic especially in the city, offroad, and the rare case of towing, but the cruising is what Im worried about.
Kemical, 2400 at 70 sounds alright to me. Not too high and when I get rid of my droning muffler, it will be more comfortable. I just dont want something that is going to be reving too high and whatnot.

Still looking for someones answer to 4.56s and 35s (E4OD of course).

Yeah stan it sounds like 4.88's may be the new way to go. It gives you the power and torque you want but still able to run down the highway with it too.

Also for those posting these numbers are your speedo's corrected. I know just with my 32's mine is way off. :doh0715:

Ok my turn and I've read the whole thread. Rewire your bronco? Add MAF, no problem I can do it with my eyes closed. Choose a gear ratio? Someone change my diaper.

My 8.8 grenaded for the 5th time (450,000 miles) so I finally chunked it and put a 10.25 Sterling under it. Disc Brakes, Detroit True Trac, Hy-Tech cover (extra 3 quarts of fluid & cooler). Went to 8 Lug. Did the Chebby swap up front to get matching wheels and tires. I loved the Yokohama's I was running but to get them in 16's I had to switch to metric. I've been running 33's on my stock 3.55 gears since I bought the truck new in '88. Now I've got a strong 393 stroker in it and it USED to be a pretty impressive truck to drive. When I bolted up my 315/75x16 Yokos I feel like I took my stroker out and swapped in a Toyota 22r 4 Cylinder.
I used all the tire calculators and they say my tires are supposed to be 34.2 to 34.4" but when I 1) stood them next to a inflated BFG Mud Terrain 35 then 2) pulled a tape on them they are closer to 36" tall. So, now that I've spent all this money, I have to re-gear.

1st, my Sterling, can I just re-gear it? The Detroit will take whatever up to 5.13's or so right? I can't decide between 4.10s and 4.56s. I have no over drive so I think 4.88 will be over doing it for me.
2nd I have a D44 Open TTB in the front. I also have my D44 SAS tube ready to go under the truck but none of the other more important work has been done (procuring 78 spring mounts, etc.) so no matter what, I have to make a change. My gas mileage has gone from 10 to 5 and the truck won't move. However it will stand up on its nose when I hit the brakes (love the 4 wheel disc with parking brake)

So, some advice please. I'm running a 393 stroker MAF putting out near 400 horses. I was planning on a 502 big block swap towards the end of the summer but this problem has to be solved now. C-6 tranny. No Over drive. Input Please? I'm leaning toward 4.56s which means I just need a carrier for the front, right? I should be good in the back....

Thanks...

What gear ratio is the 10.25?

I wouldn't go over 4:10's unless you (4:10's and 35's will act like 31/32's with 3:55's)
A) Plan to never go on the interstate
B) Go for a larger tire than a 35

If you have overdrive I would go with the 4:56's and 35's.

My gas mileage has gone from 10 to 5 and the truck won't move.

im pretty sure that just because you put larger tires on without resetting your speedo.. if im not mistaken someone correct me if im wrong but yea your gas millage did go down from the larger tires with stock gears but probly not that drastically

also i have an extra carrier for you sitting in a box all ready to go.... you think you could trade for some LEDs.... eh eh

What gear ratio is the 10.25?

I wouldn't go over 4:10's unless you (4:10's and 35's will act like 31/32's with 3:55's)
A) Plan to never go on the interstate
B) Go for a larger tire than a 35

If you have overdrive I would go with the 4:56's and 35's.

No overdrive. The Sterling has a 3.55 in it. (Factory '87 but freshly gone through.)

The Yokos are sitting just below 36" (35 & 7/8")

...and I do spend some time on the interstate... but that stroker I've got in it will turn 6 grand without any issues. Its internally balanced and well built. Hwy cruise of 75-80mph was around 3k on the tach before. Seems like its about 2300 or so now. I'll get a GPS on it tonight as I have no idea how far off my speedo is now (it used to be exactly 7 mph off now I don't know)

So you say stop at 4.10s with my C-6?

One vote for 4.10s

Is there actually a huge difference between 4.10 and 4.56? All the conversion charts I've read look like 2-300 rpm on the hwy... and I'm more leaning toward the grunt. I don't enjoy being passed by Yugos off the light when my engine is worth more than their car..

im pretty sure that just because you put larger tires on without resetting your speedo.. if im not mistaken someone correct me if im wrong but yea your gas millage did go down from the larger tires with stock gears but probly not that drastically

also i have an extra carrier for you sitting in a box all ready to go.... you think you could trade for some LEDs.... eh eh

Its an '88. Mechanical Speedo. My VSS only runs my cruise control and helps the computer a little bit with fuel management...

You have the larger d44 open carrier that will fit 4.10s+?

What do you want for it? You already paid for your LEDs didn't you?

