8.6 gear swap?

fr34kout

Original poster
Member
Jan 6, 2012
662
Thought about this in the past, I have a 8.6" 3.42 rear end on my Denali with the G80. I was thinking about trying to find a TBSS rear axle for the 4.10 and 9.5", but then a friend suggested just regearing it.

Took a look on Rock Auto and saw a 4.11 Ring and Pinion gear GM part for my 8.6" rear end, assuming it's out of a Yukon. Was only around $350 shipped.

Was doing some research and it seemed like people have talked about this before but there was no definitive answer. Would I be able to use these to convert my rear end to 4.11? If so what else would I need? I read something about a master rebuild kit, anything else required? Also thinking about shortening the axle 1" on each side since I plan to bag it later (still not 100% sure it will get done)

As far as experience I've been wrenching on my own cars for the last 4-5 years but haven't done anything major like this. Got a friend that's going through an automotive program at a community college and I believe he's doing transmissions next semester. Would it be possible for us two to tackle this or is it something that should be done at a shop?
 

navigator

Member
Dec 3, 2011
504
I've done a good bit of wrenching and a few engine swaps but gears is something I would try to find someone else to do.
I understand it requires special tools and they can be difficult if you have never done it before.

I know Fishsticks has done it before, there may be others, maybe they can chime in.
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
There are a few web sites, and Randy's Ring & Pinion sells a book, that explain the process. Then you can evaluate how the job matches up to your skills and experience. You can spend $300 on tools, or $300 at a shop if you have a reputable driveline mechanic in town, and get it done.
 

TXBlazer

Member
Nov 21, 2011
533
Cypress, TEXAS USA
If you have the time...do some research and looking sround for the SS rearend, you will be glad you did, basically a bolt on unit that is ready to turn!! I have seen them on Craig's List and Ebay for $400.
 

navigator

Member
Dec 3, 2011
504
0r if you can get the 9.5 for $400 on CL or Ebay, you can then likely sell your 8.6 for $400 as well.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Shipping is the real killer there, extra $350 to ship it to me haha. The prices I was seeing while doing research the other night was pointing towards more of the $900 ballpark for an SS rear end. If I can find one locally for around the $400-500 price point that would be way simpler. I got a few other things I need to do before I can worry about this, so I have time to search for one locally. Just wanted to get some advice ahead of time. Thanks for all the responses guys, I really appreciate it :thumbsup:
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
I had to get a bastard Ujoint and have my driveshaft shortened for my SS rear swap, but everything else bolted on.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
$85 I think... Had a small local shop shorten and balance it. The Ujoint is $25 ish as well.
 

jham

Member
Nov 20, 2011
1,334
fr34kout said:
How much did it run you to shorten the driveshaft?

when I did mine I had to take 2 inches out of my drive shaft it ran me $ 60 . Hardtrailz has longer control arms and if I recall from his thread he had to take 1/2 inch out of his
 

fr34kout

Original poster
Member
Jan 6, 2012
662
One of the things I need to do before I can mess with the rear end is to actually buy the adjustable panhard and trailing arms. I'm going lower though not lifted, not sure if that means I have to make them longer or shorter than stock lol
 

Pittdawg

Member
Dec 5, 2011
538
fr34kout said:
One of the things I need to do before I can mess with the rear end is to actually buy the adjustable panhard and trailing arms. I'm going lower though not lifted, not sure if that means I have to make them longer or shorter than stock lol

I just swapped in 4.10's in place of my 3.42's in my 8 inch rear. Couldn't be happier. $677 for all parts and labor. Well worth it, in my opinion.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Did you notice a big difference in off the line acceleration? Looking for better acceleration and hopefully a little better mpg around the city. Mostly for the acceleration though lol, all the sounds in the back is weighing me down more than I thought. Have a PCM for less intake and tune, but got beat by about 1 car length by my friend in his dad's v6 xterra. 1/4 mile times say I should have been half a second ahead of him but nope lol
 

Pittdawg

Member
Dec 5, 2011
538
fr34kout said:
Did you notice a big difference in off the line acceleration? Looking for better acceleration and hopefully a little better mpg around the city. Mostly for the acceleration though lol, all the sounds in the back is weighing me down more than I thought. Have a PCM for less intake and tune, but got beat by about 1 car length by my friend in his dad's v6 xterra. 1/4 mile times say I should have been half a second ahead of him but nope lol

Huge difference but I have a 4.2 vs. your 5.3 so my engine was really lacking in the low end torque dept. I honestly believe no 4.2 should come without 4.10s. I have never driven a 5.3 though so its really hard for me to guess what type of difference you would see.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Just hearing that gives me a lot of hope. I think just noticing a huge difference will be the same regardless of engine output, possibly even a little more so on a 5.3 lol

