upgrade questions

[Chughart]

hey everyone, i have a question, im looking into doing some "upgrades" on the yukon (12 denali, stage 1 cam, tune). thinking of doing 3.73 gears but wondering if it would be possible to put 2500 differentials or what upgrades could be done to the factory diffs in the yukon? not looking to tow more just looking at making it more beefed up to take some strain off the driveline. i dont have the options to buy a 2500/3500 and need the space and like the yukon (shes paid off as well).

if you guys have any ideas that would be greatly appreciated.

 

[Chughart]

thinking of using these

2009-Up GM 1500 8.25"/8.6" Front & Rear Ring and Pinion Gear Package w/ Master Bearing Kits

GM 8.25"/8.6" Gear Package DescriptionPackage Includes:(1) Front 8.25" IFS Ring and Pinion Gear Set(1) Front Master Bearing Install Kit(1) Rear 8.6" Ring and Pinion Gear Set(1) Rear Master Bearing Install Kit- *Note: Rigid Axle's OE Dry 2-Cut is only available for rear 8.6" ring and pinions. The...

www.rigidaxle.com

 

[LsHart]

3.73 gears is the way to go. But imma 2 wheel drive guy. Imma let the 4 wheel drive guys chime in!

 

[SpareParts]

Is the Yukon an XL?
If so any Escalade ESV, Yukon XL or Suburban a 14 bolt, 9.5 ring gear SF rear axle would bolt in i believe. Front i believe you are stuck with the 8.5 ring gear.
I don't know about the short rig's

 

[Chughart]

ya its an xl. i figured the front diff is limited to the factory diff cause how its designed/mounted. im a capable of doing the gear swap on my own just didnt know if it would be easier or more beneficial to swap the entire diff out with something a bit bigger with the 3.73s already installed and then re-gear the front diff. im guessing though that just re-gearing the diffs will be quite a bit cheaper then getting the entire axle.

 

[Joseph Garcia]

Get yourself a used 14 bolt 9.5" gear rear axle from a 2WD Escalade of the same vintage from LKQ for under $500, and then rebuild it with 4.10 gears (you stated that you are capable). You could then put 4.10 gears in your existing front differential.

Your stage 1 cam setup with 4.10 gears and a new tune would really wake up your truck. And, the 14 bolt rear axle would certainly beef up your drivetrain.

 

[Chughart]

i think 4.10s would be a bit much for daily driving around where i live. while towing would be awesome but i think the 3.73 would be the best. which i could definitely replace the gears in a 9.5in 14 bolt but didnt know if it would be worth the hassle or am i over thinking this and just regearing my factory diff would be fine?

 

[Marky Dissod]

i think 4.10 would be a bit much for daily driving around where i live. while towing would be awesome but i think 3.73 would be best.

NO, 4.10 would be better than 3.73. You'd just spend more time in 6th, as well as in 5th, and downshift less often, assuming you're not a leadfoot.
For a potentially very small highway MpG penalty, your 6L80 would become stronger and last longer by shifting less often.
If you use your leadfoot to try to trade away some strength and durability, it'll still be stronger / more durable than 3.73, plus you'll gain MORE 'smiles per gallon'.
Or you could revise the 6L80 tune (shift pattern) to mitigate the small highway MpG loss.

Ever heard of the 2011-2017 Caprice PPV? Frequent the 'newcaprice' forum, you'll eventually learn that CAFE MpG pressures forced GM to settle for a 2.92 axle.
GM's original intent for the Caprice PPV was a 3.45 axle.

If you've the patience to do some maths, you'll eventually learn that
3.45 axle & 235/50R18 tires (27.25" tall) are near as makes no difference to 4.10 axle & 265/70R17 tires (31.60" tall).
Caprice PPVs, however, get 6.0L V8s and never tow anything.

Your Y-D XL weighs at least 1000lb more & has worse drag area than a Caprice PPV, and a 5.3L vs the PPV's 6.0L,
yet you're favoring CAFE MpG's opinion over GM's on which axle gear to choose?

Think about it, then reread @Joseph Garcia's post ... then reread @SpareParts' post.

 

[SpareParts]

I can testify to 4.10 gears.
Smiles per gallon goes WAY up.
Highway mileage seems to be about the same but i don't have enough highway miles to really compare yet.
Until i learn to not use the fun pedal so hard the fun juice is suffering im sure.
14 bolt, 9.5 SF is a lot stronger than a 10 bolt.
Driving seems like the truck drives smoother.
Swapping to 4.10's have been nothing but a + for me but i don't drive at 145mph either

 

[Marky Dissod]

Swapping to 4.10 has been nothing but a + for me, but i don't drive at 145MpH either.

FYI
Since you've enough engine power, you'd hit 145MpH in 5th @ 5400RpM.
With 3.08, with the same power, you'd hit 143MpH in 4th @ 5400RpM.
So you'd not only gain towing / hauling strength, you'd hit 143MpH quite a bit quicker with 4.10 vs 3.08.

