"POSI-TRACTION questions??

[Vettepilot]

1994 GMC K1500 5.7 w/auto trans. We are in the process of fixing it up and haven't driven it much.

It is supposed to have "Posi-traction" according to the option list. However, I happened to have the back end jacked up today, and when I turned one back wheel, the other one turned BACKWARDS like a vehicle with an open rear end. Puzzled, I jacked up only one side, and fired it up and put it in gear. It wanted to turn both tires, spinning the one in the air, and because it was in dirt/gravel, it turned the one on the ground on the other side too.

Now I'm REALLY confused. Will a worn out Posi do this; turn the wheels in opposite directions by hand, but try to go Posi under power??

Rebuild it?? Replace it?? I must have Posi...

Thanks!

Vettepilot

 

[454cid]

G80 is only positraction in cars, not trucks. Your truck got a locker that's normally unlocked. When the wheel speed difference is something like 100rpm it locks.

 

[evilunclegrimace]

Check your RPO list in the glove box and see if you have G80 listed. If so you have a locking differential and it needs a 200 rpm speed difference between the wheels before it will lock. It will stay locked until approximately 20 mph and then the governer will cause it to unlock and behave like an open differential.

 

[DerekTheGreat]

Yep. If you spin the one wheel fast enough, you can trigger the lock mechanism yourself. Getting one to lock will make you feel like you're ten years old all over again.

 

[DerekTheGreat]

1994 GMC K1500 5.7 w/auto trans. We are in the process of fixing it up and haven't driven it much.

It is supposed to have "Posi-traction" according to the option list. However, I happened to have the back end jacked up today, and when I turned one back wheel, the other one turned BACKWARDS like a vehicle with an open rear end. Puzzled, I jacked up only one side, and fired it up and put it in gear. It wanted to turn both tires, spinning the one in the air, and because it was in dirt/gravel, it turned the one on the ground on the other side too...

That was really dangerous and stupid, could've gone real bad in a hurry.. Right along the lines of, "I know just enough to F--- S--- up!"

 

[grampadirt]

This is how I tested mine after replacing a bad G80

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[Vettepilot]

Wow. Great info and great news! Thanks guys!!

BTW, the way I rigged up my test, it was safe. No "Safety Cops" were injured in the performance of this test.

;~)

Thanks again!
Vettepilot