2020 Suburban LT upgrade to 4:56 gears

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rediron

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I have a 2020 Suburban LT 4wd lifted with 35x12.5/r20 tires.

RPO codes say the stock ratio is at 3:08 with stock tires of 265/65/r18 and I'm upgrading the gears and ratio... I'm thinking of upgrading to 4:56 nitro gears, but is this overkill? My math shows it's a little high, but i've read 35s w/ 4:56 is an awesome and fun combo.


There's only mild towing, but lots of mountain driving with the burb currently, but don't care about MPG. Only mod currently done that would be related / help is the "pill flip" but with new thermostat internals in the bypass and not just "flipped".


Also, I have a stock limited slip diff, can that be reused with the new ring / pinion or is it gear specific?


Any help is greatly appreciated!
 

Tiki

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You read about this for older generation trucks with different overall gearing. 4.56 would be overkill.
 

Doubeleive

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if you do 3.73 you can just swap the front diff and do the ring & pinion on the back, front diff used is around $600
4.56 is way overkill, it's not a rock crawler.
 
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rediron

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Swap the front diff from what donor truck? Yep, you guys are right and from playing around with calculators and people I've talked to everyone is saying 3:73 or at the very max a 4:10 ratio.

The problem I've been finding (and i've called quite a few pros in Vegas and SoCal now) is that no one wants to even touch re-gearing a newer 2018+ 4wd Burb, Tahoe, Silverado etc due to the front diff requiring a "case break" and the issue is I guess the ring is welded in the front diff.

The rear is no problem -- even though a lot of shops thought a rear 9 1/2 inch ring in a 12 bolt housing was odd, but the front diff being welded is causing lots of shops to not even want to touch the job
 

swathdiver

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I have a 2020 Suburban LT 4wd lifted with 35x12.5/r20 tires.

RPO codes say the stock ratio is at 3:08 with stock tires of 265/65/r18 and I'm upgrading the gears and ratio... I'm thinking of upgrading to 4:56 nitro gears, but is this overkill? My math shows it's a little high, but i've read 35s w/ 4:56 is an awesome and fun combo.


There's only mild towing, but lots of mountain driving with the burb currently, but don't care about MPG. Only mod currently done that would be related / help is the "pill flip" but with new thermostat internals in the bypass and not just "flipped".


Also, I have a stock limited slip diff, can that be reused with the new ring / pinion or is it gear specific?


Any help is greatly appreciated!
4.56s and 35s are the equivalent of 4.10s with your stock tires.

Which transmission do you have?

The 3.08 carrier is not compatible with other, higher numerically gears. There are adapters but not sure how strong they are.
 
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rediron

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if you do 3.73 you can just swap the front diff and do the ring & pinion on the back, front diff used is around $600
4.56 is way overkill, it's not a rock crawler.

It looks like a 2020 Silverado 1500 had 3:73 as an option with the 5.3L / 6 speed. Since the 2020 Suburban is a 5.3L / 6 speed 6L80 and its basically the same frame as a Silverado 1500, a front diff new or used from a 2020 silverado with 3:73 should be pretty much an easy swap out?
 

Doubeleive

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It looks like a 2020 Silverado 1500 had 3:73 as an option with the 5.3L / 6 speed. Since the 2020 Suburban is a 5.3L / 6 speed 6L80 and its basically the same frame as a Silverado 1500, a front diff new or used from a 2020 silverado with 3:73 should be pretty much an easy swap out?
yep they are the same as long as it is 1500/1500, 2015-2020 would be the same fitment, you just have to verify the rpo code is the one you need, there are quite a few on ebay shipped for like $600-650. I plan on changing my silverado from 3.08 to 3.73 eventually. I can just buy the front diff and the rear ring&pinion I will upgrade the rear carrier at the same time.
 
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rediron

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yep they are the same as long as it is 1500/1500, 2015-2020 would be the same fitment, you just have to verify the rpo code is the one you need, there are quite a few on ebay shipped for like $600-650. I plan on changing my silverado from 3.08 to 3.73 eventually. I can just buy the front diff and the rear ring&pinion I will upgrade the rear carrier at the same time.
Awesome, thanks for the info. Yeah for the front diff, this looks like its the easiest (and cheapest) route
 

Crispy816

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Has this swap happened yet? If so, how did it work out? I have a 17 Tahoe on 33's with the 3:08's and cant stand them even with a tune. Please update when you have a sec. Thanks in advance.
 
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