EDIT: check my typos

 

[SpareParts]

FYI
Since you've enough engine power, you'd hit 145MpH in 5th @ 5400RpM.
With 3.08, with the same power, you'd hit 148MpH in 4th @ 5400RpM.
So you'd not only gain towing / hauling strength, you'd hit 145MpH quite a bit quicker with 4.10 vs 3.08.

That was a lil poke at @Doubeleive our resident speed demon.

 

[Doubeleive]

FYI
Since you've enough engine power, you'd hit 145MpH in 5th @ 5400RpM.
With 3.08, with the same power, you'd hit 143MpH in 4th @ 5400RpM.
So you'd not only gain towing / hauling strength, you'd hit 143MpH quite a bit quicker with 4.10 vs 3.08.

EDIT: check my typos

Not gonna happen, not with 4.10 you'll hit maximum velocity at maybe 130 if your lucky naturally aspirated. Horse power and wind resistance kick in

 

[Marky Dissod]

Not gonna happen, not with 4.10. you'll hit maximum velocity at maybe 130MpH if you're lucky, naturally aspirated. Horsepower and wind resistance kick in.

If a 5.3L Tahoe with 3.08 (a PPV) can hit 134MpH @ 5400RpM in 4th, then
a 5.3L bubba / XL w/ 4.10 should be able to hit 134MpH @ 5000RpM in 5th.

 

[Chughart]

i was under the impression that the 4.10s would be too much if i daily drive it. my commute to work is about 10ish miles of up and down a mountain and about 7 miles of highway and the thing gets 11ish mpg as it is i didnt want to lose more lol i do tow a 26ft camper about 6-7 times a year so the 4.10s would definitely help with that part of it and its a 6.2l btw. i guess what ill end up doing is just regearing my existing differentials. cheapest option and most straight forward since i dont have to remove the rear axle to swap the gears. i just dont want to "ruin" the way it drives and end up having to change the gears to 3.73 but same can be said about doing 3.73s and then regret not doing 4.10s lol ahhh decisions.

 

[Doubeleive]

If a 5.3L Tahoe with 3.08 (a PPV) can hit 134MpH @ 5400RpM in 4th, then
a 5.3L bubba / XL w/ 4.10 should be able to hit 134MpH @ 5000RpM in 5th.

like I said if your lucky and no headwind and running on fumes
it's called theoretical speed, it might not kick into that 5th gear

 

[Foggy]

i was under the impression that the 4.10s would be too much if i daily drive it. my commute to work is about 10ish miles of up and down a mountain and about 7 miles of highway and the thing gets 11ish mpg as it is i didnt want to lose more lol i do tow a 26ft camper about 6-7 times a year so the 4.10s would definitely help with that part of it and its a 6.2l btw. i guess what ill end up doing is just regearing my existing differentials. cheapest option and most straight forward since i dont have to remove the rear axle to swap the gears. i just dont want to "ruin" the way it drives and end up having to change the gears to 3.73 but same can be said about doing 3.73s and then regret not doing 4.10s lol ahhh decisions.

The carrier with the posi is the weak link in the 8.5" 10 bolt...
You can use an aftermarket carrier & posi unit to beef up your existing 10 bolt
and then choose what ever gears you'd like
If you are not towing or racing, this is the middle ground of going all out to the
14 bolt rear from the 2wd specd vehicles. As far as $$ goes, you could do this and
keep your existing 3.42 gear. You can just leave the front diff alone (assuming it's in
good shape)

 

[Chughart]

ya ive been contemplating regearing for some time now but dont know if it would be "worth" it given the upgrades ive done on the ole yukon. i just worry about the 8.5in being "weak" but i guess im just over thinking it. weve used the yukon for 3 years now to tow the camper and it does just fine so i guess ill just leave it alone and when or if one of the diffs starts to wear out or make noise ill just regear it then.

i just read your post @Foggy about gears and when i do end up doing the gearing will go with 4.10s since 3.73 doesnt seem like a good enough increase over 3.42 for all the work thats involved in changing the gears.

thanks guys for the info/help.

 

[Doubeleive]

meh the transmission is the weak point, followed by the g80
get the transmission built properly and then throw a eaton trutrac in the rear and your good to go.
I have my 6l80 built for 500hp and a eaton on the back and I can assure you I drive it harder than you ever will and it's not breaking
ya you could throw a 9.5" on the back but the awd is splitting the power 60/40 already so even though you could I don't think it is required.
money is better spent upgrading brakes and suspension, cooling the transmission If I didn't have the trucool and b&m deep pan on this thing it would be roasting the transmission

 

[Doubeleive]

even with that the transmission run's 180-ish in even slightly warm weather, If I didn't have the cooling it would be 230+ all the time