Don Dunbar wrote:

Hi Paul,
It has been some time since my last communication, I have been busy
with work and have put in many hour to complete my engine mounts. I
have followed the news letter on Finn's problems and have

my own opion

to the end result. I have attached photos of my mount

construction for

all to view and comment. The rubber bushing's that I have

used have a

higher operating temp than the Barry natual rubber mounts.

I believe that Finns problems with his mounts are as per

what you have

said that they are not designed to be used in the method he

has used

them.

There are manufactures guidlines for the tension and compresion for
these mounts and with heat and the method that Finn has

used them will

generate more heat and wear the bushing out fast. There are other
bushings availiable with a range of operating temp's from

80c to 200c,

this is the operating temp's not the melting piont of the bushings.
Regards Don Dunbar

Looks good Don. Looks like you picked up more than just six
pan bolts. How many were you able to pick up? I assume it
clears the stock 91 turbo.

Barry does not make natural rubber anymore as far as I can
tell. Natural rubber is still used in a lot of conical
aircraft motor mounts that I have seen. Natural rubber is 180
F. Barry now uses neoprene which has a temp limit of 200 F.
Barry can supply silicone on special order with a temp limit
of 500 F. Chuck Dunlap made his own rubber mounts using cut
washers out of silicone sheet rubber glued together with red
RTV. How are they working Chuck?

Paul Lamar

The silicone main part that is bearing the weight is holding up like
new. I am now using O rings for lateral support, purple in the crude
drawing I made. I was using small pieces of 1/8" silicone sheet wrapped
around the bolt, but did not last too long. The hole in the MM bracket
needs to be bigger so that a thicker center cylinder could be used. The
O rings do not appear to be holding up any better. The hole is now 5/8",
needs to be 3/4" or bigger.

Chuck

Chuck I know AC Spruce does not have any of it but McMaster
Carr sells glass cloth reinforced silicon sheet rubber that is
tougher.

Paul Lamar

I think I forgot to attach Chucks sketch.

Paul Lamar
 
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