What he is saying about your speedo being off is true. The small gear in the t case that drive the speedo will turn more per one tire revolution making the speedo off. In end of it you mpg may not be as bad as you think. In other words you went from 10 to 5 mpg mat actually be 10 to 7 mpg in reality. 4:10's would help performance greatly.

Here this is a great little tool it will compare the tire size and calculate how off your speedo is.

http://www.miata.net/garage/tirecalc.html

What he is saying about your speedo being off is true. The small gear in the t case that drive the speedo will turn more per one tire revolution making the speedo off. In end of it you mpg may not be as bad as you think. In other words you went from 10 to 5 mpg mat actually be 10 to 7 mpg in reality. 4:10's would help performance greatly.

Here this is a great little tool it will compare the tire size and calculate how off your speedo is.

http://www.miata.net/garage/tirecalc.html

Yeah Yeah, I understand that. I just know how far I drive watch my gas gauge and gauge my mileage that way. I understand that the speedo is further off so my calculation is incorrect if I used the odometer to calculate MPG....

I am definitely re-gearing. I just can't decide between 4:10s and 4:56s.

Thank you for the link!

Sam

Wow. I really need to check it against the GPS. That link says its 25% slow now, when it reads 60 I'm actually traveling 75. I guess that makes sense, as 60 used to be 67 actual and I went up about 3" on tire size....

If it falls "under" your motor does not have to work as hard to turn the tires, but it does it at a higher RPM. This means that as you go more "under" you lose top end. If it's "over" you'll have a higher top end, but less grunt.
************************************************** **********

Thank you.




This is the first time I read this thread...
What is in bold I do not agree with based on my experience.
Gearing it "under" will in every circumstance increase the grunt, speed, power or whatever you want to call it at any and every speed a Bronco or truck can go. Gearing it "over" or higher will actually hurt the top end speed because wind resistance becomes so much more of a factor there. You may find out something like you can do 60mph comfortably in 3rd gear (or you direct 1 to 1), and overdrive works ok at 65 or 70, but to do 75 or 80 you need 3rd gear again because those high gears are not providing the engine a good RPM for making the power needed to push that barn door of a vehicle through the wind.

If you have a stock truck with 3.55 gears and an overdrive transmission I will guarauntee you you will be able to go faster with 4.10's in it. And you will be able to go even faster yet with 4.56 on it.

If you have a stock truck with 3.55 gears and an overdrive transmission I will guarauntee you you will be able to go faster with 4.10's in it. And you will be able to go even faster yet with 4.56 on it.

Yup. That makes sense to me. Thats why I was blabbing about the fact that my stroker turns 6k without slinging rods through oil pans. It will be stronger at all speeds with a taller gear, until you sling a rod. A weaker motor will accelerate and go a faster top speed with a taller gear...


4.56s for me. Decision made.

A weaker motor will accelerate and go a faster top speed with a taller gear...



I don't even agree with that. Unless were getting gears so low that the engine runs out of RPM before it runs out of power against the wind resistance but thats not going to happen unless you're at something like 5.5XX-something with stock tires. On a 300 it would probably happen with a taller gear though.

I don't even agree with that. Unless were getting gears so low that the engine runs out of RPM before it runs out of power against the wind resistance but thats not going to happen unless you're at something like 5.5XX-something with stock tires. On a 300 it would probably happen with a taller gear though.

My point is that through gear reduction you can make a weaker motor seems stronger as it doesn't have to work as hard to make your truck move. I was agreeing with you.... I realize that with wind resistance you are still going to run out of power to physically move the truck be it at 2 grand or 6 grand.

Update
Well I went from 7 mph off to 10-11 mph off. I am getting used to the truck now even with the 3.55s in it. Its not all that bad. I got it up to 110 on GPS and that was about 4500 RPM and it ran out of steam there... I towed one of my boats today. My heavy 20' Searay that weighs more than my Bronco and it did ok. A little of the oomph is gone but it still towed it without a problem and it sure seems to have better towing manners now with 4 wheel disc brakes and that nice monster axle under it so.. Its not as bad as I first thought it was going to be. It also seemed to help when I inflated the tires to their 50 psi rating. (up from 40). I'm going to get my SAS done up front then re-gear. Its not as crushing of an emergency as I first thought it was. Thanks for all the replies! :beer :thumbup

Sam

I'd still go for a 4.56. 4.11 isn't worth the trouble. You can still make a big block turn 6500 also. And I would like to see you do it!!!!!!

I´m re-gearing my Bronco 1981.I have 3.50:1 and I want to go 4.09:1.I know I have to change the carrier.Front an rear D44 carriers are same??:whiteflag:whiteflag
I´m asking cos I live in Argentina and front D44 are almost impossible to find.I could get a rear D44 for 4.09 gears but I don´t know if ii will work in front.

