Thump thump, G80 and confusing gear oil

[Pinger]

I'd expect the Gov-Lock to engage if one wheel turns ~100 rpm faster than the other. Maybe your clutches are as worn-out as mine. (Or worse.)

Mine does just that. With one wheel (just and no more) raised from the ground and the other stationary a blip of throttle will lock the diff and pull it off the jack.

 

[Schurkey]

Mine does just that. With one wheel (just and no more) raised from the ground and the other stationary a blip of throttle will lock the diff and pull it off the jack.

I gotta try that with mine...

 

[Tnman54]

When you talk about drag forward vs. no drag backward--is that you spinning the drum by hand, or is that driving the vehicle, shifting between forward gear and reverse gear?

Is there a chance that this is a transmission problem, where the trans binds-up and doesn't transmit power properly?

driving the truck is when it happens.

 

[Tnman54]

as i mentioned before, while on jack stands the passenger side turns but not the drivers side, I even got it up to 60mph and never any movement from drivers side, so locker must not be working for some reason.

 

[Schurkey]

driving the truck is when it happens.

I'd be considering potential transmission problems. How's the fluid level and condition?

I had a 4T60E that dragged terribly in OD, then shifted back to 3rd gear. Trans did not last long.

 

[Pinger]

as i mentioned before, while on jack stands the passenger side turns but not the drivers side, I even got it up to 60mph and never any movement from drivers side,

so locker must not be working for some reason.

Not necessarily. The G80 only locks up to a certain road-speed - and that speed is way lower than 60mph.
Replicate what I did to check if it is working.

 

[pressureangle]

Not necessarily. The G80 only locks up to a certain road-speed - and that speed is way lower than 60mph.
Replicate what I did to check if it is working.

Yeah, that's part of the G80 weirdness. The fast-moving governor locks the clutches, the big wing thingy disconnects everything above a certain speed. So essentially it's a low-speed-only locker. If you put it on stands and it gets to 20mph without engaging the other side, you have an internal problem. Hopefully it's only worn out, not disassembling itself. Still, the sticky axle is worrysome and with low fluid, bearings are still suspect.

 

[Pinger]

Out of curiosity, what do have in the way of endplay on the half-shafts as measured at the wheels?

The above was never answered - and is a potential indicator of level of clutch wear in a G80.

 

[Tnman54]

The above was never answered - and is a potential indicator of level of clutch wear in a G80.

axle shaft end play is around 1/16" on both sides

 

[Pinger]

axle shaft end play is around 1/16" on both sides

I have 0.9mm ( a smidge greater than 1/32'') on passenger side, none on driver side. A new cross-pin and C clips didn't eradicate it.
Yours has more wear somewhere. Maybe a new cross-pin and C clips would eliminate it, maybe it is clutch wear. It doesn't strike me though as clutch wear at a level to cause concern. What is of concern (in case you are unfamiliar with it) is the axle play reaching a level where the C clips can drop out. That though requires movement the thickness of a C clip (circa 4-5mm).