PiSoft

[SOLVED! Solution in post #16]

Hi,
I have come to the point where I need some external input on this.
Soon after I bought this car ('56 reg DBW, 70K on the clock, everything is factory standard) it developed a noise from the rear suspension.
The noise only audible on road bumps or potholes. It is definitely a result of the compression or the rebound. It happens too quickly to decide which phase...

Very difficult to describe the noise itself. If you have ever heard a flatbed van loaded with some heavy sheet metal going over a bump, making the sheet metals slightly come apart and then fall on each other again, then this noise is similar to it. It is definitely coming from the rear suspension.

What I have observed so far:
- it comes on under slight acceleration, moderate acceleration (couldn't check hard accel), coasting with gear engaged, free rolling in neutral/clutch depressed.
- it does not seem to come on under braking
- sometimes it takes 5-10 bumps to start the noise after the car rested for longer period
- the noise comes on only on bump/pothole impact
- the handling of the car doesn't seem to be effected, normal road use only. I feel it well planted.

What I have checked and did so far: (none of these helped)
- The wheels are securely installed
- the spare wheel is secure :-)
- there is nothing loose in the boot
- I have re-torqued the hub nut as suggested by many in the forums. I believe that I was the first one doing this on the car.
- I have replaced drop links at the rear. I'm sure it is torqued down properly.
- I have replaced the rear strut with a pair from my previous car. Although they have around 130K in them they have never produced similar noise on my previous car. No leaks or obvious damage on them. They are from a '03 car, so a bit stiffer than the originals. The originals don't seem to be damaged but I haven't checked the rubber stopper yet.
- I put the car on stands and tried to find excessive play in the rear suspension. The suspension arms look secure, the wheel hubs look secure, Visually the diff mounts look good. I re-torqued the subframe bolts (they were not loose). I did not see any obvious failure of any of the bushings.

I have found a little play in the passenger side driveshaft though. It is little and only goes alongside of the shaft. I can pull it in an out to make a little noise. There does not seem to be rotational play though.
I have found a little play on the output of the diff. I can lift it up a little bit, something like 1-2mm. I don't know if it is normal/allowed.

I am in the South (Dorset) and trying to avoid going to the main dealer just now. Can you recommend somebody with really good reputation with our cars? I am very reluctant to just book my car into a random garage...

Maybe somebody is around who could have a listen to the noise?

I'd appreciate any input as I am getting a bit worried...

Many thanks,

Imre

noodels

Exhaust mountings
Rear Toe in, perhaps a little too much.

LEEF

Hi
I had a very similar annoying random clunk driving over bumps etc. I checked all you have done.
Anyway, following new suspension bushes, drop links, re-furbed brakes , hub nut drive cups re greased, etc,etc. the annoying clunk was occasionally still there
It ended up being the rear number plate brackets that were rotten. Being loose, the whole housing moved about as I drove over bumps etc. and the resulting clunk resonated through the body work. I made some new brackets and the clunk was gone.
It may well not be your problem but it solved mine.

GreenmanS2000

Auto Headlight adjuster?

PiSoft

I have checked the exhaust while I was under the car and it was fixed firmly. Tried shaking it but no noise.

I did not have a geometry checked and set yet, so toe in might be something

Thanks!

PiSoft

Wow!
I would not even have thought something like that! I will definitely check it out when I can! Such a shame that it's so windy these days... I can only work on the car outside...
I'll report back when I had a chance to check this!
Thanks!

PiSoft

This is one of my suspects haven't been checked. To be honest there is a play in the connecting rod's ball joints. What drove me away from it on the first place is that the noise sounds to be coming from 'a lot bigger mass of metal' than the headlight adjuster.
But it is easy to remove it and doesn't cost a penny! I definitely try it!

Thanks!

dls91

i had knocking coming from the rear. swapped the shocks from side to side and realised it was one of my coilovers. sent hem off to be overhauled. happy days!

GreenmanS2000

I was surprised how much noise something so small made

Fatbloke

One of my brake dust shield thingies was knocking against the calliper over big bumps, That made a lot more noise than it really should have too.

I bent it away by a couple of mm.

Might be worth checking.