Which LSD?

kmanz1

Original poster
Member
Dec 31, 2012
12
Hello, folks,
Second post here. Appreciate all the help given on my first post.
My 2004 Envoy does not have limited slip, nor locking rear diff. This vehicle, as all 4wd's without such features, are an absolute piece of crap in snow, ice, especially where one tire is on dry pavement and the other is spinning. When people hear you say you have 4wd, they assume you can get through anything. What a false sense of security. Enough ranting. So, I was looking at the Eaton TrueTrac rear diff unit. I know it is not a full locker. I don't need that. I just want to have power to both rear wheels when needed. This will probably be good enough for 90% of the snow/ice conditions I will see. I don't do offroading. Just the occasional dirt/mud road to a fishing spot. Oh yeh. I also tow an 18 foot center console to saltwater fishing spots.
Your opinions welcome.
Thanks again, folks.
Ken
 

jimmyjam

Member
Nov 18, 2011
1,634
I installed a trutrac in my impala. Seems to be the popular choice for normal street use. Can't comment on what is best on snow or ice as I live in Florida
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Unfortunately, the only option available for your unique 8.0" rear diff is the Eaton G80 automatic locker. Once in a while you can find one on Ebay, but they're normally $600+ list price. For less than that, you can swap the entire rear axle in an afternoon for the upgraded 8.6" unit used on the XL/EXT trucks. If you buy it low mileage from a junkyard, it can cost $300-500. Just make sure to get the same gear ratio as you currently have. Use Car-Part.com--Used Auto Parts Market to get an idea what's out there, and know that they call the G80 a "LSD" even though it's not precisely limited slip.

The 8.6" rear end also accepts other locker options. You can find many possibilities at the granddaddy of differential and locker reference sites: Randy's Ring & Pinion. Randy's Ring & Pinion
 

kmanz1

Original poster
Member
Dec 31, 2012
12
Hey everybody,
Thanks for all your input. So, I thought there was one availlable. Thanks, JimmyJam.
So, knowing this, is this still my best option and does anybody have any 4wd experience with them?
Thanks,
kmanz1
 

Metsämies

Member
Mar 28, 2012
15
I plan to run a Truetrac

The Truetrac is a torque sensing diff, this means that if both wheels have equal traction they will each get 50% of the torque. When one wheel slips the majority of the torque goes the the wheel with the most traction. This works great in most applications, one down side is one wheel in the air. When this happen the wheel in the air has no "resistance" so it will spin it like mad unless it has a torque signal to bias off of. If this happens you are not out of luck this is the solution we learned in the AF.

"The HMMWV, or Hummer, uses Torsen® differentials on the front and rear axles. The owner's manual for the Hummer proposes a novel solution to the problem of one wheel coming off the ground: Apply the brakes. By applying the brakes, torque is applied to the wheel that is in the air, and then five times that torque can go to the wheel with good traction."

Now you will not get five times the torque to the wheel with good traction, the amount of torque applied to the traction wheel is determened by the bias ratio.

The Truetrac features torque bias ratios from 2.5 to 3.5:1 range.

[video=youtube;LTXvH3T8Bsg]http://www.youtube.com/watch?v=LTXvH3T8Bsg[/video]
 

Darkrider_LS

Member
Jan 25, 2013
9,332
Ok I noticed that the link for the truetrac indicates it was for an 02-06 Trailblazer. Would my '08 have an 8.0 or 8.6?
 

navigator

Member
Dec 3, 2011
504
Darkrider_LS said:
Ok I noticed that the link for the truetrac indicates it was for an 02-06 Trailblazer. Would my '08 have an 8.0 or 8.6?
As far as I know, all SWB with the I6 should have the 8.0
V8 or EXT models should have the 8.6.
 

Darkrider_LS

Member
Jan 25, 2013
9,332
navigator said:
As far as I know, all SWB with the I6 should have the 8.0
V8 or EXT models should have the 8.6.

Thanks for the confirmation
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
The easiest most cost effective route will be a used G-80 rearend. Simple bolt in and no cost for ring/pinion setup. Can also sell your current rearend to offst a portion of the cost.
 

Metsämies

Member
Mar 28, 2012
15
HARDTRAILZ said:
The easiest most cost effective route will be a used G-80 rearend. Simple bolt in and no cost for ring/pinion setup. Can also sell your current rearend to offst a portion of the cost.

Maybe I've had a few trucks with the G80, don't get me wrong I love it for what it is. The Truetrac has the same performance, but you don't have any springs or clutches to wear out. Don't forget the G80 in these 8.0-8.6 diffs have a habbit of grenading under heavy use with oversize tires. I havn't seen many grenade in the 2500-3500 series trucks but they are much stronger because they are much bigger. The truetrac's helical gear design eliminates the need for wearable parts, this means maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well.

They are both made by Eaton so both good in my book. A few years ago I went to buy a rebuild kit for my G80 in a 1998 K1500 with a 6.5 Diesel and the 9.5" diff I was told about the trutrac as an alternative. It gave me the same traction except in one situation as mentioned earlier. I like them better because its ALL gear, not only that but all H1 hummers run this STYLE of diff they are strong and reliable.
 

HARDTRAILZ

Moderator
Nov 18, 2011
49,665
Metsämies said:
Maybe I've had a few trucks with the G80, don't get me wrong I love it for what it is. The Truetrac has the same performance, but you don't have any springs or clutches to wear out. Don't forget the G80 in these 8.0-8.6 diffs have a habbit of grenading under heavy use with oversize tires. I havn't seen many grenade in the 2500-3500 series trucks but they are much stronger because they are much bigger. The truetrac's helical gear design eliminates the need for wearable parts, this means maintenance free traction recognized not only for its toughness, but its smooth and quiet operation as well.

They are both made by Eaton so both good in my book. A few years ago I went to buy a rebuild kit for my G80 in a 1998 K1500 with a 6.5 Diesel and the 9.5" diff I was told about the trutrac as an alternative. It gave me the same traction except in one situation as mentioned earlier. I like them better because its ALL gear, not only that but all H1 hummers run this STYLE of diff they are strong and reliable.

I still stand by what I said. I have used, abused g80s for decades. I put my stock one in the TB thru hell and it didn't miss a beat even w 33s and hitting offroad parks all over. I have also destroyed g80s and Detroit's n about every other diff.

I said simple and cost effective. I run a lunch box locker in a 9.5 but have 5 times the cost of used g80 rearend in it.
 

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