[budsthe3]

The last time I used my Chevelle and did a burnout, the rear drivers side did not make a mark on the street. But when the car is on jack stands and I spin the rear wheels they move in the same direction like a posi should.
If the wheels still spin in the same direction can the posi still be worn out?

 

[pannetron]

Yes, sounds like the clutches are worm out. If you replace the diff, I recommend a TrueTrac helical gear diff.

 

[200170]

Have someone hold the other wheel and see how much power it takes to stop it if possible. As you are aware there are clutches (mine are carbon fiber) and there are spring packs (mine are 400 lbs) but stock are usually around 200lbs. So yes it can wear out the clutches like any other clutched device.

 

[budsthe3]

Darn, I didn't even put this posi in too long before it started to fail

 

[lookback]

When I did run a posi, dry burouts do wear clutches. You can purchase shims that go where clutches are, to tighten up clutch pack in carrier. Don't have to remove the posi case, to tighten up the clutch pack more difficult but doable. Randy ring and pinion would have the parts needed. When I set up posi units I use no springs and no spring plates. Set it up nice and tight with the shims between carrier and posi clutches where you can barley get in spider gears. Springs preload and cause early wear on the clutches. You may not need clutches take them out and look at them see if you can see or feel or see little squares on plates, solid clutches are best if yours are to worn. If you can find the 22 plate posi clutch set for the 12 bolt they set up much tighter with the right amount of shims on both sides. They last longer to.

 

[Kirk's67SS]

Darn, I didn't even put this posi in too long before it started to fail

I had my 12 Bolt Posi Rebuilt with a New Rebuild Kit / Springs Shims etc.
a year later it was back to a Peg Leg again
bought a New S60 with the TrueTrac Helical (worm like) Gears
7 + Years of Hard Street / Hwy Driving and lots of Track time with NO problems

 

[Alwhite00]

OP, what brand posi? OEM?

 

[budsthe3]

OP, what brand posi? OEM?

OEM

 

[Bob Tiley]

Since it is OEM you just need to replace the clutches and check the springs. Not that hard but you will spend an afternoon and have to replace the oil and posi additive. Just keep all the shims accounted for and put them back where they came from. Did you rebuild it when you installed it?

 

[budsthe3]

Since it is OEM you just need to replace the clutches and check the springs. Not that hard but you will spend an afternoon and have to replace the oil and posi additive. Just keep all the shims accounted for and put them back where they came from. Did you rebuild it when you installed it?

It was actually originally an open diff but I put a brand new OEM style I bought from Jegs many years ago. I can't remember the brand name but definitely an OEM style

 

[200170]

Darn, I didn't even put this posi in too long before it started to fail

What type of differential posi fluid do you have. Many do not recommend synthetic. Remember posi is not a Detroit locker either and they will slip and it is possible that you will not see dual tracks in some situations. Especially if you didn't install aggressive springs and clutches. It may have still been pushing hard despite not spinning. Find out what is installed and if necessary install a dyno lube with additive and see how it is.. Some syn's are just too slippery and are not recommended with posi. . Some will even VOID your warranty using synthetic lube.

 

[big gear head]

There are different brands. If you used an Auburn then it's not hard to believe that it's already failing. The Auburn can not be rebuilt, shimmed or repaired in any way. If it's worn out then it's scrap metal. If you used an Eaton or Yukon then you can fix it.

 

[200170]

A little more abut springs, clutches and lubes.

FAQs | Eaton Posi | Differentials | Eaton

www.eaton.com

 

[big gear head]

Still need to know what brand it is. Nothing is going to help until we know what you used.