OK so a few nights ago while leaving the hang out i launched with the drag radials on and a friend of mine said that i left one hell of a one legger down the street. He tells me my posi is going out. A few nights before i raced a few people and each time i had two solid black marks left by the drags. Last night i put on my street tires and took the car for a ride. 2-3 times i did a little launch and all the times there were two very distinct black marks.

what would have caused it do to a one legger and could my posi really be going out!!?? the car has about 110,000 miles on it.

 

either your posi goofed up that time or by sheer dumb luck your wheel ran over/thru something slick enough to cause it not to heat as quickly. (like a burnout without leaving the marks)

 

The factory posi in your 1997 Formula 10-bolt is the Auburn Clutch-Cone unit. And yes, with over 100K miles it "could" be worn out. And the OEM posi unit can't be rebuilt.

Auburn now makes a "Pro-Series" posi upgrade for the 10-bolts which comes with an 2-year exchange program I believe.

WD

 

Maybe when you launched on the DR's you turned the car slightly and that locked up one wheel (if your posi is going out). Easiest thing to do is to jack up the rear of the car, put the car in neutral, and spin one of the wheels. If the other wheel spins the same direction your posi is fine, if it goes the opposite direction your posi is shot.


If it does spin the opposite direction the car may still leave two black lines when you do a burnout or launch hard as long as you go perfectly straight, but if more pressure/weight gets applied to one wheel than the other the wheel with more pressure/weight being applied to it will lock up, leaving only one black line.

 

Thanks guys, I'm gonna undercoat my car today so i'll check some things to see if it is in fact going out.

 

both wheels turned the same way so im guessing its fine for now. thanks for the help!

 

Actually, you'll need someone to hold the wheel on one side stationary while you check the torque bias between both wheels. Basically, "by hand" and attempting to turn the wheel, you should not be able to overcome the pre-load (bias) between both wheels. Again, that is in neutral and parking brake off.

WD

 

sorry to jack this, but it's better than making a new thread.

engineer, are you saying that if a person holds one wheel, you should not be able to turn the other one by hand? I have a feeling mine is going out, both wheels spin the same direction while free, but if someone holds one in place I can easily spin the other wheel by hand.

is this thing gone?

 

Yes, you should not be able to turn the wheels separately. They should be somewhat locked together, or very hard to overcome by hand. The springs on the clutch-cones establish a pre-load, or bias (check-out the photo I posted above). Typically, I good posi unit will have enough pre-load in the clutch-cones that you won't be able to easily overcome that pre-load by hand. This is a standard shade-tree method of checking a posi unit.

WD

 

I wouldn't say you can't turn the but they should be pretty hard to turn


another thing to look for is if one tire spins backwards during burnouts.....that means its shot

 

hmm I can turn mineby hand pretty easily, but it will smoke both tires in a straight line.

However, Its tough trying to hang the rear out, I need to get someone to watch me do it but I'm thinking mine is well on it's way out. It also chatters sometimes when i pull out hard on right turns.

I'm planning on doing gears this summer and I'd hate to pay for differential work then lose the posi altogether..