Edit: Oh and since your 4/2 is an 08, the power difference isn't too drastic. I think you guys have like 291/300 and we have 303/330? Something like that
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
jham said:
when I did mine I had to take 2 inches out of my drive shaft it ran me $ 60 . Hardtrailz has longer control arms and if I recall from his thread he had to take 1/2 inch out of his

My arms are half inch longer and the driveshaft was shortened 1.5 inches.
 

fishsticks

Member
Nov 21, 2011
433
If you have a Harbor Freight near to you, all of the specialty tools you need can be had for a little over $100.

in-lb torque wrench - $20
ft-lb torque wrench - $30
Digital Calipers - $10
Bearing Puller - $40
Dial Indicator with magnetic base - $20

Everything else is simple hand tools (or air tools if you have them).

A quality gearset is going to run you around $200 and add another $100 for a master install kit (comes with all new bearings. shims, new crush sleeve, gear marking compound).

After that it's all patience, attention to detail, and researching BEFORE you start the process. I did my first two gear setups ever on my TB. 20K miles and a LOT of offroad abuse later they are still quiet as a mouse. Now I do gear setups for friends too. I've made back the money I spent on tools.

In case you are wondering, 4.56 gears will turn 35" tires from a stop on dry pavement with the I6. Your G80 may not be happy about trying that though. I put a real locker in mine.

Hawaii is expensive as hell, but you already knew that. :wink: DIY if you can.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Unfortunately, no Harbor Freight in Hawaii but I have a few friends I could borrow torque wrenches from (at least the ft/lb wrench). With the price of the rebuild kit with gears and specialty tools, it looks like it might end up making more sense to just find an SS rear end. Bigger, stronger, and it sounds like the G80 locker might not be the best choice especially since I plan to work on the engine later.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Not needed for SS rear.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
What's not needed, the G80? That's what I was getting at, if I get an SS rear I don't have to worry about the G80
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
fr34kout said:
What's not needed, the G80? That's what I was getting at, if I get an SS rear I don't have to worry about the G80

Case spreader.

SS have a g86 limited slip not a g80.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
HARDTRAILZ said:
SS have a g86 limited slip not a g80.

That's what I was getting at lol. Wouldn't need a case spreader because I shouldn't have to open it up if I got a complete axle right? If anything just remove the cover, clean up everything and fill it back up with some good 75-90
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
fr34kout said:
That's what I was getting at lol. Wouldn't need a case spreader because I shouldn't have to open it up if I got a complete axle right? If anything just remove the cover, clean up everything and fill it back up with some good 75-90

No. The SS rear does not need a spreader for any work. I took the g86 out of my SS rear for a different carrier n locker.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Ahh got it, even though I don't know what AAM axles are rofl. I've messed with sounds, electrical, suspension, slight motor work, but this is all new to me lol
 

fishsticks

Member
Nov 21, 2011
433
fr34kout said:
That's what I was getting at lol. Wouldn't need a case spreader because I shouldn't have to open it up if I got a complete axle right? If anything just remove the cover, clean up everything and fill it back up with some good 75-90


You will still need to have your driveshaft shortened and rebalanced if you use an SS rear end, as well as the off-size U joint Hardtrailz mentioned.

Ahh got it, even though I don't know what AAM axles are rofl. I've messed with sounds, electrical, suspension, slight motor work, but this is all new to me lol


AAM is an axle manufacturer, like Dana. All our trucks use AAM axles.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
Locker is mainly useful for offroading correct? If I'm never going to ever do any off roading (4" drop currently) and plan on eventually working on the engine later (cam, heads, F/I when I can afford it), would the LSD in the SS be a much better choice than sticking with my current G80 and regearing it?
 

fishsticks

Member
Nov 21, 2011
433
fr34kout said:
Locker is mainly useful for offroading correct? If I'm never going to ever do any off roading (4" drop currently) and plan on eventually working on the engine later (cam, heads, F/I when I can afford it), would the LSD in the SS be a much better choice than sticking with my current G80 and regearing it?


Lockers are for traction. Offroaders and some drag cars use them(I think some of the drift crowd use them too). They are handy to have for anyone who drives in crappy weather. LSDs have nicer street manners than most lockers but are clutched based and wear out.

IMO either is better than the G80. G80s like to explode.
 

fr34kout

Original poster
Member
Jan 6, 2012
662
The worst conditions I have to deal with is rain, I could definitely see the benefit for the states that get snow and ice though.
 

fishsticks

Member
Nov 21, 2011
433
fr34kout said:
The worst conditions I have to deal with is rain, I could definitely see the benefit for the states that get snow and ice though.


Lack of one tire fire is good even in dry weather. Too many burnouts on your G80 will inevitably be followed with a *POP* and most likely a hole in the cover. LSDs and real lockers are far more durable under shock loading.
 

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