need help crazy rear tire wear

**crazyforgms** · 01-07-2009, 07:47 AM

have a 98 Ls1 auto stock firebird.Two year ago I replaced the rear end with a stock low mileage 3:42 rear end.After doing that my car seams to eat tires for lunch.Rear tire only last 5 months on the back of my car.I didn't do brake stands of smoke the tires.I try using two types of tires of the on the back of the car I used kumhos,general tires the both didn't last?The rear tire seamed to ware even but didnt last.I replaced the pan hard rod with a non adjustable hot parts tubular pan hard rod.After I did that sometimes at high speeds the car seams to rock from side to side.Is the car just out of alignment or something else?Could the posi unit be lock all the time if so do I will add more rear end additive please help.

Happy Motoring Kenny

**mpfranks** · 01-07-2009, 08:06 AM

Originally Posted by crazyforgms

have a 98 Ls1 auto stock firebird.Two year ago I replaced the rear end with a stock low mileage 3:42 rear end.After doing that my car seams to eat tires for lunch.Rear tire only last 5 months on the back of my car.I didn't do brake stands of smoke the tires.I try using two types of tires of the on the back of the car I used kumhos,general tires the both didn't last?The rear tire seamed to ware even but didnt last.I replaced the pan hard rod with a non adjustable hot parts tubular pan hard rod.After I did that sometimes at high speeds the car seams to rock from side to side.Is the car just out of alignment or something else?Could the posi unit be lock all the time if so do I will add more rear end additive please help.

Happy Motoring Kenny

are you getting even tire wear, edge wear, or just not a lot of miles?

**Lucky 13** · 01-07-2009, 09:02 AM

sounds like the posi is stuck

**Richy_Rich67** · 01-07-2009, 09:48 AM

Posi is going to be solid a limited slip now thats different

**JoshieDoom** · 01-07-2009, 10:35 AM

Originally Posted by Richy_Rich67

Posi is going to be solid a limited slip now thats different

Posi is GM's trademark for their limited slip rear end.

Kind of like BandAid for an adhesive bandage or Qtip for cotton swab.
http://en.wikipedia.org/wiki/Limited_slip_differential

Take it to an aligment shop. They can see whats going on.

If it is in spec, I would see whats going on inside the rear end, it might be that your clutches have locked up and keeping the rear end locked. If you take a corner does the back end chirp any or jerk side to side?

**crazyforgms** · 01-08-2009, 12:04 PM

The tires on the back seam to were even the just were out quick.if I remember right when I make a Sharp turn the car seam to jerk.When I installed the rear end I only put synthetic differential fluid in it no posi addvive could be the problem?.

Happy Motoring kenny

**JoshieDoom** · 01-08-2009, 12:13 PM

Very Possible the clutches have stuck. Pop off the lid. Clean everything well and put the correct fluid with a bottle of Limited Slip Additive. Should cure/help it

**crazyforgms** · 01-08-2009, 12:35 PM

Thanks guys I will try that when it gets better weather

**JAGUAR5822** · 02-02-2009, 10:12 AM

Keep in mind to only use additive on the Auburn units. If you have a Zexel-Torsen, you don't need it.

**cant.b.caught.z28** · 02-02-2009, 10:45 AM

does it hurt to use the additive with a torsen carrier?

**JAGUAR5822** · 02-02-2009, 10:47 AM

I don't remember if it causes any adverse effects, you'll have to search around for that one.

**JoshieDoom** · 02-02-2009, 01:44 PM

Originally Posted by cant.b.caught.z28

does it hurt to use the additive with a torsen carrier?

There will be no harmful affects.

**Eugenio_SS** · 02-03-2009, 08:52 AM

Originally Posted by cant.b.caught.z28

does it hurt to use the additive with a torsen carrier?

no...

**bigrondownhiller** · 02-03-2009, 12:41 PM

What are the numbers on the side of the tires you have now? Treadwear, temp, and traction?

**RedVertTA** · 02-08-2009, 12:03 AM

Could be alignment, I had that for awhile and alignment corrected it.

**Too Fast** · 02-08-2009, 03:25 AM

Did you notice your steering wheel was crooked after the rear diff install? If you did, it is probably not in the car straight, causing your car to dog-track, which would scrub the rear tires just going down the road. You need to take it to an alignment shop to see if one side is too far positive with the toe reading and the other side too far negative. Talking about the rear toe, of course. If so, your differential needs to be centered better and that will help the tire wear.