Thanks:beer
Henry

I´m re-gearing my Bronco 1981.I have 3.50:1 and I want to go 4.09:1.I know I have to change the carrier.Front an rear D44 carriers are same??:whiteflag:whiteflag
I´m asking cos I live in Argentina and front D44 are almost impossible to find.I could get a rear D44 for 4.09 gears but I don´t know if ii will work in front.

Thanks:beer
Henry

The rear should be a 9" rear (not a D44) and does not require a new carrier.:thumbup

Sorry, I was talking about the front dif.Here there are a lot of cars and trucks with D44 in the rear.The F150 4x2 in my country is D44 in the rear(not 9").As long as 4x4 vehicles with D44 in front dif. are very rare to find , I wanted to know if I could use a carrier that was originally from an F150 rear dif. with 4.09 gears.(I have the 4.09 reverse to install on it).So the thing is if D44 TTB and the rear D44 from a Ford Truck use the same carrier??
I found out that..YES!!:beer....front and rear D44 use the same carrier....

In my country a TTB front dif D44 complete all stock costs about 1500/2000 :doh0715: .....cos are very rare to find......thats why I was wondering if a rear carrier would work...(costs 200 a complete rear axel:beer)

Here there are a lot of cars and trucks with D44 in the rear.The F150 4x2 in my country is D44 in the rear(not 9")

Ok here they either put the 9" or the 8.8 in the rear of our trucks but it you have a rear D44 I don't see why the carrier would be different. Do you have any pictures of the rear???:toothless

Question:
I would have been fine with my factory carrier in my 10.25 to go up to 4.56s.. but I've got a Detroit True Trac with 3.55 gears. Can I regear it to 4.56s or am I going to have to replace it? I know I said a month ago I thought it was ok, but I want to make sure before I buy my gear kit...

lets see. 4.56, fast off the line, loads of power, no top end. high revs.

3.03 , crap acceleration, no power, lots of top end speed. lower revs.

I pick one below 4.56.

4.30 . I think the 4.30 would be the best of both worlds for you.

on the diesel forums, people like that gear.

on the diesel forums, people like that gear.

That makes absolutely zero sense. Diesel motors have a MUCH lower power band than a gas motor. You're comparing apples to oranges.

That makes absolutely zero sense. Diesel motors have a MUCH lower power band than a gas motor. You're comparing apples to oranges.

You think so?

The diesel guys are making a little more power, than this poster has in his 393, but the weight of the diesel also has an effect on power as well.

If it were a normal 351w or 460, maybe I would go along with you, but since this is a built 393 kicking out 400 hp, and talks of going to a 502 this year, the powerband issue for me is moot.


But you go and run your 4.56 because you think that is the only answer.

Thank you for the reply. I think there would be an issue with 4.30s. I'm pretty sure the reverse cut gear isn't available for something. Either the D44 or my Sterling. I remember hearing something... Also, I think he was saying that Diesels make their torque at a much lower RPM than a gas engine...
But, my truck would turn 33's over off the line with my old 8.8 so I know I've got some decent grunt and I can spin to 6k easily without grenading...

I had actually already decided on 4.56s up a few posts. I like the though as I'm running basically 36" tires and may go taller. I was asking if they would fit on my carrier.... My Detroit Tru Trac that is in my Sterling 10.25. It has 3.55s on it and I didn't know if it would fit 4.56s (the same way you have to change a D44 carrier to go above 4.10s... I know I'm going to have to buy a new open carrier for the front but I am praying I don't have to mess with the Tru Trac. I was just asking if anyone knew the answer...
You are correct about the power I'm pumping out.. and I really am more interested in off the line wheel spin than top speed. I'd be happy now that I've got a rear end that can handle it, to light 'em up every now and then.. maybe catch second.. I'm sure I'll be twisting my driveshaft in half pretty quick, but I'm intending on replacing it with something beefier pretty quickly anyway.


Sam

You will have to get a new carrier for the D44 but save your spiders. As far as I know those are on national back order..unless someone has them that I don't know about. As said in the vendor forum I dont know about the detroit itself but the regular 10.25 has no break.

No problem rescuebronc. I wish you the best of luck with it. I was just looking at the alternative from 4.56 and 4.11.

I want to sas badly, but the money is a deal killer, as is new wheels. If I go gearing, I am wanting 3.73's

Gas expense will play a part in mine. I want to haul things, but can't afford the gas to make any money doing it.

