simonjrwinter Posted June 5, 2006 Report Share Posted June 5, 2006 Got a bit of a clunk coming from the rear of the car when going over rough roads. I'm pretty sure I've ruled out the exhaust on all but the very roughest roads. I stood behind the car today and pushed it up and down on the rear end and there is a definite "clunk" coming from underneath somewhere. I'm not asking for diagnosis, as I've not even jacked it up or taken the wheels off yet, just some ideas as to what I should be looking for when I do get the time to look. Many thanks Simon Quote Link to post Share on other sites
F69 Posted June 5, 2006 Report Share Posted June 5, 2006 Simon, clonking from the rear can be a heartbreaker to sort out and is usually a process of elimination. I had a similar problem on my 6 and eventually solved it by replacing the metallastic bushes on the trailing arms with new poly bushes,and just to be sure I also replaced the rear spring donuts with poly ones and touch wood not even a squeak now. I wish you luck in your quest. The feeling when its sorted is great. Quote Link to post Share on other sites
Richard Crawley Posted June 5, 2006 Report Share Posted June 5, 2006 Simon I think the clue is it does it when you push on the suspension so it could be anything connected with that; if you’re still running lever arm shocks check the mounting bolts & the links; trailing arm bushes; loose drive train bolts or could be diff mounting rubbers/ pins. Quote Link to post Share on other sites
rob wilsher Posted June 5, 2006 Report Share Posted June 5, 2006 Simon, What about the diff mountings themselves. Have they been previously reinforced (boxed in) I had this job done in the 80s with body in situ on chassis. A telling sign can be differing vertical measurements between tyre circumference and wheel arch on rear wing. good luck Rob Quote Link to post Share on other sites
Andrew Smith Posted June 5, 2006 Report Share Posted June 5, 2006 A telling sign can be differing vertical measurements between tyre circumference and wheel arch on rear wing. Simon Another telltale sign is a clonk when the diff engages when pulling away from traffic lights or rolling the throttle on/off at low speed - 9/10 times this points to the diff mounts. Cheers Andrew Quote Link to post Share on other sites
jean Posted June 5, 2006 Report Share Posted June 5, 2006 Don't overlook the halfshafts, if the splines stick they will produce this clonk when the back of the car moves in a vertical plan. Maybe the time has come to clean and lubricate the splines Jean Quote Link to post Share on other sites
Guest ron Posted June 5, 2006 Report Share Posted June 5, 2006 (edited) SimonI think the clue is it does it when you push on the suspension so it could be anything connected with that; if you’re still running lever arm shocks check the mounting bolts & the links; trailing arm bushes; loose drive train bolts or could be diff mounting rubbers/ pins. I also think the clue's in the fact that it's there when you bounce it, check what Richard suggests, the diff and driveshafts don't normally clunk when you push down on the suspension. Ron Edited June 5, 2006 by ron Quote Link to post Share on other sites
Goswell Posted June 6, 2006 Report Share Posted June 6, 2006 Had the same problem which simply turned out to be the lever arm shocks mounting bolts , being loose, as already mentioned. It really sounded more serious and has just returned, after 10,000 miles, despite having changed to vertical shocks. Same bolts used in both cases, need more locktight. Quote Link to post Share on other sites
simonjrwinter Posted June 6, 2006 Author Report Share Posted June 6, 2006 Well, Had root round today. rear 1/4 bumper loose slightly, but sadly NOT the cause of the clonk. When going over bumpy roads etc it sounds like it should ALMOST be the exhaust. But it's not. Exhaust nice and tight, nowhere too near anything and no witness marks anywhere (also not QUITE the right noise) The chassis on the car is a replacement jobbie with strengthened diff mountings. Had the wheels off, and to my untrained eye, everything seems fine. Checked the lever arms, all seems ok. Guess I need a more trained opinion. Can anyone recommend a garage in the Essex/London area experienced with these things who would be able to offer some advice? Thanks Simon Quote Link to post Share on other sites
Guest ron Posted June 6, 2006 Report Share Posted June 6, 2006 (edited) Simon Before you do that check the shock absorber mounting bolts to the chassis are TIGHT even a very slight amount of movement there produces serious clunks when you go over a bump, this applies to original lever arm shockers and it's even more likely with the conversion plate for telescopics, I'm actually getting to the stage where I'm thinking of tack welding the plates to the chassis cause I tighten the bolts till my eyes pop out and a few thousand miles later I've got to do it again. Ron Edited June 6, 2006 by ron Quote Link to post Share on other sites
Richard Crawley Posted June 6, 2006 Report Share Posted June 6, 2006 Checked the lever arms, all seems ok. Did you have good look at the virtical links, if the rubber bushing is shot they will clunk! Quote Link to post Share on other sites
jonlar Posted June 6, 2006 Report Share Posted June 6, 2006 it's even more likely with the conversion plate for telescopics, I'm actually getting to the stage where I'm thinking of tack welding the plates to the chassis cause I tighten the bolts till my eyes pop out and a few thousand miles later I've got to do it again. Hi Ron, are the bolts stretching/slackening off - any wear showing on plates - have you tried using Loctite on them? Quote Link to post Share on other sites
jerrytr5 Posted June 7, 2006 Report Share Posted June 7, 2006 I'm actually getting to the stage where I'm thinking of tack welding the plates to the chassis cause I tighten the bolts till my eyes pop out and a few thousand miles later I've got to do it again. I had this problem with lever arms. Fit a longer bolt and stick a nyloc on the end so it's effectively double-nutted. If you convert to telescopics get the conversion brackets with the additional 'leg' that bolts on to where the bump rubber fits to the chassis. This eliminates the problem. CTM use this design, probably some others too. Quote Link to post Share on other sites
Guest ron Posted June 7, 2006 Report Share Posted June 7, 2006 (edited) 'Fit a longer bolt and stick a nyloc on the end so it's effectively double-nutted. If you convert to telescopics get the conversion brackets with the additional 'leg' that bolts on to where the bump rubber fits to the chassis. This eliminates the problem. CTM use this design, probably some others too.' Jerry Unfortunately I've got the three leg type, I think it's probably the bolts stretching as Jon suggested, I'll order four longer bolts from Namrick and put Nylocs on as you suggest, welding's maybe a bit drastic Ron Edited June 7, 2006 by ron Quote Link to post Share on other sites
jonlar Posted June 7, 2006 Report Share Posted June 7, 2006 Hi Ron, my Christmas prezzie a couple back was the CTM tele conversion, still not fitted, too busy trying to keep our everyday cars on the road. When I ordered (Angie wouldn't do it, in case she didn't get the right bits) I ordered an unpainte set, so I could have the option of welding permanently, if I wanted. Colin said they'd stopped powder coating anyway as it came off. Perhaps the best way is to bolt up and weld as well - belts and braces etc., it's not very clever if they're starting to move at all! Quote Link to post Share on other sites
simonjrwinter Posted June 7, 2006 Author Report Share Posted June 7, 2006 Solved!!! Despite my being SURE that the lever arm dampers were tight.....the L/H one was slightly loose. Tightened up with loctite (soon to be replaced with a damper conversion) Thanks again for all your help guys Simon Quote Link to post Share on other sites
Guest ron Posted June 8, 2006 Report Share Posted June 8, 2006 (edited) Simon, Probably a coincidence, but it's always the LH side that I have problems with as well?? Jon I suppose welding isn't a bad idea, I don't think there's any reason to want to take the brackets back off, I'll put it on the list of winter jobs and do it properly. Ron Edited June 8, 2006 by ron Quote Link to post Share on other sites
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