Rear End Locking?

[Big T]

I've put about 12K miles on my '99 since I bought it in January. From the outset, on slow turns from a stop the rear end behaves like it's locked. A little jumpy as if the vehicle itself is in 4wd, though not that severe. What could be the problem?

 

[trouttrooper]

Does it have the G80? It will be listed in the glovebox codes if you don't know for sure.

 

[Heartbeat Hauler]

I've put about 12K miles on my '99 since I bought it in January. From the outset, on slow turns from a stop the rear end behaves like it's locked. A little jumpy as if the vehicle itself is in 4wd, though not that severe. What could be the problem?

If it were me, I would start with a rear differential service, removing the cover, draining gear oil, replace gasket and install cover, then fill with the proper gear oil and additive. There is a better than even chance this will alleviate the problem.

Unless you have service records it's hard to say when it was last serviced.

OnEdit: As Trouttrooper posted, verifying that you do have the G80 is a good idea. If you don't the additive is not needed.

 

[btfarm]

G80 would have a drain plug on the bottom and a fill plug in the back cover. A posi unit would have the fill/level plug on the RH side IIRC.

 

[Big T]

I checked the code label in the glove box and there is a G80 listed amongst all the codes.

 

[btfarm]

Change it to a good quality synthetic 75w90 gear lube. No additives. You ight try Amsoil Severe Gear from Wrecker (one of our vendors).

 

[Ed HD]

:stupid:

The G80 diff is not a cone or clutch style diff, no additives should be used. You'll be best off doing both diffs and the TC at the same time. Amsoil's site has the fluid specifications as well as how much to add.

 

[THEFERMANATOR]

G80 would have a drain plug on the bottom and a fill plug in the back cover. A posi unit would have the fill/level plug on the RH side IIRC.

This applies to the 11.5" rear axle, the 10.5" one like the 6.5 uses doesn't have a drain plug. Pull the cover and see if there is any metal chunks inside. The G80 in the 10.5" is known to break the cross shaft that locks the spiders in and stay locked up or not lock at all. Mine did this though back when I first got it, and one day unlocked and has worked correctly ever since.