Regearing a 1500HD

Adrian17 · August 28, 2018

So i got way bigger tires than what my truck had went from a 245/75/16 to a 275/65/20 which is a 34x10r20 if i remember correctly. Well needless to say the truck lost a good amount of power (knew this before vuying tires). Whats a good gear to jump to? I have 3.73 right now would 4.10 be a good choice? Also im planning to go to a smaller tire because these rub a bit and its really annoying. Going to a 285/55/20 or 275/60/20. Also I do pull a two horse trailers with of course two horses and a flat trailer sometimes.

Adrian17 · August 29, 2018

Anybody? Even if it is a 2500hd what did you guys move to?

SierraHD17 · August 30, 2018

4.56 with the 4L80E. I have 4.10's in my both my 04 and 05 1500HD's and its "okay" with stock tires. For reference I have a 2017 2500HD 6 liter and run a 295/60/20 which is real world about 33.5" tall. I have 4.56 gears in that truck and it's the best thing I have done to the truck. And remember that your 80e's first gear ratio in the transmission ( 2.48:1) is more or less my 2017's 2nd gear in the 6L90E ( 2.36:1)..... first gear in my 17's trans is 4.02:1!

Gears are your friend... and before you say anything about highway rpm you will turn the exact same rpm I do with 4.10's and 245/75/16's......

Adrian17 · August 30, 2018

Yea I did some reading on the RPMs on highway not to worried about it. You say you have 4.10s in your 1500HDs and if feels just ok on stocks? Also like I said im moving down a tire size or two. Ill look into the 4.56s. Also do you remember how much you payed for the regear on the 1500HD? Thanks for the reply man.

Adrian17 · August 30, 2018

Also I read the the ABS and P.Brake lights come on after a gearswap did this happen to you?

Donstar · August 30, 2018

Your 3.73 gear ratio is pretty respectable. I appreciate that larger wheels give a strong visual appeal but, as you are discovering, are hard on performance. Instead of re-gearing maybe consider a smaller rim/tire size combination that brings you closer to stock performance. There are 17 & 18 inch rims that will look great on your truck and accommodate beefier tires without rubbing or a significant power loss.

SierraHD17 · August 30, 2018

3.73 coupled with a 4L80e is not a desirable combo... you don't have enough torque multiplication and it's why GM handicapped the trucks such equipped to a 7900 lb trailer rating whereas the identical truck with 4.10 was 9900 lbs. Or 8300 and 10,300 respectively with my 04 as it's actually a light duty 2500... same truck as a 1500HD but that's another discussion. Like for a comparison go drive a 2007 and newer 6 speed HD with 3.73s and start the truck in 2nd gear everywhere... that's what it's like driving a 3.73 geared 4L80e truck.

4.10 works okay.. I honestly would love 4.56 in my 05 as it's always loaded with gear but I don't really want the 3000 rpm plus highway rpm's with a 30" tall tire. The first gear in the 80e sucks the big one.. it's one of the reasons the 6 speed is nicer to daily with. If it wasnt such a pain in the ass to do I would 6 speed swap my 05... the 04 maybe but it's got enough power and the 4L80e is more resilient to that lol.

Price I can't really help with as I dont live in the US and I dont know what shops down around you charge. Front and rears should be 10 or 12 hours labour max if that helps plus the price of gears, bearings and seals.

I do my own tuning so I adjusted my trucks accordingly after I swapped gears. You can get a decent custom tune and fix a few other things too.. do that with some gears and it will feel like you added 100 hp or more haha.

Edited August 30, 2018 by SierraHD17

Adrian17 · August 31, 2018

Yea I get you man, I may talk to some shops and ask what they think about it. Like I said im more than likely dropping two tire sizes since these tires rub. So I may just wait but ive always wanted to regear. As far as rpms I dont want 3k rpms either lol so I may go for the 4.10s. Any tunes you recomend? Im not sure on those things lol. Anyways thanks for the input man.

Adrian17 · August 31, 2018

11 hours ago, Donstar said:

Your 3.73 gear ratio is pretty respectable. I appreciate that larger wheels give a strong visual appeal but, as you are discovering, are hard on performance. Instead of re-gearing maybe consider a smaller rim/tire size combination that brings you closer to stock performance. There are 17 & 18 inch rims that will look great on your truck and accommodate beefier tires without rubbing or a significant power loss.

Yea I mentioned im going to drop about 2 sizes. And to be perfectly honest even with stock wheels my truck when towing would downshift on hills were as my brothers 2005 Ram 1500 5.7 with a 4 speed I believe, doesent downshift on the same hill and he has 20s also. Also I dont think the trucks have a huuge difference in power. Regearing was something ive always wanted to begin with just never got around to it. Thanks for the input man.

Edited August 31, 2018 by InvisibleBlack

SierraHD17 · August 31, 2018

If you are staying at 33 or so inches tall I would still do 4.56 over 4.10 but its your truck. I don't think 4.10 is honestly enough with a 30" tall tire... if 4.30's existed for these diffs I would have done those..... and stayed with the stock 245/75/16's. On the highway they pull fine but they are such a dead POS off the bottom compared to what they could be.

For a tune I haven't had any real good experiences with any tuner and that's why I own the software. Everyone here will say Blackbear because they are a forum sponsor but I would go with Klugg Performance over them. If you have someone local that would even be better!

Adrian17 · August 31, 2018

16 hours ago, SierraHD17 said:

If you are staying at 33 or so inches tall I would still do 4.56 over 4.10 but its your truck. I don't think 4.10 is honestly enough with a 30" tall tire... if 4.30's existed for these diffs I would have done those..... and stayed with the stock 245/75/16's. On the highway they pull fine but they are such a dead POS off the bottom compared to what they could be.

For a tune I haven't had any real good experiences with any tuner and that's why I own the software. Everyone here will say Blackbear because they are a forum sponsor but I would go with Klugg Performance over them. If you have someone local that would even be better!

Great thanks for your help man and yea the size im looking at is a 32.3 or a 32.9. Either way im regearing. Again thanks for the help man.

Formulabruce · September 5, 2018

Your 1500HD, while 8 lug, still has a "semi floater" 14 bolt, and not a Full floater like a 2500 or 3500 HD does.

This can make changing gear ratios easier for the side pressure on the carrier ( has a threaded ring).

Be sure you buy the right set for the semi floater rear end. May as well toss a locker in there while you are at it !

SierraHD17 · September 6, 2018

The semi floater has the threaded adjuster for preload and a shim on the drivers side of axle tube. It's an easy axle to work on as well... not as convenient as pulling the pinion snout out like a 10.5 but it's not hard either.