Anyone upgrade their axle ratios to 3.73's?

[Doubeleive]

I can make a direct comparison, given the two vehicles in my sig.

The Suburban is 1000 lbs heavier and has 50 fewer HP, but also has a tune.

The Denali jumps out to a quick lead, but then is unable to walk away. The Suburban stays about two car lengths back right up to 100, then, of course, overtakes and walks away.

But personally, given the cost of regearing (not something I can do myself), I wouldn't do it unless it was at least a double jump. Cost/benefit doesn't make sense. 3.42 to 3.73 just isn't worth it. 3.42 to 4.10, yeah, that might be worth it.

Of course, given my Denali already gets frightening mileage with the 3.42s (and needs premium), the mileage running 4.10s would be downright terrifying.

really? your 6.0 burb is walking away from the 6.2 sierra? that doesn't sound right at all, my 6.2 denali hit's 100 in 3rd gear then keeps on going

 

[intheburbs]

really? your 6.0 burb is walking away from the 6.2 sierra? that doesn't sound right at all, my 6.2 denali hit's 100 in 3rd gear then keeps on going

The Denali is governed to 99. The Suburban isn't.

 

[Doubeleive]

The Denali is governed to 99. The Suburban isn't.

that explains it....

 

[gmartin1215]

4.10s on stock size tires and the 6L80 would turn 2,098 rpms @ 70 mph and 2,248 rpms at 75 mph. Some of GMs 2500 and 3500 gassers run 4.10s with the 6L90 so they were made for it.

I considered it, saw a lowered and modified Sierra just leap off the line but both Sierras spin the tires off the line on the street already. One of them has stock size KO2s and 3.42 gears and the other the 3.73s on 35" tires. That and the higher rpms are why I'm going to stick with the 3.73s.

@B-train Consider the difference between your Dad's Silverado and a 2009+ Silverado equipped as shown.

View attachment 383962View attachment 383963

Now here are the effective ratios for each gear with the ones Sparky is considering:

View attachment 383964View attachment 383965

Now also consider this, there's a young man sweet on one of my daughters who comes around with a Ram 1500. He's been victorious in several 0-60 runs at the street drags. The 3.73 geared Sierra on 35s gets him off the line but he quickly runs her down. The motor's in each are similar power wise so I endeavored to find out why and here is what I discovered:


View attachment 383966

Look at that first gear ratio! In order to compete with that gear wise we'd have to go with 4.56 gears. We installed the BlackBear tune that Justin sent over yesterday and when my daughter got back from an impromptu drive she was all smiles and said it went "zoom, zoom" like never before! Fun stuff!

@swathdiver where did you find these tables with all the ratios?

 

[CaptainAmerica1]

He’s good at maths…

 

[swathdiver]

@swathdiver where did you find these tables with all the ratios?

Lots of research and having fun with excel. I made them.

 

[Fubar0715]

Lots of research and having fun with excel. I made them.

Handy and smart - we can only strive to be like you!

 

[Dustin Jackson]

@Sparkyz07Denali I believe I have 3.73 in my 08 Z71 Tahoe. MPG is not the best. I get about 18mpg at 65MPH and about 16mpg at 75MPH. This is with 33x10.5 tires and 3 inches of lift. I average 13.5mpg

 

[swathdiver]

Oh I may go to 4.10’s then. And you don’t buy a Denali because you wanna conserve gas. At least I didn’t.

I used to have a ‘13 SS Camaro, bought it new. 2yrs later was stolen. Life has happened. And I’m in a spot where I need to haul 4 English mastiffs. So I have a Denali. And I can build it with the similar of not the same mods I did to the Camaro (which had 515rwhp)

This is amazing info. Thank you. Still leaning toward 3.74’s since I drive almost an hour one way to work.
Then again. It’s a 4 day work week. (I work 12’s) so it could still work with 4.10’s

Done anything yet? I'm about to get started on mine, been collecting tools and parts.

 

[B-train]

@swathdiver did you ever change up the gear ratios? I've been toying around with changing my 2008 Denali to either 3.73 or 4.10 and just make it a true mountain climber. I think these gear choices may be a better fit with not having 4-LO.

Also, how do you plan to work around the front differential if you drop in a unit from a truck with selectable 4WD?