Rear Suspension

[Joe]

Hi. Need some advice on suspension, rear in particular. When going over a sharp bump in the road (not particularly big) get a very sharp and harsh thud coming up from the rear. This is not my first Triumph and do not remember the suspension being so harsh, in comparison have an 81 Range Rover classic and an Austin A50 and both handle the same bump better. The R/R one might expect but would have thought the TR suspension would cope better than the leaf's on the A50. Have checked everything numerous times and can't see anything obvious. Some time ago replaced the sub frame mounts with Witor150382RM 60 shore bushes. More recently replaced the diff and suspension arm bushes from poly to rubber, this helped a reasonable amount, but still seems harsher than it should be. Sorry forgot car is a 77 2500 TC, on Stag rims and 185/75R14 Tyres run at 28-30 psi.
Thanks Joe

[Alec]

Hello Joe,

is there any sign of the cross member contacting the body. The reason I ask is that later cars had a different arrangement of mountings due to a change in the. nose piece dimensions. The later cars had an extra differential rubber mounting spacer I seem to remember?

Alec

[Richard B]

Try identifying which side this is occuring on.

There are only four contact points on each side of the centre line; Sub-frame mount, shock absorber, Spring and diff mount. It is either one of these eight or something wrong within the rear suspension structure.

Look for loose shock absorber, broken spring or corroded spring mount on the bodywork. Alternatively could be worn or broken diff pin.

I once had crack (rust) in a rear subframe, but this showed itself through the handling, not a 'thud'.

[Joe]

Thanks for responses. Have replaced all of the rear bushes over last couple of years but will check them all again, especially around the diff. have used the Chris Witor tech guide to place all the bushes in their right order. Will try and be more systematic in my process, never a strong point with me. Will give an update when I have a look. Because it does possibly sound like something may be contacting the body.

[Forkie]

How old are the shocks- i fitted new ones before my long lay up, and the bushes already need replacing, perished, and thats sitting still in a dry garage, and not even under load!!! Sounds like it could be a shock rubber gone, but i am sure you would of checked those....

[Joe]

Hi, had a good poke around, no sign of any body contact and all bushes seem to be in the right order and in good condition as they should be, because most have been replaced. Will however change out the shocker bushes as don't know how old they are and easy to do. Did see one of the uni joint covers on drive shaft torn so that needs replacing as well while back there.
Thanks Joe

[Joe]

Update to original post, replaced all shock rubbers and checked shocks for smooth travel, seems better on nearly all bumps and definitely better on the harsh ones. I think part of the problem might be the tyres, they are just very cheap generic brand from one of our big tyre retailers. they transfer a lot of road noise on all but very smooth surfaces.
Joe