Alright guys I have read through this sticky and now I want some opinions. I have a 92 Bko with a 351 and E4od. I am running 38.5 tires on it as well. My question is this which would you guys think would be a better gear for me 4.88's or 5.13's? You see I know that 4.88's will be an okay gear for my set up but I don't want to put them in and wish I had did 5.13's. I do mostly around town driving and everynow and then I do alittle highway driving. I just dont want to be at 4000 rpms going down the highway at 70. I see alot of people now running 4.88 on a bronco with 35s and they seem to be happy with that choice. So should I step up to a lower gear (5.13) since I have a bigger tire than their 35s? I don't offroad this thing alot so that to is why I am asking because again I don't want to go to low and loose all kinds of mpg and rev too high on the highway.

I recently bought a Dana 70 rear, was re-geared to 4.11. I am wanting to put 4.88's in it will that 4.88 ring gear match up to the 4.11 carrier? From what I found it will, but not 100% sure of it.

In all honestly I'd like to put an ARB in it, and if I go that way I wont have to worry about the carrier size that's in it now.

Eric-Could you shoot me a quote for 4.88's, and if you can Detroit Locker

How far apart numericaly is ok for gears without the risk of failure? If you have a D44/9inch combo regearing the D44 to 4.09 is as close as you can get if you geared the rear to 4.11. is the difference of 0.02 going to make a difference or do they have to be the exact same?

anybody?

Alright guys I have read through this sticky and now I want some opinions. I have a 92 Bko with a 351 and E4od. I am running 38.5 tires on it as well. My question is this which would you guys think would be a better gear for me 4.88's or 5.13's? You see I know that 4.88's will be an okay gear for my set up but I don't want to put them in and wish I had did 5.13's. I do mostly around town driving and everynow and then I do alittle highway driving. I just dont want to be at 4000 rpms going down the highway at 70. I see alot of people now running 4.88 on a bronco with 35s and they seem to be happy with that choice. So should I step up to a lower gear (5.13) since I have a bigger tire than their 35s? I don't offroad this thing alot so that to is why I am asking because again I don't want to go to low and loose all kinds of mpg and rev too high on the highway.

Since you're not going on the highway much, go with 5.13s. The extra gearing will help with around town driving. You wont be near 4000 rpm with either setup.

How far apart numericaly is ok for gears without the risk of failure? If you have a D44/9inch combo regearing the D44 to 4.09 is as close as you can get if you geared the rear to 4.11. is the difference of 0.02 going to make a difference or do they have to be the exact same?

Without ANY risk of failure? Zero difference really. I have seen guys run that combo though. I imagine you'll want to restrict the use of 4x4 to mud and soft sand, where the tires would be allowed to spin at slightly different speeds. 2wd, of course, wont be an issue. Still, Id try to find a way to get around this, even if it meant going a ratio lower.

How far apart numericaly is ok for gears without the risk of failure? If you have a D44/9inch combo regearing the D44 to 4.09 is as close as you can get if you geared the rear to 4.11. is the difference of 0.02 going to make a difference or do they have to be the exact same?

I ran this same set up in my 79 and had no problems. I never ran it at highway speed but it was driven in the snow on the streets all the time.

How far apart numericaly is ok for gears without the risk of failure? If you have a D44/9inch combo regearing the D44 to 4.09 is as close as you can get if you geared the rear to 4.11. is the difference of 0.02 going to make a difference or do they have to be the exact same?

To give you a difinitive answer - 4.09 and 4.11 will be absolutely fine. As long as you're within a couple percent (just from the back of my mind, it's about 3% according to the factory, if I remember right), you'll be good to go. 4.11/4.09 is a 0.5% difference, and was also the gear combination the factory used on the "4.10" or so trucks.

Correct, on my Xterra I was running 4.88's up front and 4.90's in the rear..no problems.

I have the M5OD transmission and 35". I am thinking of changing my gears to 4.88's. It appears that only people with an automatics have used this gear/tire combo. Any feedback from someone with the M5OD? Thanks for the input

Hmmmmmmm........... what a lot to take in!!

Ok, so o've just put 35's on my bronc and she definatly labours like f**k now on the road, whereas before she'd show these damn rice racers a good fight.........for about a nano-second!

My points are thus;

if i re-gear to 4.56, will i get the same gas milage as surely she'll be doing a lower MPH at the same RPM in the same gear, so therefore i would have to have a higher RPM to achieve the same speed in top (which i probably wouldnt be able to achieve!)

Secondly, whats a locker and do i need one?? (i'm from the uk, sorry!!)

Thirdly, where do i get these gears from cos everywhere i'm checking seems to ask for my vehicle year then tell me i can only order stock!!

Forthly, i've searched this site and cant find how to do it, now thats not such a big problem if you live in the US but over here in the UK, not everyone swaps axles on their mini's you know!

Fithly, do i need any extra parts for my axles or wil it all come in a kit and thats that?

