Hello. This may be me being a little paranoid but it seems to me that my posi on my drivers side is not working as well as it should. I go through some pretty rough/wet trails and I noticed after backing up (turning around) and going to go ahead in some sand that my passenger side wheel would spin and my drivers side would just make a moderate grinding/rubbing sound but no wheel spin. It almost seems like its trying to grab but wont quite do it.


Other times I can be on a straightaway (on sandy trails) and nail it and it will take off and spin. I dont know if its spinning as fast as the passenger side though(I cant stick my head out that window) :o)


I havnt noticed this until just the last week or so. And the grinding noise is what caught my attention, not the non spin issue...I can still just put it into 4WD and take right off.


Is this normal or do I need to have something checked out?


thanks,


Jason

I would start by checking/changing your rear end fluid. If the oil breaks down, it could effect the operation of the limited slip.

These Diffs are lockers, I think and as such operate slightly different than posi units. One of the differences is these type of lockers engage after the opposite wheel has been spinning whereas posi units try to prevent the opposite wheel from spinning to begin with. The advantage of a locker is they will allow a higher torque split between the two wheels and during normal driving you have an open diff. Either way they shouldn't grind.

Eric, I had the rear diff fluid changed just a couple of months ago. I had done it a couple months before that, but had a small gasket leak and then had my mechanic redo it when he replaced a seal in my front diff. I know he put mobil synthetic oil in it and no limited slip additive. Could that be the problem?


A64pilot, I wouldnt call it a grind necessarily, but a definate slipping noise. Kind of like when you'd have sand/mud in your brakes and you were doing a gentle brake. Not a squeal though either..


Are you guys saying that it should not silp at all under light-mod acceleration in sand? I think before in this same spot both wheels would spin but kind of wheel hop. Now just the pass. side spins.


Thanks so far,


Jason

Eric is the professional GM mech and I'm not. All I was wanting to point out is that in order for the locker to work there must first be wheel spin, unlike a posi or limited slip unit, but in my untrained way what your describing sounds expensive, like excessively worn clutches?

I gotta go with A64 on this.. that kind of noise is not good. I would start by pulling the rear cover and checking things out.

These Diffs are lockers, I think and as such operate slightly different than posi units. One of the differences is these type of lockers engage after the opposite wheel has been spinning whereas posi units try to prevent the opposite wheel from spinning to begin with. The advantage of a locker is they will allow a higher torque split between the two wheels and during normal driving you have an open diff. Either way they shouldn't grind.




They are not lockers per say. (lockers engage with gear teeth or dog clutchs not clutch plates) GM used the Gov Loc eaton in rear end until very recently and I belives they have switched over to a true LSD now. The Gov Loc is not known for sturdiness and will not fuction above 20mph or so. It will also not engage clutches until there is about a 100 RPM difference between axle shafts. If it is making noise, it is doubtful that a fluid change will fix it but it might help if wrong fluid is in it now.