I think my G80 is not G80ing...

[fishsticks]

Observe...




Dust cloud only from the right rear the two times I start to lose traction.

I was also stuck in snow the same day briefly and only got spin from the right side.

I have not jacked the rear end up yet to check if both wheels spin...

Any ideas as to what I could/should be looking for?

(Yes, I'm positive I have a G80)

[bgwolfpack]

Someone will answer this for you definitively but I thought I saw it lock up after spinning. Isn't that how they work?

[HARDTRAILZ]

It should spion one a little then lock...Can you feel it locking in?

I have gotten in a weird spot and never had it lock, but everywhere else that day it did.

[The Roadie]

It should lock up within one revolution with a 100 RPM (~ 2 revs per second) difference. You can spin it by hand fast enough to test it when jacked up. Spinning rocks out the back with one tire only should not be possible. You might break both loose, but not just one. And if both rears lock up and start spinning, the transfer case should transfer torque forward and the fronts should start pulling while the rears slow down.

[Trail X]

I'll agree with Kyle... It works for me most of the time, but I too have had certain situations arise where it doesn't want to lock up for me.

At around 25 second below you'll see the G80 how it should work. It doesn't always.

[fishsticks]

Just came in from jacking up truck. Put it in drive and let rear wheels spin. I can stop the left wheel with my foot. Partially set e-brake to simulate low traction scenario. Right wheel spins, left doesn't. Give a little gas to get wheel revs up....nothing. I do however hear what sounds like something engaging as the speed increases. Almost sounds like it's not engaging fully.

Fluid was just changed 5k miles ago. Old fluid didn't look bad. I had the diff cover off, nothing seemed out of sorts.

I'm good with motors... The innards of rear-ends I'm not so familiar with. Anyone have some insight?

[fishsticks]

I've been looking at this picture.



Looks like part(s) number 11 is responsible for the "locking" part of the locker, correct?

I watched some videos that detailed how the G80 engages... the sound I'm hearing when the diff is "engaged" almost sounds to me like worn splines. It is not loud at all, and I've never noticed it from inside the truck. Perhaps at some point the shock of engagement took the splines off the left side axle?

I'm just speculating now... any input is welcomed. I'm pulling the cover tomorrow.

[bgwolfpack]

Donny, I don't think you have a problem judging from being around your truck the other day. It's good you're going to pull the cover and look. I hope you find nothing but stinky oil.

Not that it matters, because of the OS, but you might want to take pics for others to spy. Let me know if you need any help getting anywhere if there is a problem. I would be surprised though.

[The Roadie]

You've got the initiator part identified. What might have happened is an engagement at too high an RPM. There are tangs on the clutch plates designed as mechanical fuses to shear off and make sure it doesn't destroy the entire carrier. I broke my carrier (item #1) and then the fragments broke everything else.

[fishsticks]

So my possible points of failure (for an otherwise smooth and flawlessly operating diff) are parts 11 and 18?

I guess I'm still a little foggy on what magic happens once the weights move that actually "locks" the two axles together.

[The Roadie]

Memorize this:



There will be a test if I'm your trail boss.

[fishsticks]

PERFECT! I completely get it now.

Now... wonder what I'll see tomorrow.

[fishsticks]

Here we go...




This fluid seems awfully black for 5k miles...


... and the winner.



See the problem?



So... it looks fixable. I can buy the governor assembly as a separate unit. It's around $100 shipped from gmpartsdirect. It looks like I may even be able to replace the weight assembly without pulling the whole carrier out, just by removing the passenger side cap. The missing tooth is the one that normally grabs when the locker engages and the rest of the teeth aren't in great shape either... so I can't really figure a way to put enough force on the mechanism right now to get it to engage to make sure the clutches aren't toast. Ideas?

I'm a little preturbed by the blackness of that gear oil. I've done a lot of research over the last day regarding G80 failures. I haven't been able to get a good picture of people who've had clutches go bad vs people who've had similar problems to my own. It SEEMS like if my G80 has been unlocked for awhile (I suspect this has been a problem for a LONG time) then the clutches shouldn't be in jeopardy.

I guess I'm going to try and find a way to get that cam to lock in so I can see for sure if the axles lock together.

[bgwolfpack]

So what have you decided to do?

[Trail X]

So the governor is missing one of its 6 (or so) teeth? The governor will lock up in both directions of spin (left or right wheel spinning) so if the other teeth are intact, it should lock up on the opposite side. You should see if you can lock it using the opposite wheel [than you've been trying] as the spinning wheel.

[fishsticks]

What the pic doesn't show is that the other teeth on the governor are there, but in terrible shape as well. I was able with some fiddling to get both wheels to spin together, although I obviously wasn't able to generate enough force to really test them out.

I ordered a new governor assembly (PN 12471530) from gmpartsdirect this morning. I'm going to attempt to pull the right side bearing cap and knock the bushing out far enough to remove the old gov assembly. If that doesn't work I'm pulling the carrier.


Black fluid, but no real foreign matter in it. No chunks milling about. It's drivable in the mean time at least.

[HARDTRAILZ]

Glad its drivable and you can get it fixed yourself. I checked mine today and it locked it everytime I thought it should.

Good luck with getting it done.

[fishsticks]

FedEx has a tracking number for me. I should hopefully have both rear wheels under power again a week from tomorrow.

[fishsticks]

So that I am prepared... can someone with a Helm manual give me the torque specs for the passenger side carrier bearing cap?

[The Roadie]

55 ft-lbs

Remember, the COVER bolts are only 20 (18 for the 8.6"). Don't ask me how I know.