And finally, i am planning on boosting my engines BHP (finances permitting!) so what happens to my top speed etc then? is it going to be constrained by the gearing and should i re-gear down again to benefit both acceleration and top speed?


first off our trucks will never be "fast" they are not made to be even quick. they have a shit load of torque and plenty of power bone stock. now when adding lifts, tires, lights, stereo's, winches, and all the other goodies without adding some balls, they are going to be even slower than you can imagine but they weigh close to 6000 lbs. what do you want?

now 4.55's will put you back to about the same rpm as you were stock, but here is the catch. if your speedo is saying 60 mph than you are actually going a bit faster, i dont have the numbers, but if you dont reprogram your speedo it thinks a 29" tire is rotating at X rpm's but in reality you have a 35" tire rotating at that rpm moving you faster than it says. also your odometer is reading stock rpm" thinking you have traveled 1 mile when actually you have gone 1.5 (again i dont have the math in front of me but the theory is correct)

Have you heard or seen a "one tire fire" that is an open rear end which sends power only to one wheel, the one with least resistance. a locker sends power evenly to both wheels all the time. these are not good for street applications and should be kept off-road only they really limit your ability to turn and can be dangerous on-road. there are auto lockers, and air lockers these act like an open rear end until engaged. these are a personal preference and what you are going to do with it.

lastly talking about engine upgrades. GOOD, but it wont do anything for top speed. trust me these trucks are fast enough on the highway. now i dont know how it is in the UK but in the states they are limited to about 90 mph and that is plenty fast. what you will get is a huge improvement on how fast it gets to speed, acceleration/torque that is what true bronco fans are always looking for "TORQUE" top speed will kill you in these things.

oh and summitracing.com has practically everything you could need, gears, heads, supercharger, lockers, exhaust, everything. hope i helped in some way.

Well after lookin at everyones calcs and such, I think I will most likely stick with my stock gears, whatever they are. I would say 3:55s but IDK...I am buying 33x12.5x15s next week, Butmy truck is gutless even with 41k on a rebuild! I do 97% city driving and well less then that for highway. I am thinkin on a 460 swap so gears may wait...we'll see if i cant get some more HP out of my 400

Well after lookin at everyones calcs and such, I think I will most likely stick with my stock gears, whatever they are. I would say 3:55s but IDK...I am buying 33x12.5x15s next week, Butmy truck is gutless even with 41k on a rebuild! I do 97% city driving and well less then that for highway. I am thinkin on a 460 swap so gears may wait...we'll see if i cant get some more HP out of my 400

You likely have 3.55s, but you never know. Mine came with 4.11s, so anythings possible. Its kind of a waste of money to re-gear unless you're going to 4.56s or lower. 4.56s w/ 33s and a C6 would be a little rough on the highway, but since your rig is almost 100% city driven (you're not planning on going much faster than 45), 4.56s would probably net you better mileage and power. Just my .02.

well, I got the 33s and I think i am still getting the same mpg...I'll find out this tank. a mechanic down the road from me helped my change my timming, its at 20 degrees before TDC and I adjusted the carb. I have better throttle response, but still seems to be a dog. So I am debting the 4bbl swap now. And i am pretty sure I have the 3.55s or 3.50 gears

well, I got the 33s and I think i am still getting the same mpg...I'll find out this tank. a mechanic down the road from me helped my change my timming, its at 20 degrees before TDC and I adjusted the carb. I have better throttle response, but still seems to be a dog. So I am debting the 4bbl swap now. And i am pretty sure I have the 3.55s or 3.50 gears

Remember, bigger tires will throw off your speedo/odometer...which will give you false MPG calculations.

Remember, bigger tires will throw off your speedo/odometer...which will give you false MPG calculations.

so you gotta P your PSOM...

So many pages of nonsense. This was supposed to be a sticky. READ HERE and then GO POST ELSEWHERE in the proper area for your vehicle. Posting crap here just clutters this.

4.88,s runnin 37's on a 5.0 w an e40d 90 fsb
just got the gears done professionally and now i have a vibration through the whole truck.. not that it wasnt there before... its just more predominant/ noticable now that the od actually getts used ; )
i was running 3.55s and w 270.xxx miles on her she wasnt goin anywhere fast..
i like the 4.88s but am now running a little high on the rpms at 75 mph then i figured.. about 2200..
any ideas on the vibrations would help.. it has all new bearings up front and new balljoints.. running the chevy 8 lug outters and a 10.25 out back..
had my d.s. shortened and the guy told me balanced it.. hmmm?
u joints seemed fine at the time of the swap..
but the 4.88s are nice.. maybe shoulda gone 4.56..??

