Hi, James -
I don't know about Donald coming up with the idea. Similar shims are on my
'73 Midget, my '96 Miata, and were on my wife's '92 Dodge Spirit so it isn't
just Healey brakes that can squeal. While I can't cite the specific
physics, I believe the shims work by separating the surfaces of the brake
piston and the pad backing plate to prevent them from vibrating against each
other. The vibration of the pad is excited by the turning rotor, which is
transmitted into the piston. The shims probably modify the relative
frequencies of vibration to prevent them from reinforcing each other.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC USA
-----Original Message-----
From: owner-healeys@autox.team.net
[mailto:owner-healeys@autox.team.net]On Behalf Of James Lea
Sent: Thursday, October 06, 2005 6:11 PM
To: davidwjones; healeys@autox.team.net
Subject: Re: Anti squeak shims.
Thanks for the input guys. The consensus is that they work but I still can't
figure out just why they work. Since they are on the back side of the pad
though, how do they effect the pad in a way to keep it from squeaking?
Vibration? I understand that they were an idea that Donald came up with
after the first cars developed the problem. Cheers, JL
James Lea
2 West St. PO Box 25
Rockport Maine 04856
1952 MG TD Vintage Racer
1953 Triumph Mayflower
1958 Rover P4
1962 Austin Healey 3000 BT7
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