Knocking sound from the back of car - move off / slow down

[bigV8]

Starting to get a strange knocking sound when moving away slowing down, checked wheels, suspension, chassis and exhaust but no problems found - thoughts appreciated

[tubbystu]

Where is sound coming from ? Front (engine), mid-car (drive train), rear (axle) ?

Could be a drive shaft bearing at diff if its coming from under/just behind drivers seat ?

A bit of a stab in the dark without some more detail though.....

HTH

[bigV8]

Definately coming from the rear behind me - maybe more on the left hand side but difficult to track from drivers seat

[GreenV8S]

Loose diff mounting bolts or worn bushes?

[mep12345]

Mine used to do this (I assume from your description it is mainly as you slip in the clutch in first and reverse gears [worse I found in reverse], or as you dip the clutch and relieve power on stopping) and I stopped the majority by changing the off-side drive shaft CV joints. The noise finally stopped when I took the body off and replaced the U shaped Diff mount (which was persihed and split) I don't get the noise at all now.

BTW even with the diff mount split I couldn't really move it by hand so the only way you'll know if this is the case is to drop the diff or remove the petrol tank to be able to see it.

HTH

Mark

[Barkychoc]

The rear diff mount on the V8S is a bit different - but the same applies really.

If you come to a standstill then move in reverse does it clunk or anything as you take up the drive? Similarly stopping in reverse then going forwards.

It does sound like some play or something broken / loose in the drive train somewhere to me.

On the diff carrier bracket there are 2 rubber mountings on top of it that bolt it to the chassis - each one has a bolt that goes through it into the chassis. There are also 2 rubber bushes at the rear of the diff (different to V6) - my car overall was in very good condition when I stripped it - but those 2 rear bushes were absolutely shot allowing the diff to twist.

[Barkychoc]

Pic below of rear mount



Also check those black rubber mounts on top of the cradle

[GreenV8S]

Barkychoc said:

Pic of spangly clean chassis

I'm jealous!

[Barkychoc]

It could be a Haynes manual that bears no relation to reality!

[page3]

GreenV8S said:

Barkychoc said:

Pic of spangly clean chassis

I'm jealous!

If my S chassis was like that I don't think I'd bother putting the body back on.

Can't help with the clunk though...

[mep12345]

Barkychoc said:

The rear diff mount on the V8S is a bit different - but the same applies really.

Doh!!!!!! should have realised V8S from his name shouldn't I. I'll

[Barkychoc]

page3 said:

If my S chassis was like that I don't think I'd bother putting the body back on.

Well I've spoilt it now! The outriggers are black as I have coated them with some anti stone chip coating. I thought it was better to do it now while they are pristine rather than when they start getting chipped & rusty.

[steve j]

Check the C/V joints on the driveshafts and the U/J`s on the propshaft for wear.

[bigV8]

Thanks to all for your suggestions - will keep investigating

[V8Smith]

David, did you get to the bottom of this, what was it in the end?

I Hope you are still enjoying my old girl.

Cheers

Mike

[bigV8]

Mike - Funnily enough run the car today and the noise dissappeared after a couple of miles - still trying to figure what it could have been - but good news its no longer there !!. Car still a huge grin factor for me - think it really is the most fun car of all the cars i have ever driven -