4.88,s runnin 37's on a 5.0 w an e40d 90 fsb
just got the gears done professionally and now i have a vibration through the whole truck.. not that it wasnt there before... its just more predominant/ noticable now that the od actually getts used ; )
i was running 3.55s and w 270.xxx miles on her she wasnt goin anywhere fast..
i like the 4.88s but am now running a little high on the rpms at 75 mph then i figured.. about 2200..
any ideas on the vibrations would help.. it has all new bearings up front and new balljoints.. running the chevy 8 lug outters and a 10.25 out back..
had my d.s. shortened and the guy told me balanced it.. hmmm?
u joints seemed fine at the time of the swap..
but the 4.88s are nice.. maybe shoulda gone 4.56..??

Were you running the 37s prior to the gear install? If not, then Id suspect they need to be rebalanced. If not that, then Id suspect the drive shaft wasn't balanced too well. Either way, I don't think a poor gear install would cause the problems you are describing.

Also, 2200 rpm at 75 mph? Are you saying that is high? That's pretty nice if you ask me. Any lower, and Id suspect that 5.0L would have trouble maintaining OD.

4.88,s runnin 37's on a 5.0 w an e40d 90 fsb
just got the gears done professionally and now i have a vibration through the whole truck.. not that it wasnt there before... its just more predominant/ noticable now that the od actually getts used ; )
i was running 3.55s and w 270.xxx miles on her she wasnt goin anywhere fast..
i like the 4.88s but am now running a little high on the rpms at 75 mph then i figured.. about 2200..
any ideas on the vibrations would help.. it has all new bearings up front and new balljoints.. running the chevy 8 lug outters and a 10.25 out back..
had my d.s. shortened and the guy told me balanced it.. hmmm?
u joints seemed fine at the time of the swap..
but the 4.88s are nice.. maybe shoulda gone 4.56..??

Anything thats turning faster as a result of the gears is where you want to look, I suspect driveshaft!

I'd look more closely at driveshaft too.

I think your RPM is perfect. My preference would have been 4.88 (37's as well, 5.8, but at altitude here in Denver), just so happens the rear had 4.56's when I bought and I wasn't going to change it out for that small a difference.

Ok I just read this thread and didnt find my answer. I'm kinda new to this gearing thing. I have a 96 F150 2wd. I am doing a Solid axle swap here soon and I am trying to figure out what gears to get. It has a 4.9 with a 5spd manual trans. I plan on 33's or 35's. It will be a daily driver mainly and used for camping and such. I like the power and gas mileage I currently get. I currently have 2.73 gears in the rear. So from the calculators posted in this thread if I went to a 33" tire from a 29" tire. I would need a new gear ratio between 2.83 to 3.39's. to get back to stock performance. Is this right or should I just go to 4.10's like eveyone else is? Thanks

Are you sure you have 2.73 gears and not 3.73 gears. I didn't know they ran that High of a gear set? I would go to 4.10's besides the lower gearing the more power you will feel

Are you sure you have 2.73 gears and not 3.73 gears. I didn't know they ran that High of a gear set? I would go to 4.10's besides the lower gearing the more power you will feel

According to the diff tag it says 2.73 I could be wrong though. I didnt look at the door tag.

According to the diff tag it says 2.73 I could be wrong though. I didnt look at the door tag.

I would verify what you currently have first. If it turns out you were wrong, and the gearing you currently have is 3.55, then yes, I'd say 4.10 would be the gear for you.

Im pretty sure you have 3.55s. I wouldn't bother regearing for 33s. If you go with 35s, go with 4.56s.

I do have the 2.73 gears in it. I just went and checked. The beging of the tag says 2 73. So from my understanding it has 2.73 gears and an open diff.
Dont forget its a 2wd F150. So what gears should I go with?

sorry been busy workin..
i am suspect of the d.s. also as the tires and rims werent even taken off during installation of the gears and it wasnt doing it w the 3.73s
i will have the d.s. balanced and see how that goes.. its pretty bad at 3000 rpms which it tends to get into when it downshifts from od at 2200 rpms..
thats why i was thinkin the rpms were a bit high at 75//
so is there a way to change my kickdown cable so its not soo touchy trying to cruise at 75?

I have read this sticky...great info, great forum. I have a 1996 Bronco XLT with a 302 / 5-speed manual, with Dana 44 in front and Ford 8.8 in rear, with the factory 3.55's. I am about to order and have professionally installed a set of Yukon 4.56 gears front and rear, based upon what I have read in this thread. I plan on rising 33" tires and occasionally towing a decent boat (about 4,000 lbs). So I am looking for some more grunt and I rarely go over 70 mph (no, not while towing). This is also my dailey driver. I do not expect to use any tire larger than 33's in the future. I am also putting on a 4" suspension lift now.

My question....before I order the 4.56's and have them installed, is there anything I need to consider now, with respect to a future locker installation ? I know just enough to be dangerous, so I am looking for a heads-up here. If money were no object now, I'd have the lockers installed at the same time as the re-gear, but it's not in the budget. At this time, I am not certain of which locker I will use in the future... that's another project.

