Stupid Posi-Traction Question?

My 79 is the first car I've owned with a Posi-traction rear end. The previous owner said it was rebuilt about 5,000 miles ago. My question is it normal when making sharp corners at low speeds to experience the sensation like your driving on oval tires? I was told this was normal because the wheels are trying to turn at the same speed. This makes sense but I want to know that it is nothing to be alarmed about. Thanks in advance.

GM makes a positraction additive that can help that.


Dave

You can also get it at NAPA, and others. Add 4 oz to the diff fluid.

I have found when rebuilding rear ends that you need to change the gear oil after about 5000 and add new lube..

I had a vette that I rebuilt the rear end and added additive.. after about 5k miles it started sticking.. added more additive.. helped for a little while.. but not very long. it was especially bad on hot days. I drilled and tapped a drain plug in my diff.. (many rear-end shops do this as SOP, so you may want to see it is already has one) drained the oil.. added new oil and additive and never had another problem.

if you dont want to add a plug (strict restoration, etc.) use a suction pump to suck the oil out (what i did on my restoration vette) then add fresh gear oil and additive. btw try not to spill any of that additive.. it smells very bad and its persistent..

if you do want to tap a plug, ive seen quite a few places selling a kit that makes it idiot proof..

after you get the new oil and additive put in.. take your car to a large empty parking lot and do a couple of figure eights in reverse. then a couple in a forward gear

Interesting. So the impression I'm getting is that it shouldn't be "sticking" for lack of a better term. I think I'll try changing the fluid/additive and see what happens. Thanks for all the advice. It isn't making any noises or "clunking", it just the slow sharp turns that creates the 'out of round' sensation.

yeah i dont know what the correct term is..

but when you make a turn the outside wheel turns faster than the inside wheel.

there are clutches in the rear end to make a wheel slip..

this is why its called limited slip positraction. this way your rear end doenst drag the outside tire by making it turn the same speed as the inside tire..

if your clutches arent slipping, its because the additive is worn out.. common for a new rear end.. adding more doesnt help much... only replacing all the oil and additive.

generally they dont stop slipping all together, they just stick longer than they should and this slight hesitation is what gives you the feeling that your rear end is "sticking"...

Completely concur. When I bought the Black Goddess she was actually clunking around every turn. I changed the rear diff fluid and put posi lube from autozone in and it went away. Little did I know that was the least of my problems. But that's another story.....