Drive Shaft: Rear end/Drive shaft "clang"

[karterfred88]

This is on my 63 Avanti, before I start ripping the entire driveline apart, maybe some others have had this noise and know where to start. When backing up or moving forward from a rest and attempting to go over a small bump, as into my garage, when I give it enough gas to "bounce" past it I get a "clang" or loud ringing sound from the drive line. I thought maybe it was the universal binding from excessive pinion angle, but it occurs going forward or backward, always when putting an extra strain to get moving. There seems to be a lot of lash in the rear end, noticed especially when putting it into gear from reverse to drive. All the mounts are new. I thought maybe the rear linings were hanging in the drums and "popping" loose but the seem fine and sounds of a ringing drive shaft shouldn't be transferred from the brakes anyway. Any ideas.

[studegary]

My guess is within a universal joint, probably bad bearings.
Do you have a pinion angle/driveshaft angle that is not stock? This can cause universal joint problems in forward and/or reverse.

[karterfred88]

My guess is within a universal joint, probably bad bearings.
Do you have a pinion angle/driveshaft angle that is not stock? This can cause universal joint problems in forward and/or reverse.

By "not stock" I assume you mean not as per the Stude manual. Both front and rear springs seem to be excessively sagging but no modifications made. As the rear traction bars (Torsion Bars) are there and they position the rear ends pinion angle, I have to assume it's close. I like the idea of pulling the rear universal as it is the easiest. I've yet to drive this car over 20 MPH as it has had issues with the brakes, steering and wiring. If I had been able to get it up to a decent speed I might have been able to feel it.

[Bud]

Have you checked axle nut torque as I've heard a loose rear drum make a noise like a bad U joint. Bud

[Tom Bredehoft]

Try bud's idea, look at the nut on the end of the axle, look for bright orange rust under it. If there's rust showing, that indicates movement, which should not be there. Take the brake drum/hub assembly off, clean inside and out (shaft and cavity) until shiny, do NOT lubricate it, and reassemble, being sure that the key goes in last, with the bevel toward the axle. Tighten to 170 ft lbs, then tighten until the cotter pin will go through.

[JoeHall]

What Bud said. It may well be the source of the noise, and at the very least its a good place to start, and its free & easy to check.

[Deaf Mute]

What "Tom B" said.. I did find "key slop" on my Avanti on the left side. I checked out a new key on the axle (tight fit) and in the hub (loose). I purchased a new hub, got that all tightened down, checked the right one & it appears OK...
I still have the "clunk" when first accelerating forward... or backward. Pinion has been checked (I do not have Twin Traction), U-joints have been replaced as well. The transmission was rebuilt last year as well.
I don't know what to try next... so I just drive it, living with a "clunk" when changing directions.

[JoeHall]

What "Tom B" said.. I did find "key slop" on my Avanti on the left side. I checked out a new key on the axle (tight fit) and in the hub (loose). I purchased a new hub, got that all tightened down, checked the right one & it appears OK...
I still have the "clunk" when first accelerating forward... or backward. Pinion has been checked (I do not have Twin Traction), U-joints have been replaced as well. The transmission was rebuilt last year as well.
I don't know what to try next... so I just drive it, living with a "clunk" when changing directions.

Even if it is already at 170 ft lbs or so, draw the axle nut down another 1/6th turn, at the next window for the cotter pin.