Noisy Bushings and more.

[mamirkalali@lucent.com]

Ken,
I just installed polyurethane bushings in my '86 TVR 280i. Both a 
friend and my  mechanic said that I may experience noise from these 
bushings. The bushings did come with small packets of grease (red ?) 
which is supposed to eliminate the noise. I suggest that you apply 
some lithium grease to the bushings/
BTW. polyurethane is not the same as Delrin. Delrin is an excellent 
material for a variety of applications excellent dimensional 
stability, high dielectric constant, low moisture absorption and more. 
Polyurethanes are two part polymers that offer a great
deal of design flexibility. They can be tuned to the application (very 
soft to extremely hard) by varying the relative composition. However, 
they have weakness such as high
moisture absorption and they are dimensionally unstable (varying 
shrinkage rates). In automotive applications, they are considered to 
be of higher performance because they are harder and perform more 
consistently over their expected life.
Rubber bushings, on the other hand, change over time. The vocalization 
process continues until the rubber becomes hard enough (brittle) to 
crack under load. Ironic that, before the rubber bushings crack, they 
ARE harder and perform JUST AS GOOD as the polyurethane ones (the 
change in suspension geometry is a whole other story ........)
So if I had rubber bushings that looked worn but not cracked, I would 
not change them unless the ride became unbearable.
Regards,
Moe

application/ms-tnef