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Discussion Starter #1
Hey Guys,

Have a few questions about a gear swap on my 95 Bronco XLT, 302, E4OD, 31" off brand AT's (152K miles on the truck). It has the stock gears in it now, but it feels like the rear is about to take a dump on me and I'm stuck in a dilemma.

In the next six or so months I'm going to put a set of 33" BFG AT's or MT's and later "maybe" some 35's same brand and/or style. I'm going to be using the truck for occasional weekend wheeling and hunting (Mud and Gravel roads mostly, NO rock crawling), pulling a boat, pulling a bike trailer (1 4wheeler and 2 bikes at most), pulling a small camper and driving back and forth to work once or twice a week (60 miles round trip ON THE HWY 70mph+).

I've had a local drive line shop give me a quote on a 4.10 setup, front and rear, for $1400-$1700 parts and labors w/ warranty (Parts include new ring and pinion, bearings, seals and a new carrier for the front end). They also gave me a quote of $850 to put a new set of 3.55's in the rear (includes all parts and labor). The shop was recommended to me by three Ford service depts, one machine shop and light duty mechanic shop (Bottom line, good rep in the area).

Given what I'm going to be doing with truck, is it worth the extra $850 to swap in a set of 4.10's? If not, what would you recommend from experience? Other gear ratio swaps would probably run about the same price at this shop.

Not too concerned with gas mileage, I drive a 25 mpg car to work most days. However I will be taking trips out-of-state with the truck on occasion (300+ miles) and would like to keep the MPG above 10-12, if possible. Overall Durability of drive line components is a bigger concern. I don't want to work the transmission or engine to death needlessly trying to run too high of a gear.

Thanks,
CE
 

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FSB's Dirty Jersian
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Hey Guys,

Have a few questions about a gear swap on my 95 Bronco XLT, 302, E4OD, 31" off brand AT's (152K miles on the truck). It has the stock gears in it now, but it feels like the rear is about to take a dump on me and I'm stuck in a dilemma.

In the next six or so months I'm going to put a set of 33" BFG AT's or MT's and later "maybe" some 35's same brand and/or style. I'm going to be using the truck for occasional weekend wheeling and hunting (Mud and Gravel roads mostly, NO rock crawling), pulling a boat, pulling a bike trailer (1 4wheeler and 2 bikes at most), pulling a small camper and driving back and forth to work once or twice a week (60 miles round trip ON THE HWY 70mph+).

I've had a local drive line shop give me a quote on a 4.10 setup, front and rear, for $1400-$1700 parts and labors w/ warranty (Parts include new ring and pinion, bearings, seals and a new carrier for the front end). They also gave me a quote of $850 to put a new set of 3.55's in the rear (includes all parts and labor). The shop was recommended to me by three Ford service depts, one machine shop and light duty mechanic shop (Bottom line, good rep in the area).

Given what I'm going to be doing with truck, is it worth the extra $850 to swap in a set of 4.10's? If not, what would you recommend from experience? Other gear ratio swaps would probably run about the same price at this shop.

Not too concerned with gas mileage, I drive a 25 mpg car to work most days. However I will be taking trips out-of-state with the truck on occasion (300+ miles) and would like to keep the MPG above 10-12, if possible. Overall Durability of drive line components is a bigger concern. I don't want to work the transmission or engine to death needlessly trying to run too high of a gear.

Thanks,
CE
if you are 100% definitely going with bigger tires, yes I'd recommend 4.10's for sure. I had 35's w/ 3.55's and it sucked. Hard.

If you are staying with 31s, before you just swap out to 3.55's I would make sure that is what the problem you are having actually is. And the price rang of 14-1700 is about on par with what I hear from everyone.

check what the labor/parts costs are, you can maybe pick up a gear set cheaper too. Shops are known to charge a lot for parts also.
 

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Discussion Starter #3
if you are 100% definitely going with bigger tires
I'll definitely be going up to at least a 33.

before you just swap out to 3.55's I would make sure that is what the problem you are having actually is
I was going to pull the diff cover this weekend and see what the fluid looks like and see if any chunks fall out. Right now it has a bunch of play in the rear end and it clunks when I stop at a light and clunks when I take off.
 

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http://www.fullsizebronco.com/forum/showthread.php?t=355

I highly recommend moving forward with the 4.10's, especially if you plan to go up to 33's or above. I'm currently running stock gear ratio's with 33's and am tackling that very issue in 2 weeks with my locker install.

