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TR6 Clunking noise in rear continuing

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pdplot

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I've posted this before but the problem is continuing. I thought it might be the plywood panel over the spare tire which did make a noise when I flexed it, but after stuffing a couple of old undershirts under it, the panel did not move but the loud clunk continued when I drove the car over a rough road. Here are the facts:
1. The noise only comes when driving over a rough road - including my driveway. It is not dependent on speed.
2. It is very loud. Sounds like a sharp "Clunk".
3. Unlike when I had a bent tube shock rod, bouncing the rear bumper up and down makes no noise at all. (Note - as I've posted, suspension travel is limited). The bent rod made a clunk every time the suspension moved up and down - not as loud - more of a loud click.
4. The shock bolts are tight.
5. Usual small TR6 clunk when letting out the clutch or backing up. Last time we checked, the diff mounts were fine. They had been weld reinforced when I bought the car.
6. Right trailing arm bushings were replaced when we put a new arm on there and hub was rebuilt by TRF.
7. Stainless steel exhaust system seems tight with all hangers in place. Single pipe system.
I will award a prize to the expert out there who can correctly diagnose the problem and tell me what must be done.
 
Even if diff mounts in the frame are solid, check the bushings. I had a bushing where the steel tube that goes through the rubber separated from the bushing and allowed the differential to move.
 
Have you checked the lug nuts to make sure they are tight? Also, the studs in the aluminum trailing arms are sometimes stripped. Check your rear wheels.
 
Other random things to check -
If you're running a rear sway bar, check the links. Worn sway bar links can cause a horrible clunking sound on rough pavement or when changing direction left/right.
It sounds like you're running a tube shock conversion, so shock links won't be an issue. But if you're running levers, worn shock links can have the same effect as bad sway bar links.
 
You might want to check for play in your u-joints; since you said there was a small clunk when going forward or backward. Does it do it when you are making a turn?
 
1. Car has wire wheels. They are tight - very tight.
2. I don't think this thing has anything to do with the driveline. Only hitting bumps.
I'll have to arrange to get the car on a lift. My days of crawling under are over, sad to say.
 
pd,

One unusual thing to check is the handbrake cables. They run over the top of the frame (diff mount part) and can move vertically and contact the underside of the body in the rear shelf area. I just took a picture looking forward from behind the pass rear wheel; you can see the cable forward of the shock. Push it up and down to see if it reproduces your sound. The cable doesn't have much mass, but the right bump might bounce it up and down a bit. The factory put a rubber casing over part of the cable to cushion it some. P1090379.jpg

Jeff
 
Have someone check for a crack in the frame, near your rear tube shock absorber mounts.
 
I don't think a handbrake cable would make such a loud knock. This is loud. Doesn't sound good. I'll have someone else drive the car and listen. Cracked frame? Maybe. I'd have to pull off a wheel to check, and that's a problem - I can't lift the heavy wheel and tire back on the hub any more - bad back and who knows what else. Would it show up on a lift with the suspension hanging down or would the wheel have to be jacked up to expose any crack since I only hear it going over bumps?
 
The likelihood of a cracked frame from the stress of a tube shock conversion is going to depend on which of the several versions of shock mounting kits you have, but the wheel will need to be removed in order to make n inspection....As for being on a lift if the car is lifted on it's frame rails with the wheels still on but just hanging down, I'm not sure what you'll be able to see.
 
I have the Roadster Factory kit - installed 4/12/2001. KYB shocks.
I'll try to check it myself and use the floor jack to lift the tire back on the hub. I don't really know what I'm looking for or where to find it. I assume around the upper mount. I will report my findings.
 
Follow up. I don't have a rear sway bar, but the noise is similar to one I had from a bad front sway bar bushing in my 1984 Audi Quattro, but that noise was when I turned the wheel and put stress on the bar.
 
Update. I tried to remove RR wheel to examine mounts but was unable to. The centerlock nut? whatever you call it - was too tight and actually bent my longer wrench when I stood on it and I was unable to hammer it loose with my short wrench so I jacked it up, shoved a jackstand underneath and crawled under with my miners light. From my limited view, everything looked fine. The diff rubber (poly?) bushings looked fine although I was unable to see what lay underneath and probably wouldn't be able too unless the diff was unbolted and dropped away. There was no obvious crack near the top shock mount. What I did see was the exhaust pipe actually resting against the frame where it went through and it looked pretty close as well further up- maybe close enough to hit when going over a bump. All clamps and hangers are tight. Question - does the exhaust pipe change position when hitting a bump or does it move as one with the frame? The noise does sound like it's coming under the rear of the passenger seat.
 
While under there on my new creeper, I tightened the rear brakes and examined the rest of the car. The only rust was on the right side rocker panel with one small hole. The entire frame and floors were solid and free from any rust. The front sway bar end bushings were shot and the tie rod rubber bushings looked a bit tired as well. I did notice a very small amount of play in the left rear wheel-maybe a few mms. Is this anything to worry about? The right hub was replaced a few years ago. No play at all.
 
Does anyone have any ideas how to get the spinner off so I can pull the wheel and look at the upper shock mount? Propane torch? That long lug wrench is a POS. It bends when I step on it and I'm not heavy enough to make any headway against the spinner. Hammering on the short wrench with the copper hammer with only one hand is not going to cut it. I just don't have the strength any more.
 
Don't hate me for asking, but are you hitting the spinner in the correct direction ?
 
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