Any real estate, mechanical or performance issues I should be aware of now before I take the plunge into these 4.56 's ? Comments ?

Thanks in advance.

I have read this sticky...great info, great forum. I have a 1996 Bronco XLT with a 302 / 5-speed manual, with Dana 44 in front and Ford 8.8 in rear, with the factory 3.55's. I am about to order and have professionally installed a set of Yukon 4.56 gears front and rear, based upon what I have read in this thread. I plan on rising 33" tires and occasionally towing a decent boat (about 4,000 lbs). So I am looking for some more grunt and I rarely go over 70 mph (no, not while towing). This is also my dailey driver. I do not expect to use any tire larger than 33's in the future. I am also putting on a 4" suspension lift now.

My question....before I order the 4.56's and have them installed, is there anything I need to consider now, with respect to a future locker installation ? I know just enough to be dangerous, so I am looking for a heads-up here. If money were no object now, I'd have the lockers installed at the same time as the re-gear, but it's not in the budget. At this time, I am not certain of which locker I will use in the future... that's another project.

Any real estate, mechanical or performance issues I should be aware of now before I take the plunge into these 4.56 's ? Comments ?

Thanks in advance.

Here is my .02.

I just got done putting 4.56 gears in my bronco last week and I have 32's (will be changing out to 33's soon.) I love the power and torque range that it's in now. Yes the RPM's are a little high at 70 I am turning right at 2500 rpm. But with a new 302 it seems to really smooth out there and just cruises down the road.

With you having a man trans you could go either way 4.10's or 4.56 and have good amounts of power with 33's. Simply becuase your final drive ratio is a bit better then the AOD. Also you will also find that most gear companies want you to get a "notched" cross pin. Do some searching around here on that subject. My Yukons said to do that but I opted not to. Also dont forget to order a new front carrier with those gears. Your stock carrier wont work.

As far as your lockers go. If you go with a locker that you will have to replace the carrier then you will just be setting up the gears twice. I dont like doing things twice. Thats why I went ahead and put 4.56's in mine. I knew one day I would be going to 35's.

Hope that helps :whiteflag

Found a new calculator I like... http://www.et-studios.com/motorsports/gears/gears.html

It does not account for auto slippage add another 10-15% for that.

so if what i read is right 4:10 would give me more top end but less low end punch
and 4:56 would give me more grunt but less top end
so then my next question would be that since these are for E40D's how similar is an AOD to the E40D

so if what i read is right 4:10 would give me more top end but less low end punch
and 4:56 would give me more grunt but less top end
so then my next question would be that since these are for E40D's how similar is an AOD to the E40D

Ill assume this is for your rig with 35s...
Your NOT getting more power up top with 4.10s. I think what you're referring to is wheel spin. A higher gear ratio will allow you to spin the tire faster than a lower one without shifting. It also takes more power to get the tires spinning with a higher gear....most commonly guys running big blocks or diesels will do this, like running 4.11s with 40''+ tires, which would normally require 4.88s or 5.13s.

In your case, just go with the 4.56s, or even 4.88s. You're already at 3.55, and going up to 4.10s (only 0.45 lower) is kind of a waste of both time and money.

thanks for that man

One more: Gear Ratio Calculator at grimmjeeper.com (http://www.grimmjeeper.com/gears.html)
This one already has ratios for many trannies & t-cases. You choose components from a drop down or you can enter your own ratios. The results are shown side by side so you can compare different combinations.

thanks for that man

werd :thumbup

thanks to http://nationaldrivetrain.com/

http://i537.photobucket.com/albums/ff336/clemmer3000/GearApplicationChart.gifpink good area to be in

WHAT IS MISLEADING ABOUT THIS CHAT IS IT IS BASED OFF OF 55 MPH AND NOT 65 MPH LIKE MOST OF THESE CHATS!!!!


The chart shown below shows RPM calculations at 55 MPH for various combinations of final Gear Ratio
and Tire Diameter.



thanks to http://nationaldrivetrain.com/

http://i537.photobucket.com/albums/ff336/clemmer3000/GearApplicationChart.gifpink good area to be in

Notice about a 500 RPM difference...;)



Note: This chart is based on engine rpm at 65 mph with the transmission in a 1:1 gear ratio (Third with a three-speed manual, Fourth with a four-speed manual, or Third with an Automatic). Remember, the actual rpm indicated in the chart will be slightly higher (between 100 and 300 rpm) on vehicles equipped with an automatic transmission. This is due to the slip present in an auto transmission's torque converter.

http://www.4wheelonline.com/images/gear-chart.gif

Dale has Allan seen that second chart (in the above post). Those are pretty close to the numbers I run when I am not in OD.

