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Discussion Starter · #1 ·
i just put a 4.5 lift on my truck with 35's
i want to change the gear to make up for the power lose when towing. i can go with 4.10 or 4.56. has anyone done this to thier truck and what gears did you use?
 

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Here's my .02 I put 37's on mine with 3.73 gears and can still tear a house down with the power. I regularly pull dump trailers, enclosed trailers , and tractors. Up to you but I'd just look at a programmer for a little extra oomph and keep the gears for mileage. That's what I'm doing.
 

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Here's my .02 I put 37's on mine with 3.73 gears and can still tear a house down with the power. I regularly pull dump trailers, enclosed trailers , and tractors. Up to you but I'd just look at a programmer for a little extra oomph and keep the gears for mileage. That's what I'm doing.


Ditto........ Same here. With my 35's, I've still got MORE than enough power to do what I need to. My GN trailer empty weighs 7000#. Loaded anywhere from 10,000 to 20,000#.

Psst.....fill out your sig.
 

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plus, i believe a good programmer will fix the tire diameter and, therefore, your shifting (if you have an auto) which I think is kinda the bigger problem.
 

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i got 33s with 3.55 gears no problems here
 

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i just put a 4.5 lift on my truck with 35's
i want to change the gear to make up for the power lose when towing. i can go with 4.10 or 4.56. has anyone done this to thier truck and what gears did you use?
You have not given enough info to make an educated decision,the year,type trans,towing weight predicted use etc.

Bob
 

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Discussion Starter · #7 ·
i have a 6.7 3500 with a bully dog pmt. i towed my 11000lb fifth wheel stock and now with the 35's and its a night and day differance. the truck will still pull it but not like before. i called the gear company today and talked to them and came up with 4.56 to get me back to stock. it will raise rpm's about 70 more then stock but 4.11 will still be lower so i went with 4.56
 

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Discussion Starter · #9 ·
i really didnt want to go threw all the work of changing gears and still have the rpm's lower than stock. every gear company that i have talked to said the same thing go with the 4.56. its ony going to be 70rpms over stock. i just want to get that bottom end back i had when its was stock.
 

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i really didnt want to go threw all the work of changing gears and still have the rpm's lower than stock. every gear company that i have talked to said the same thing go with the 4.56. its ony going to be 70rpms over stock. i just want to get that bottom end back i had when its was stock.
i have 4.10's w/ 35's. and its almost too much. but i love them. cuz it does pull trailers alot easier. i don't recommend 4.56's because that would be just way too much JMO. i remember reading an article of a guy who was doing 12's on 1/4mile on 4.56's but he was rock'n some 40's. ofcourse his rig was like totally built up for it.

4.10's w/35's pretty much puts you to stock(3.7?'s). not exactly 3.73's but pretty dam close. and the guy is recommending the 4.56's because that''s what they do all day to gas vehicles, and diesel s have way more torque than gas. good luck, but i recommend 4.10's. i still get up to 20mpgs empty on highway at 65mph's and about 12mpgs with a 13000lbs trailer going 55-60mph
 

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Discussion Starter · #11 ·
i see you have a 5.9 i have 6.7 with a six speed. the gear ratio is way different. the 68re is 1:1 in forth gear and .81 for fifth and .62 in sixth. all tire to gear charts are for 1:1 at 65mph. my tire size with 4.56 is 2852rpm's @1:1
then take 2852 x .81= 2310 in fifth
2310 x .62=1432rpm's in sixth at 65mph

stock is [email protected] 1:1 @65mph
2715 x .81= 2199rpm fifth gear
2199 x .62= 1363rpm in fifth @65mph

69rpm diff
 

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i see you have a 5.9 i have 6.7 with a six speed. the gear ratio is way different. the 68re is 1:1 in forth gear and .81 for fifth and .62 in sixth. all tire to gear charts are for 1:1 at 65mph. my tire size with 4.56 is 2852rpm's @1:1
then take 2852 x .81= 2310 in fifth
2310 x .62=1432rpm's in sixth at 65mph

stock is [email protected] 1:1 @65mph
2715 x .81= 2199rpm fifth gear
2199 x .62= 1363rpm in fifth @65mph

69rpm diff

Cant argue with that there,you definately have me there on paper. but in real life situation and MY setup, i am at 2755rpm at 66mph........
 

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Isn't stock tire size 265/70-17? That's roughly 31.6" diameter. If stock gearing is 3.73, you need 4.10 to get you close to stock. Here's the formula:

3.73/31.6 = x/35 where x = new gear ratio.
 

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Ive been to well over 10 shops around my area and everyone one has said it would be fuel economy murder to go past 4.10 with anything less than 37"s
 

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I've done gears a few times in my other rigs and thought I would need to change the 3.55's when I bought this truck. I was wrong. I am going 37's on the next tire change, and I have little doubt that the 3.55's will be just fine. If you just have to fool with it, I would find someone who already has 4.10's and trade axles.

There are a lot more folks who want 3.55's and have 4.10's than there are that want 4.10's and have 3.55's. The only issue with the big tires is lack of steering force, and axlewrap going in reverse if your kit does blocks in the rear. My AGR barely turns these tires in parking lots.
 

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Discussion Starter · #19 ·
Isn't stock tire size 265/70-17? That's roughly 31.6" diameter. If stock gearing is 3.73, you need 4.10 to get you close to stock. Here's the formula:

3.73/31.6 = x/35 where x = new gear ratio.
i checked my stock tires and where right at 30''
you can also take your new tire size divide by your old tire size and then x's that by your old gear ratio.

34.5 divide by 30= 1.15 x 3.73= 4.29 gear ratio to get back to stock. they dont make a 4.29 so its 4.11 or 4.56
 

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I have a 5.9 with 35's and 3.73 gears, with the superchip and the power is is still huge, plus I'm at about 1550 rpm at 65 and get 23 - 24 mpg.
 
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