Re: Bushings

[AUDIDUDI@delphi.com]

> I've read (in a performance handling book) that poly-eurothane bushings 
> were NOT the way to go.  They tend to seize up in the casing.  This same 
> book recommended (rather highly I might add) Nyliner bushings.  These are 
> metal bushings with replaceable (every year, or earlier for track use) 
> nylon inserts.  This setup is notably more expensive than eurothane, but 
> was said to be far superior, since the nylon inserts were replaceable.

One other consideration: since no one makes polyurethane bushings for Audis
(other than the TQC/4k/4kq control arm bushings offered by Sportwheels here
in the US and Dialynx (?) in the UK), it's kind of a moot issue since you'd
need to spend BIG BUCKS for a mold in order to have a set custom-made.  Any
decent machinist, on the other hand, can turn out a set of Nyliner bushings
for a couple of hundred bucks at most ... the problem with the hard plastic
bushings is that they tend to have rotational freedom in only one plane (as
compared to rubber, which will twist in several directions depending on the
design of the specific bushing) and this will cause the bushings to distort
and/or wear prematurely if not actually bind-up the suspension, which isn't
a *good thing* so far as handling is concerned.  Because polyurethane isn't
as rigid, it doesn't suffer this problem to the same degree (although it IS
still a problem, at least IMHO) but they WILL sometimes cold-flow and seize
to whatever they're locating if the material wasn't formulated properly for
the specific application.  Frequent lubrication will sometimes help prevent
this.

Although far from cheap, the usual solution to this problem is to use metal
spherical bushings and modify the parts to accept them ... this probably is
NOT a good idea for the street, though, as these parts are very suspectible
to excessive wear when exposed to dirt and grit, and they'll transmit noise
and vibration MUCH more effectively.  In some applications, though, I think
you can get away with them ... for instance, I HAD planned to install a set
of camber plates in my '87 5k this past weekend, replacing the rubber strut
bearings, etc.  For the most part, these are less likely to get dirty and I
know people who've had them last 60k or longer in street use, which is more
than I get from the OEM parts...

Of course, as an M.E.-in-training, you probably know this all of this stuff
already, right?   :^)

     _             _              _
    / l       l o l  \       l o l  \  _   _ o  _   _   AudiDudi@delphi.com
   /__l l l / l l l  l l l / l l l /  / l /  l l \ / _  Jeffrey Goggin
  /   l l_l \_l l l__/ l_l \_l l l  \ \_l \_ l l l \_l  Scottsdale, Arizona