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Discussion Starter · #1 ·
For all you guys out there running 33" tires, did you rear gear? If you did, what gears, 4:10's or 4:56's? ( I have a 95 w/ OD & a 351) Did it make a big difference? Im currently running 32's and would like to go to 33's in the next month or so. If I dont rear gear what could I damage? I did a search & cound'nt find the exact answers I was looking for. Thanks in advance.
 

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Dead Horse
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im running 31's but i do know a few things
you wont really tear anything up with 33's and stock gears, it just will be slow
unless you re gear. alot of people here are running stock gears with 33's, but id like to know also what other gearing people are running witht hese tires
 

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Stock with 33's... seems to be just fine for me. 1600 RPM in OD (with an AOD and 302) at about 60.
 

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Rest in Peace Friend...
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I run both 31's and 33's. As you can see I have 3.08 gears which ar just fine for 31's but with the 33's it starts to lack on the power end. So if I were to regear my truck I'd go for 4.10, 4.56, or even 4.88 depending on where in the power band I wanted my truck to run. There are calculators and charts to aid in deciding where to gear. Bronco engines are designed to run best between 2300 and 2600 at cruise speed. So the gear selection would be different for cruising at 55 than at 65. If you are going to be running mainly off road then a different set of criteria comes into the decision.

Attached is a chart from Jeff's Bronco Graveyard catalog fo 80 and up trucks. Note the chart is set up for a cruise speed of 55 65 will shift the numbers about 4 columns to the left.
 

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I'm going with 4.56's when I buy my 33's just because my truck is a slug and I want some nice low end power. 4.10's will work better with your truck most likely because of the 351 over my 302.

If youve got a weak motor, I'de go with the 4.56's. if you have a strong motor and dont plan on going any higher than 33" tires, I would go with 4.10's just because of gas mileage.
 

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Discussion Starter · #6 ·
Is there an easy way to find out what gears I have. My truck has the factory towing package. Could it of come with 4:10's ?
 

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ffmike said:
Is there an easy way to find out what gears I have. My truck has the factory towing package. Could it of come with 4:10's ?
look at the door jam and see what axle code you have..

axle code H5 is 4.10 LS rear for a 8.8, my old '89 had factory 4.10's and my new '89 has 3.08's..i need to regear..
 

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green ones make me horny
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I run 33s on mine with stock gears and it is good to go with mine
 

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Engineer
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jb77714 said:
im running 31's but i do know a few things
you wont really tear anything up with 33's and stock gears, it just will be slow
unless you re gear. alot of people here are running stock gears with 33's, but id like to know also what other gearing people are running witht hese tires
Don't talk unless you have experience. 3.55's will lite up 33's no problem and it runs 2000 rpms on the highway at 70mph. 33's are fine stock
 

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Excessively Engineered
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I always hated those gear charts. Not worth a crap imo. If your stock gears are 3.55 or 4.10 then you will be fine. My freaking bronco came with 3.07 gears. I couldn't spin 32" tires over on loose gravel. Sucked bad.
 

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Harmful if swallowed
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I have run 33's and 3.55's for a while. It's enough power, but I like more.

I am still planning 4.10's when I get the money and swapping back to 32's, but possibly moving up to 17's as well.

I really wished they made 4.30's in reverse cut for the D44 :cry
 

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NOTE: The posted gear/tire chart is for a 1:1 final gear transmission, i.e. no Overdrive. With OD you're looking at a little lower RPMs.

I'm currently running 32s and 4.10s with a 5spd (OD) transmission and run about 2500rpms at 60mph. A little high for my taste and out of my motors power range so my mileage is horrible (est. 10mpg).....BUT all the low end grunt I could ever ask for and it is niiiiiiiiiice. :D :D :D
 

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Just got 4.10 gears installed on my 96' with a 33s & a 351W. My stock 3.55 gears were fine on flat land however on long hills I always had to switch off the O/D to keep at 55 mph (with the rpms up). On a steep hill I was doing 45mph tops and stepping on it. With the new gears I didn't notice a huge difference around town but the hills are now no problem. I am just breaking in the gears so no wheeling yet but I can idle up driveways.
I do wonder if I could have lived with 4.56s. :shrug
I don't plan on going much bigger than 33s so it might be right on.
 
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FSB warrior
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Running 4.56 or 4.88 with 33's is crazy. How fast do you want to be able to go on the highway 45??? 50 tops. 4.56 work good for a trail driven 35, or street/trail driven 37, 4.88's are for 38-39 inch tire
I know a guy who has 4.88's and 35's and he can only drive 50 on the highway.

If you upgrade to 4.10, you can go to 35's and still have low end.
 

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I just started running 35" with stock 3.55 gears and a stock 351 W/ E4OD. Its not that bad. I towed with it last weekend and it was not bad at all. In the long long run I may look to add some power or maybe re gear.
 

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I did 4.56's because I will be going to 35's soon. It's not that bad IMO, 2k RPM's in OD on the freeway is about 60MPH. If you don't plan on anything bigger than 33's I would either do 4.10's or deal with the 3.55's.

33's and 3.55 was a little slugish. I found myself running with the OD off except on the freeway. It wasn't to good towing my boat either, even with the OD off most of the hills I was loosing speed. :banghead

The difference between 3.55's and 4.56's was awesome. It feels like a whole new truck. I like it. :rockon
 

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Discussion Starter · #17 ·
I just had a chance to check my axle code. It is 19. From the research I did axle code 19 translates to 3:55 gears. Anybody know if this is correct.
 

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ffmike said:
I just had a chance to check my axle code. It is 19. From the research I did axle code 19 translates to 3:55 gears. Anybody know if this is correct.
it is correct and you have an open diff
 

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Rest in Peace Friend...
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lightnin said:
I always hated those gear charts. Not worth a crap imo. If your stock gears are 3.55 or 4.10 then you will be fine.
:shrug

The problem is that a lot of people don't know how to properly interpret them. That one is right on for Ford trucks with stock 300, 302 and 351W engines. It is within 100 RPM of what I get with my truck and what you just said about 3.55 and 4.10 is the same thing that is indicated by the chart.

That chart, for example, is calibrated based on 55 MPH highway cruise with no OD. If you cruise at 65 the numbers shift about 5 columns to the left. The charts are only for quick reference and use the listed tire size. That chart is within 50 RPM.

If you use the formula above the chart the result will be dead on with what you will actually see when cruising without OD, that is if you use the actual diameter of the wheel rather than what is listed as. ex. 33's are not necessarily 33 and will vary depending on the rim with. ex. 33 x 12.5's on a 10" wide rim has a overall diameter of 32.3 inces. So the charts claim of a cruse RPM of around 2K is accurate.

:thumbup
 

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Hmm. With that being said. It don't make any difference with a granny low 4 speed or a c6 automatic. I know a granny low will turn bigger tires alot easier than a c6 will. I just don't like the chart.
 
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