gu6 question

[silvertb4x4]

I have the gu6 3.42 how do I tell if I have a posi or not??

[FireFighter7]

its the G80 code the rear diff locks at high RPMS.

Ive gotten mine to lock a few times but you need to get the RPM's high

Also Most recommend it for Off roading.

Hope this helps you out.

[RayVoy]

Yep, FireFighter7 is right, it is the G80 code, look on the glove box door.
But, it doesn't need high rpm to lock. It senses a difference in right/left axle rpm and locks. This difference is only 10 rpm and the diff will lock. ie: the right on ice and the left on dry pavement and you are stopped; power the truck and when the spinning left hits 10 rpm, the G80 will lock the diff.

BTW, we have a locking diff not a limited slip diff (posi is a limited slip diff)

[silvertb4x4]

that sucks they should put posi's in everything. They perform way better in the snow. Hell my dodge ram was 4x4 with posi rear and i never even had to put it in 4x4.

[Robert1101]

that sucks they should put posi's in everything. They perform way better in the snow. Hell my dodge ram was 4x4 with posi rear and i never even had to put it in 4x4.
I think there is a dodge forum if you google it. :)

[silvertb4x4]

Chevy will out last a Chrysler product anyday! Nor will any of the big 3 figure out how gm gets the best mpg..

[RayVoy]

that sucks they should put posi's in everything. They perform way better in the snow. Hell my dodge ram was 4x4 with posi rear and i never even had to put it in 4x4.I've had a lot of GM posi rears, and this is the 1st locker. I had very few problems with the posi, the gm additive is no good and I've used the Chrysler additives, but all and all said the posi works good. However, the locking rear gives you the freedom of the open and the advantage of the full lock, I think it's a great rear-end.

[the roadie]

...This difference is only 10 rpm...Actually, the trigger speed is 100 RPM, and the locker effect goes away at 20 MPH. Oooops. But that's data from the G80 automatic locker used in the NON-SS trailvoys. I don't have data on the posi used in the SS. Sorry.

[WOOLUF1952]

I've had a lot of GM posi rears, and this is the 1st locker. I had very few problems with the posi, the gm additive is no good and I've used the Chrysler additives, but all and all said the posi works good. However, the locking rear gives you the freedom of the open and the advantage of the full lock, I think it's a great rear-end.

:hijacked Did you use just a pack of additives in the rear diff. or all Chrysler fluid?

[silvertb4x4]

so the gu6 is somewhat a posi? im getting lost

[silvertb4x4]

i need posi additive aswell ? when i change fluid?

[RayVoy]

Actually, the trigger speed is 100 RPM, and the locker effect goes away at 20 MPH. Oooops. But that's data from the G80 automatic locker used in the NON-SS trailvoys. I don't have data on the posi used in the SS. Sorry.Thanks Bill, I new 100, but typed 10, sorry. I think he has a non-ss as his name uses 4x4.

:hijacked Did you use just a pack of additives in the rear diff. or all Chrysler fluid?
Just the small additive bottle, 2 or 3 oz.

so the gu6 is somewhat a posi? im getting lostThe posi uses clutches that centrifugally engage and release. The locker uses mechanical engagement. They are not the same, but they act the same (somewhat).

i need posi additive aswell ? when i change fluid?No, just use the gm suggested synthetic fluid

[RayVoy]

The posi uses clutches that centrifugally engage and release. The locker uses mechanical engagement. They are not the same, but they act the same (somewhat).Sorry silvertb4x4, I just re-read this and I gave you the wrong info.
A posi is a limited slip rear-end, the left and right axles are always connected together with a friction clutch. When driving in a straight line, the left and right axles (and their wheels) receive equal power. When the vehicle turns, the outside wheel turns in a wider arc than the inside. This requires that the inside axle turns fewer rpms, the clutch plates allow for slippage (hence the name) and the inner axle turns slower.
The difference between the 2 axle types, the posi is locked all of the time and slips when required; the locker is free most of the time and locks when required

[silvertb4x4]

Ok gotcha You guys rock, :thumbsup:

[blueblazer5_3]

OK, look in your glove box at the build codes...They are three letters and number combos. It is a silver sticker. If the code G80 is present next to the GU6 ( or in the same area, the codes are very close together) then you have the LOCKING DIFFERENTIAL....The standard TB or Envoy did not come with the Limited slip. Only SS TB have the limited slip.

Limited slip works in this manner:

The wheels start to spin, the clutches grab due to spring pressure in the clutch pack in the rear (I know, very technical), and allow power to BOTH wheels ---BUT--- most power goes to the wheel with the greatest ability to spin....not good on a hill in snow or dirt, the wheel with the least traction will just keep spinning.

The G80 or LOCKING Differential works like this:

The wheels start to spin...The spring loaded detent (a piece of metal) sees a 100 rpm difference between the left and right axles and sets the "piece of metal" to lock the two sides of the carrier (what holds the ring gear making the car move) and provide 100% power to BOTH wheels...no slip, just 100% power to the left and right wheel. This allows either wheel to gain traction and get out of a bad situation. Now, this will not work at speeds over about 25 mph, have had it work at 25 so I know it does that.

The Positraction rear as Gm puts it, is a limited slip. A true locker will feel like 4wd is engaged when turning when it is LOCKED. The locker also disengages itself when the rpm difference is less that 100 rpm.

Hopes this helps....


Don