Postraction noise

[wes edwards]

Hello everyone,

I am restoring a 1978 pace car. The car was parked at least 3 years if not more. I think I have a problem with the positraction.

The car ran well until it warmed up and then a very loud banging noise statred in the rear end. The rear end fluid and positraction additive were replaced and the problem got 90% better.

Now it has a slight "knock" from the rear whther the car is warm or not when accelerating from a stop while the wheels are turned.

Thoughts?

[Scott Butville]

Re: Postraction noise

Sometimes it takes a while to work the oil into the posi-plates. Go do some figure 8's in a parking lot for 10 minutes. If that doesn't do it,add another tube of additive and repeat the figure 8's. If it's still noisy, you may have another problem, but most likely it's the posi.

[Gary R.]

Re: Postraction noise

Sounds like posi hammer. Most times the GM aditive will work- use 2 bottles.
Some info for you. The clutches in your 78 are not very strong,in fact they break very easily. Many times I rebuild a posi and the owner didn't even know there were several broken clutches in there. The current fiber clutches are total junk too if you have any real horsepower. I had a new set smudge in my fingers. If you have to open the differential then learn as much as you can about it. I have several posts about this running on various forums if you need any help let me know, I can tell you how to build a stronger then stock setup that will outlive and out perform the stock units every day of the week.