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Anyone put 3.73 gears with 6.2L/8Speed?

Anyone put 3.73 gears with 6.2L/8Speed?

Postby DenaliHD66 [OP] » Feb 17 2017, 4:07am

My 2015 Sierra 6.2/8Speed has the Max Trailer and 3.42 gears. I was wondering if anyone has upgraded to the 3.73 gears. Anyone have any feedback as to what improvements I'd see? I know I'd lose some MPG but for the sake of being able to accelerate even faster and get up to speed, I'm interested in possibly doing this mod.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby MIKE91B » Feb 17 2017, 4:32am

Swing bigger go 4xx or more with that trans. That little jump won't do crap trust me. I did 3.08 to 4.10 on a 15 5.3l 6sp and it didn't equate to anything worth talking about. An increase in power will net better results. The cost benifit analysts doesent work in your favor at all.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby Copperhead » Feb 17 2017, 8:51am

The only way to get the cost benefit is if it was an option from the factory. Given the nature of how GM markets their 1500 series pickups and what they can do, it is surprising that they don't have something like a 4.10 option for those that can benefit from it. After many years of pickups, I have become convinced that 4.10 is just about the best overall ratio for anyone who does more than just use their pickup as a car on steroids. I have been using 4.10 ratios in a lot of stuff since the early 70's. And it is one of the reasons I have a 2500 now.

MPG loss is more about how the vehicle is driven than the rear ratios. I only lost 1 mpg average between a '13 1500 5.3L with 3.42 and my '15 2500 6.0L with 4.10 which is considerably heavier. That 1500 was the first time is many years I ventured out of the realm of 4.10 diffs and I learned my lesson not to ever do it again. And I don't throw on big tires or do other things like that. Just basic pickup use with regular hauling from time to time and a little towing occasionally.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby Jgduran » Feb 17 2017, 3:34pm

I agree with the others. Going to 3.73 wont be a noticeable difference. I would at least go to 4.10 and if you have larger tires then you could go to 4.56. Overall your not going to notice much of a difference. The 8spd is is just geared lower and has more gears to choice from so you probably wont notice the difference beside your speedo being off. But another good thing about going to a lower axle ratio is it will help extend the life of your transmission.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby DenaliHD66 [OP] » Feb 17 2017, 4:43pm

The one site I was looking at had 3.73's as the highest available for the axle sizes on my truck (8.25" front, 9.76" rear) so I didn't know there would even be a 4.10 option. I'll be running 33's in the near future. Transmission needs tuned for sure, I want more power for sure and just less strain on the trans to be the center of the gearing. I break and spin both rear tires loose very easily with the stock setup and tires, and I even have 160 lbs of salt bags in the bed for extra winter traction. With 4.10s I could probably spin in 4wd on a nice launch. Will that limit my overall speed capability though? Like when I get the governor removed, I won't have any problem hitting 110-120 without the revs being too high?
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby MIKE91B » Feb 17 2017, 9:00pm

The drive shafts become the limiter for top speed. The don't like to go over 100 with factory gears and they hate doing it with 4 series gears.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby DenaliHD66 [OP] » Feb 17 2017, 11:49pm

MIKE91B wrote:The drive shafts become the limiter for top speed. The don't like to go over 100 with factory gears and they hate doing it with 4 series gears.


Ah okay. I want mine to be a bit of a balance between acceleration and still being able to hit 120. I may go with the 3.73s and tune it.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby Rambodog » Feb 17 2017, 11:55pm

3.73 and a tune looks something like this :D
https://www.youtube.com/watch?v=rbO81-vF_jw
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby 6.2AllTerrain » Feb 18 2017, 12:11am

I have 4.88's with a 6-speed and 6.2L I would go with 4.10's at a minimum.
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Re: Anyone put 3.73 gears with 6.2L/8Speed?

Postby DenaliHD66 [OP] » Feb 18 2017, 2:17am

If I get 4.10s it looks like I'll have to get a bigger rear diff cover too, which was already on my list of upgrades anyway.
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