noblejr

The Car: 1977 Chevrolet Corvette L82, automatic, posi rear end

The Problem:

I originally chalked this problem up to bad brakes, with the brake pad shifting around inside the caliper housing. Now that I have replaced all my leaky, worn out calipers and installed new brake pads, I still notice a problem.

What I originally though was happening is that one of the brake pads was gripping the disk, moving up out of place a little, then popping back down and releasing the disk. I would feel this happen a few times when I drove forward after backing up. Since I now have all new calipers and pads, I doubt this is what is really happening. What I feel when I'm driving very slow is a resistance and then feel a "klunk" and a release of the resistance. It will do this every few seconds until I speed up. I don't always notice this, but just occasionally when I'm driving forward rather slow.

Next week I'm going to check all my U joints (there's like 6 or 7 of them) and maybe jack up the rear and let the car run slowly in drive.

Anybody have experience with this problem or know how I should go about troubleshooting it?

stingc

Klunking sounds are often differentials. Does it make more noise when turning? Also check you parking brake.

Be careful with running the car in the air. Unless you have much stiffer springs than stock, the angles aren't good for the u-joints (stiff springs allow less droop).

I have a C3 too btw

CS733t

What about a possible torque convertor problem?

But yes it does sound like the diff is acting up.

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Peryn

How frequent is the sound? My guess would be torque converter, or differential, though im leanning towards the diff. I doubt u-joints are the problem. From your description, the noise doesn't happen very frequently at low speeds. Your driveshaft is spinning at 3-4 times faster than your tires, so even at low speeds, the noise would be pretty frequent. "every few seconds" sounds like a lot slower than you would get from a driveshaft. It sounds like once per revolution of the tires, and at those speeds your pretty much limited to a rear-end problem. take off the inspection plate sometime and take a look at it.

ooh, an idea. Put the car in neutral and then move it slowly and see what happens. See if it makes it at a stop, and see if it makes it when moving. In neutral, the TC will be spinning, without you moving. If it makes this noise, or a difference in rpm or something, its prolly the TC. If it doesn't make it till moving, then its somewhere either IN the tranny, or behind it at the diff.


I have something similar to that on my jeep, but nowhere near as intense. One of the bearing in the rearend is shot ( i cant remember...i think it was the side bearing in the diff). As i rotate the tires, resistance increases noticably at one point. Then all of a sudden it releases pressure and is fine till i rotate it around again. You could have a similar problem. Just a thought, i could be way off base.

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