"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."
"35" tire, 4.10 gears = forward 26.8", 5% over stock roughly."
 

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Discussion Starter #5
I read this thread a week or two ago, when I joined, and this is what I was basing my ratio selection (4.10) off of. The main thing I wanted to do was confirm I selected appropriate ratio for my application, based on others experiences. Plus there was a little debate in some other threads I read on the subject, about owners not seeing much of a difference when swapping from 3.55 to 4.10. Didn't want to spend a bunch of money and discover I went too low or too high on the gear. I don't want to have to do this again for a while.

Peace of mind thing, yeah know.
 

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I read this thread a week or two ago, when I joined, and this is what I was basing my ratio selection (4.10) off of. The main thing I wanted to do was confirm I selected appropriate ratio for my application, based on others experiences. Plus there was a little debate in some other threads I read on the subject, about owners not seeing much of a difference when swapping from 3.55 to 4.10. Didn't want to spend a bunch of money and discover I went too low or too high on the gear. I don't want to have to do this again for a while.

Peace of mind thing, yeah know.
I'm not much of a gear head myself...so I know what you're saying. The shop I'm working with recommended the 4.10 gearing for my 33's. He said something about liking the teeth on the 4.10 over those on the 4.56, though I didn't really grasp why. I'm going with a 4" BDS lift (with extended radius arm and glide-ride leafs) next month to give my tires a little more room for wheel travel, but not going to move to 35 tires. I don't want any rubbing issues. But if you're positive of using 33's or 35's, perhaps you should be choosing between 4.10 and 4.56 gearing as oppose to 4.10 and stock. Just a thought..
 

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The easiest way to figure out what gearing you should upgrade to for a stockish rpm and power is every inch in tire you go up and .10 to your current gearring.

Example stock tire 29in with 3.55 gears. Now going to 33in tire is 4in taller so add .40 to 3.55 you get 3.95. So the gearing you would want would be 3.93ish.
So for a 35 tire you would want 4.10.

29in tire 3.55 gear
33in tire 3.93 gear
35in tire 4.10 gear

Again this is just a quick guide. If you want more grunt keep going lower in gears.
 

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The easiest way to figure out what gearing you should upgrade to for a stockish rpm and power is every inch in tire you go up and .10 to your current gearring.

Example stock tire 29in with 3.55 gears. Now going to 33in tire is 4in taller so add .40 to 3.55 you get 3.95. So the gearing you would want would be 3.93ish.
So for a 35 tire you would want 4.10.

29in tire 3.55 gear
33in tire 3.93 gear
35in tire 4.10 gear

Again this is just a quick guide. If you want more grunt keep going lower in gears.
You'll find most members here (especially with 302's) will opt for 4.30's or 4.56's and 35's. If you go with 35's and 4.10's you'll wish you would have chosen a lower gear. Most choose 4.10's and 33's and 4.56's for 35's. You'll generally never say, "man, I have too much power off the line"
 

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I think that another thing that is important to consider is the lay of the land and the types of roads you will be regulary travelling in the area that you live when making gearing choices.

For instance the area I live in nothing is really flat and you are constantly climbing or decending grades of some type. Also the closest interstate is over 60 miles away so speed limits above 60 mph are very limited.

With those types of driving conditions then I would consider 4.10's with 33's and 4.56's or maybe even 4.88's with 35's basically a must have with a 302 and a very desirable choice with the 351.

Now if I lived in an area say the midwest or parts of the south where everything was basically flat and there were a lot of roads I travelled that the speed limits were commonly 70+ then perhaps going a bit higher on the ratio would make the vehicle a bit of a better daily road use type of driver.

Anytime you make any modifications to a vehicle whether it be lifts, gears, driveline there will be plus or minuses to the changes and how you plan on using the vehicle and where you plan on using the vehicle really dictate what will work best for your application.

What works best for one will not always be what works best for you. Like for myself the area I live with lower speed limits, lots of hills and no interstates lower gears are the best choice no question. But the guy that lives in a flat area with few if any hills with many roads that running 70+ mph is the norm then the lower gears may limit how well his vehicle performs in those applications.

So when making your choices remember to take all things into consideration to get what works for you.
 

