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knocking sound from rear end


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Hi everyone and thanks so much for past advice. Helped me no end.

I have vitesse mk1 2litre. There is a knocking sound seeming to come from nearside rear or middle of car. It is from just moving to about 20 mph when road surface is a bit poor. Going over bigger pot holes etc and it does not seem to make this noise. It sounds like something is loose, the sort of sound a loose exhaust hitting body/chassis might make. I have had rear end up on ramps a couple of times and there is nothing obviously loose that I can find. Nothing regarding suspension problems has been picked up on last 2 MOT's.

I have had car nearly 2 years. I first noticed it a couple of months after buying car, though I think it has got worse over time (2.000 miles).

Any suggestions as always much appreciated.

Cheers

Dave 

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Hi and thanks a lot for advice.

The exhaust seems pretty secure and spare wheel clamped down ok.

I would not class noise as rythmical. I'm pretty sure It occurs on slightly uneven road surfaces. On good road surface, no noise.

I wiil check the body bolts when I get a mo.

Cheers

Dave

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Hi. Have checked the two bolts on boot tunnel. They are tight. I assume they go into welded captive nuts on diff cross member?. Also rocked car up and down to try and simulate whats going on when driving as it makes noise at very low speeds (and up until about 20mph). Not sure what to do now. Hoping its not part of suspension and could break when driving at speed.

Cheers

Dave

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I had a clunking from the back of my Spitfire going over bumps sometimes, turned out to be the top leaf of the spring had broke in two and was slapping against the underside of bodywork.

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I have very recently discovered the cause of a similar knocking sound on my GT6.

 

Turned out to be the bottom leaf of the rear spring catching slightly on the clamp that wraps the leaves together on the left hand side, it is too tight and the leaf sticks and then pings and slaps the next leaf, I had to put the car over a pit and bounce it up and down for ages whilst taking it in turns to watch what was happening underneath. I haven't fixed it yet but I know it's not major problem now.

 

Henry

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Thanks for that info Henry. Looks like there are 4  clamps. Have looked at factory manual. Can't see info on adjustment. I assume it would be done with car not jacked up and therefore "when driving" load on spring. Any ideas on what I should be looking for with adjustment appreciated.

Cheers Dave 

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Yes, there are four clamps, the problem for me was the outer left one. There is no real adjustment you can do other than lever them open a bit with a screwdriver or something or squeeze them shut etc...

 

My one was just squeezed too tight around the spring and it was grabbing the lower leaf. We just stood bouncing the car up and down over a pit watching it. It's probably something completely different on your car but I thought I'd mention it just in case.

 

Henry

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  • 1 month later...

Hi chaps,

I'm getting a similar problem to Dave with my Spitfire 1500 but Pete Lewis makes a very good point above - it's not a rhythmical knocking sound for me, it's a random crunching/clattering sound which doesn't seem to be related to speed/particular gears/cornering/braking. Like Dave I expected to find something loose getting caught up in the drivetrain somewhere, like you would expect a bag of bolts going round and round one of the drive shafts to sound, but again there's nothing immediately obvious visually. Really baffled.

I've ruled out UJs, wheel bearings and prop shaft. The diff would be the obvious candidate but it's already been reconditioned (by a specialist firm) recently after becoming worn and producing the classic rhythmic knocking sound. The guy who reinstalled the diff (mechanic relation of mine) assures me that he doesn't believe this NEW noise is coming from there. But after poking around he is talking about checking the leaf spring first and seeing if anything stems from that, but I just can't see how a rotational sort of noise could be anything do do with the leaf spring or suspension...

Can anyone advise on the right course of action before I go on an expensive wild goose chase?! If anyone is near Eastbourne and thinks they might be able to lend an expert opinion, let me know! Or if anyone recommends a specialist near Eastbourne that could also be very helpful.

Cheers. Ben.

 

Is this rythmical or random

check the two body bolts which clamp down on the diff crossmember under the grommets on the boot
tunnel

rythmical would be drive shaft Uj endfloat

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