Technical Noise form n/s/r

[swallowflies]

Hi there

Hope you enthusiasts out there can help.

88 Gran Finale. loud thumping noise coming from n/s/r even at low speeds, possibly suspension?
Have had on ramp. No play in suspension or bearings. checked exhaust mountings ok. shock absorbers seem ok. It really is quite loud and worrying. Happens particularly over holes in road or bumps.

Also indicators stop working when turn headlights on ( with engine running or without) battery is new and all other electrics seem ok. alternator charging ok. could it be the flasher unit?

Thanks very much

 

[jimbro1000]

Are we talking a "thump" or a "clunk"? it makes a difference....

If it is a thump then it is almost definitely a bush.

A clunk is more likely to be something out of place or a weak engine mount.

 

[swallowflies]

Hi

Yes a thump, very loud it jars the n/s/r end. Which bush could be causing the problem do you think,the rear control arm bushes?

Thanks

 

[jimbro1000]

It is most likely the inner bushes rather than the control arm but you need to get all of them checked. Most likely you will have to replace the arm.

Keep in mind that this is not a 10 minute operation and needs a lot of care and attention to detail.

The rear arm is "shimmed" for precise location, when removing the arm it is absolutely critical that you count how many shims are either side of each bush and put them back the same when refitting.

The electrics is almost definitely a bad earth but it will take some finding. The first port of call would be the earth "crown" rings in the front wings, they were never brilliant to start with and it doesn't take much to cause a problem. Just carefully remove each earth connection and clean everything up before refitting. If that doesn't make a difference check the column switch as these are basically the only two points where the wiring comes close to being shared (other than the fusebox and you would have popping fuses rather than just lights going out.

 

[swallowflies]

Thanks very much for the reply. I have had the bushes/arms checked and the mechanic cannot feel any obvious play in them at all. Could it just be starting to wear, yet still produce that loud thumping noise? Strangely it can thump over a small bump yet often over a big bump/speed bump it doesn't.
I will check the earth contacts as you suggest

Cheers

 

[jimbro1000]

Normally if the bushes are gone they really are gone and they is a fair bit of play. If the arm is proving solid then I suggest checking the suspension top mount. These do wear out as well, it isn't so obvious on the rear dampers but on the front it can make a big difference to the steering.

 

[swallowflies]

Hi

Today we have checked the top suspension mounts which seem fine. Three mechanics have been out in the car and all seem to agree it is coming from the n/s/r.
However, the only possibility might be that the rear track rod ends are very tight and difficult to swivel but we doubt if that would cause a loud thumping noise. When static, we can jump up and down on the rear of the car and cannot hear any particular out of the ordinary noises. The exhaust is tight and does not rattle and the engine mounts seem tight. Very bizarre!

Thanks so far

 

[jimbro1000]

Is the end of the gearbox slightly shiny (polished). This doesn't apply to the original 4-speed but the later 5-speed is longer and required a change to the chassis rail on that side and the swing arm. If it is clean and shiny (assuming you haven't cleaned it yourself) then it may be that something is rubbing or hitting it.

Sorry for soundling like clutching at straws but without being there to look it is hard to narrow the likely culprits down.

The rear control arms don't need to pivot except in the transverse plane to accomodate the movement of the hub up and down, as a result they tend to quickly become stiff anyway unlike the front which tends to become sloppy unless the car has been stood for a long time.

 

[swallowflies]

Hi again

Really grateful for the help so far. No, the gearbox is the same muddy colour all over!
After much discussion, the general feeling is that it might be the shock absorber. Although perhaps fine when over big bumps, it might be thumping/rattling when over small uneven bumps; although we are starting to clutch at straws and replace. Have checked all bushes/joints/bearings etc and all seems in order( as previous posts). So, persevering and trying to find rear shock absorbers-another nightmare. Any ideas?. Have trawled the net and rung at least 7 companies-nobody stocks them.
Sorry to labour this, but it is great little car apart from the aforemetioned problems.

p.s the strange ignition problem suddenly corrected itself. I turned the ignition switch on and off repeatedly ( more in annoyance than anything else!) and suddenly everything came back on. I would presume it is the ignition switch ( I was just about to take it out of the loop and run a tester direct) I will probably do that anyway when this other problem is resolved. Leave well alone!

Many thanks

 

[jimbro1000]

The most reliable supply of dampers seems to be KYB, eurosport claim to stock them in the uk.