Heavy suspension knock

[Peter Naulls]

For as long as I've known our Ruby it has had a very heavy knocking noise from the rear end, evident on rough roads or potholes. I've tightened everything I can think of but the problems remains. It's clearly not doing any harm as it's covered thousands of miles like this but I would love a bit of peace and quiet. Any ideas?

[Graham Barker]

A friend had a similar knock and was worried that it was something major. However, it turned out only to be a loose bumper mount.

[AustinWood]

This isusually the attachment of the front of the torque tube to the chassis. Either the big ball joint on the torque tube or the fixing on the chassis, either a ball jointor later Rubbys a rubber bush.
However I think you've investigated those.

[Reckless Rat]

Check that one or both of the rear springs isn't hitting the underneath of the body - if it is/ they are there will be a tell tale mark, usually from the rivet on the leaf clamp.

[Peter Naulls]

Very helpful thank you. Yes Austin, the torque tube adjuster is good and the silentblock bush and bolt are both new. There is some wear in the holes in the mounting plates and I'm at a loss to know how to rectify this in situ, however the through-bolt is tight and doesn't show any signs of having moved.

I will investigate the spring rivet possibility, thanks Reckers.

No bumpers on mine Graham but I understand the principle - it could be something quite unrelated to suspension! I've done the obvious thing of emptying the boot and removing the back seat.

The only thing I haven't worked on in recent years is the friction dampers but the noise sounds heavier than that.

[Barry Townsend]

I had a very similar problem with my RN. Eventually traced it to a broken brake pivot. Gave exactly the symptoms you have, worth a look.

[David Stepney]

I know it is difficult to diagnose funny noises without actually hearing them, but I have a similar knock/heavy rattle form the rear of my RP saloon, especially when carrying passengers in the rear seat. When I was under the car sorting out the torque tube mounting a couple of weeks back, I noticed that the rear shock absorber link bushes were worn and slack. I have ordered all the bits to do this job and hope that this will cure the problem. It may be worth checking these links on your car, Peter.

[Peter Naulls]

Thanks Barry, I can rule out the brakes as they have recently been completely re-built. 

There is a witness mark on the floor where one spring rivet has been touching but I think this pre-dates me fitting new springs. The knock doesn't always occur at the lowest point of the bounce, if anything it seems to be on the rebound.

I spent a bit of time disassembling one damper this afternoon. The link bushes are fine but the holes in the inner arm are worn (where the centre pin goes through at each end). I think I'll start by welding these up and reaming them back to standard although I'm not convinced this is the source of the problem. The friction discs are swimming in oil too so a bit of attention is needed.

My wife did suggest that if I stopped the windows and doors rattling I might stand a better chance of finding the problem. She has a point.

[Nick Turley]

Hi Peter

There were a few years ago some rear springs made that did not hold the shackle bushes tight in the eye of the spring.
That could make a knock.

[Peter Naulls]

That would sound highly plausible Nick, except that I have recently changed the springs with no improvement!