Dale has Allan seen that second chart (in the above post). Those are pretty close to the numbers I run when I am not in OD.

Yeah we had looked at it before..;)

Question about upgraded LSD carriers able to take bigger gears:

I searched hard, but I can't find a definitive answer on my particular setup. Your quick help on this would be greatly appreciated:

10 years ago I replaced both front and rear OEM open diffs (D44/8.8") with "complete factory Ford Posi Traction carrier assemblies" (that's what the transmission shop wrote on the receipt) re-using my original stock 3.55 gears. I'm assuming they actually were referring to Trac-loc units.

Now I'm getting ready to change out to 4.88's, and I'm not sure which carriers I have to change to take the new gears? And exactly what has to be changed - just the carrier case or the entire assembly (internals etc.)?

Thanks!

S.

Question about upgraded LSD carriers able to take bigger gears:

I searched hard, but I can't find a definitive answer on my particular setup. Your quick help on this would be greatly appreciated:

10 years ago I replaced both front and rear OEM open diffs (D44/8.8") with "complete factory Ford Posi Traction carrier assemblies" (that's what the transmission shop wrote on the receipt) re-using my original stock 3.55 gears. I'm assuming they actually were referring to Trac-loc units.

Now I'm getting ready to change out to 4.88's, and I'm not sure which carriers I have to change to take the new gears? And exactly what has to be changed - just the carrier case or the entire assembly (internals etc.)?

Thanks!

S.

you will have to change the carrier in the front only to a 3:73 and numericly higher set up ,it should not be very expensive ,i beileve that the going rate on a posi for the d44 is around 220 or so

Ok, so things have changed a bit... About 6-7 years ago I regeared to 4.10's w/ my 35's (351W & C6). Now I'm running 37's and it seems a little sluggish, but maybe that's just me. What ratio do you guys think would be prime for mainly in-town driving (25-45) with the rare occasion of freeway driving? I want to keep it in the RPM range that suites it best if possible. Thanks guys...

If you are still running the C6 I would run a 4.56 but thats it. I wish there was a gear inbetween the 4.10's and 4.56 it would make that a little easier for you.

True, 4.56s should get you back to where you were with the 35s, but for in town driving, the lower you go the better...less wear and tear on your drivetrain, probably better mileage too. Id say 4.88s should work well. Youll get better performance and probably wont even notice any rpm increase until you get about 50 mph. Hell, if you had OD and 1-tons, Id say 5.13s...

I wouldn't go more than a 4.56 with 35's personally. Quick question, do you still have the 8.8 in there or did you swap out to a 9"...if you do have a 9" Randy's offers a 4.30 gearing for the application.

I'm currently running a D44 (3.55's) up front and the 8.8 (4.10's) in the rear w/ 37's. Yeah I'm plannin' on stayin with the C6. I just swapped out my 2wd C6 for a rebuilt 4x4 C6/NP208.

Ok well ive got a question for everybody. If i were to swap my gears from 3.55s to 4.10s would my stock limited slip still be able to be used with the new 4.10s and the other thing is would i have to recalabrate my transmission and how hard would that be todo my self or how much do yall reckon it would cost to get done somewhere?

Ok well ive got a question for everybody. If i were to swap my gears from 3.55s to 4.10s would my stock limited slip still be able to be used with the new 4.10s ?

Depends on which axle you are referring to. The Front you have to get a new carrier. The rear carrier will work.

the other thing is would i have to recalabrate my transmission and how hard would that be todo my self or how much do yall reckon it would cost to get done somewhere?

Why would you need to recalabrate the trans? If your wondering about the speedo that is done with a gear in the TCase. I am assuming you have a 84 BTW. As far as doing the job yourself if you have never done it and never been in an axle before I wouldn't even try to do it. There are special tools required to get it done right.

Do a little reading on here and you will find all the info you want on gears. :thumbup

Thanks for the info and yea my bronco is a 1984 4x4 with the 302, 8.8 rearend, and a c-6 transmission. And yea ive been all through my rearend and totally disassembeled it before because there was a shimy in it but i got that gone fast. Now what all would i have to do to the limited slip in the rear to make it adaptable to the new 4.10 gears? Aint there a spacer that i would have to put in or something of that nature? Thanks for the info

Thanks for the info and yea my bronco is a 1984 4x4 with the 302, 8.8 rearend, and a c-6 transmission. And yea ive been all through my rearend and totally disassembeled it before because there was a shimy in it but i got that gone fast. Now what all would i have to do to the limited slip in the rear to make it adaptable to the new 4.10 gears? Aint there a spacer that i would have to put in or something of that nature? Thanks for the info

Sorry I changed my post above to be a little more clear. The rear carrier L/S is fine you don't have to do anything to it when doing a gear change. It's the front you have to change.