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Your truck has OD, so you can run a steeper gear, and still cruise well on the highway. My Bronco, with C6 tranny, 35" tires and 4.56 gears turns about 2800 rpm, at 70 mph. According to my LEO buddy, my speedo is right on, with this combo, so that tells me I am running close to the same rpms, as stock gearing and tire size. I think that with 4.10 gears and 35" tires, your tranny is going to be doing a lot of shifting OUT of OD gear.
 

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You'll find most members here (especially with 302's) will opt for 4.30's or 4.56's and 35's. If you go with 35's and 4.10's you'll wish you would have chosen a lower gear. Most choose 4.10's and 33's and 4.56's for 35's. You'll generally never say, "man, I have too much power off the line"

Wow, those are some low gears.
 

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I run 4.88's with 35's and a strong 5.8 and I think its the cat's ass. You have overdrive, take advantage of it and run some deeper gears. Unless you like to run 75+ on the highway I'd gear it at 4.56 rather than 4.10.
 

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FSB's Dirty Jersian
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You'll find most members here (especially with 302's) will opt for 4.30's or 4.56's and 35's. If you go with 35's and 4.10's you'll wish you would have chosen a lower gear. Most choose 4.10's and 33's and 4.56's for 35's. You'll generally never say, "man, I have too much power off the line"
No, but you'll say "Damn I just floored this truck for the past 2 miles of the highway, and I still haven't reached past 72mph. What a slow god damn truck now"

I think that another thing that is important to consider is the lay of the land and the types of roads you will be regulary travelling in the area that you live when making gearing choices.

For instance the area I live in nothing is really flat and you are constantly climbing or decending grades of some type. Also the closest interstate is over 60 miles away so speed limits above 60 mph are very limited.

With those types of driving conditions then I would consider 4.10's with 33's and 4.56's or maybe even 4.88's with 35's basically a must have with a 302 and a very desirable choice with the 351.

Now if I lived in an area say the midwest or parts of the south where everything was basically flat and there were a lot of roads I travelled that the speed limits were commonly 70+ then perhaps going a bit higher on the ratio would make the vehicle a bit of a better daily road use type of driver.

Anytime you make any modifications to a vehicle whether it be lifts, gears, driveline there will be plus or minuses to the changes and how you plan on using the vehicle and where you plan on using the vehicle really dictate what will work best for your application.

What works best for one will not always be what works best for you. Like for myself the area I live with lower speed limits, lots of hills and no interstates lower gears are the best choice no question. But the guy that lives in a flat area with few if any hills with many roads that running 70+ mph is the norm then the lower gears may limit how well his vehicle performs in those applications.

So when making your choices remember to take all things into consideration to get what works for you.
I think a lot of the information in here is a good. 4.10s are perfectly fine for a street driven truck. You'll have more than enough gear to make it through shit offroad, and you also have 4x4-Low.

I run 4.88's with 35's and a strong 5.8 and I think its the cat's ass. You have overdrive, take advantage of it and run some deeper gears. Unless you like to run 75+ on the highway I'd gear it at 4.56 rather than 4.10.
Now while I don't really disagree, because he does have O/D and deep gearing works wonders offroad, I do somewhat contest this because 4.10s on 35's or 4.56's on 37s works almost as well, and it'll allow him to save a bit on gas when running freeway speeds.

IMO unless the truck is wheeled twice a week or at least once every weekend, or it is designated to be offroaded and not much else, then yes deeper gearing is great. If you are driving this truck all over bumblefck and then just take it out once every few weekends, I'd take the gas mileage over the tiny bit of extra gearing.

I run 4.10s on 40's (I also have a built 400 though...) but I tear chit up on road, offroad, and everywhere in between. It's nice because I have enough power to run through the mudholes with the best of em', and still get decent mileage.
 

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Discussion Starter #14
No, but you'll say "Damn I just floored this truck for the past 2 miles of the highway, and I still haven't reached past 72mph. What a slow god damn truck now"
Smok3y, this is exactly what I'm trying to avoid. This truck will primarily be a a street driven truck with the option of tacking it out on the farm, hunting lease or camping. So I'm looking at 95% on-road and 5% off-road use and in that 5% I'm not looking at extremely aggressive conditions.

Thanks to all for the guidance on this subject. After taking all opinions into consideration along with where I live and the type of driving this thing will see most of the time. I'm going to go with the 4.10 setup and 33's. The 35's would be less practical and more cosmetic. Now the fun part begins, coming up with the $$ to get it done.
 
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