"Jim K" wrote in message
...
recently asked re anti roll bar drop links "knocking" and was
pleasantly surprised to find it wasthe ARB bushes that were sh@gged.
Duly replaced with heavy duty items a day ago.

However now I'm getting a "knobbly tyre on road" type noise *in* the
car at 30mph or above - speed related, but not engine related....

Can changing ARB bushes affect tracking for e.g.? or is the firmer
material of the HD bushes likely to be transferring more road vibes
into the "chassis" ? or something else??


I assume ARB means Anti Roll Bar. If so then no, the ARB does nothing to
control tracking or any other part of the suspension geometry. With most
vehicle you can throw them away and the only difference will be increased
body roll.

It probably is that the new bushes are merely transferring vibration that
was already there. Try stroking across the tyre surface to feel if the tread
is uneven. If the tracking is out you can often feel more resistance in one
direction than the other due to the tread being "feathered". Another common
cause of increased road noise is "Blocking" meaning the tread blocks are
wearing unevenly. Slowly spin a raised wheel and look for tread blocks of
differing heights, again stroke the surface, but around the tread this time,
and feel for uneven blocks.
A simple tracking check is to tie a long length of string all the way around
all four wheels. With the steering set straight ahead you can get a rough
idea if the tracking is toeing in or out, and even see if it is a long way
out.

Mike