rear end? - funny sound

[LanceB]

OK I think this sound is coming from my brothers rear end. When I am at a dead stop and I let off the brake without giving it gas and really just idle along, sometimes there is a "popping" or "clicking" sound. I don't know how to describe it or how to make it do it all of the time, but I almost picture one of those clocks you see in a grade school that clicks along. It stops as soon as I give it gas. It has done it since he has owned the car for five years. He had new gears installed and the guy that installed them said there was something with the rear end that wasn't exactly right and he had a hard time getting the gears installed and even finding the right gears to fit in it. This is the same guy that wrecked it so we had to go get it back, so I was never able to find out exactly what he was talking about. It did it with the old gears and the new ones. It is very strange, I don't know if it is anything to worry about since it has always done it, but I wish I knew what it was. At first I thought the brakes were catching, but after replacing, no luck. I thought transmission may be slipping, I changed filter and fluid, still the same.

[wishuwerehere82]

If it is coming from the rear end, it could be several things.
It could be the positraction clutches or the carrier bearings for the gear cluster.
That would be loose with no load on it, and stop under power.
If it was ring gear to pinion mis-adjustment, it would probably whine.

It could be U-joints on the half shafts.

Diagnosing a rear end noise is something that is hard to do without pulling parts off and checking them piece by piece.

[jims427400]

I had a similar clicking sound from my rear end.. turned out to be one of the pins that hold the emergency brake pads in place on my 67. It was bent, took it out,replaced w/ a straight and clicking was gone..
Good luck..

[pasvorto]

I had a bunch of weird sticking anf poppinh noises when I got mine. Once I removed the old differential fluid and replaced it with 2 units of posi fluid and the rest with "official" GM fluid, the npise went away. Turned out to be dry posi clutches.

[LanceB]

Thanks for the info guys. If I was a betting man I would go with the posi clutches, because it stops when I give it gas. I am going to siphon out old fluid and put some new in there. I would have thought this would have been done when the gears were replaced a year ago.

[bmotojoe]

Once you change the additive and fluid find a large enough parking lot and do several tight figure 8s turning right and then several doing them left. This should work the new fluid and additive into the clutch disks.
Brian

[Vette79]

I had the same problem and after removing the old fluid and replacing with new fluid and conditioner. Problem solved. Like Brian says, do some figured 8's to work in the new fluid. I also replaced the pinion seal as it was leaking pretty good.

[LanceB]

I haven't looked at my brothers 77 rear end (the problem rear end) yet as to where the drain/fill hole is, I am assuming it is like my 81 where is has a fill hole at the top side. From what I remember you fill it up to where it is about to come back out that hole. Do you think a siphon will the best way to get the old fluid out of there?

[LVMYVT76]

Its the only way I know of, short of pulling the diff out. Corvette fever showed how to drill and tap a drain plug in. I never thought it was needed since you ususally don't have to change this fluid that often.

[Vette79]

Originally Posted by LanceB

I haven't looked at my brothers 77 rear end (the problem rear end) yet as to where the drain/fill hole is, I am assuming it is like my 81 where is has a fill hole at the top side. From what I remember you fill it up to where it is about to come back out that hole. Do you think a siphon will the best way to get the old fluid out of there?

A siphon is what we used to remove the old fluid. Fill to the top of the hole.

[LanceB]

As always thanks for the help!