Hello Dave:
I also race two TR4A's one IRS and one solid axel. Your problem is
not unique and is not completely fixable. The problem is that in hard
cornering the rotor flex pushes the front caliper pistons back into
the caliper a bit. To fix this problem you can get the residual
pressure valve. TR3's have these almost routinely you can try
local club's. CNC is a company located in San Diego that makes
lot's of brake products including the residual pressure valve.
Unfortunately, I'm not sure what pressure is necessary to hold the
caliper pistons in position. I would try the lowest pressure (4lbs)
first.
I bought a dual swing mount pedal assembly from them for my car and
with some engineering made a pretty cute and trick set-up.
Good luck
keep me informed-
Mordy Dunst
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Subject: dual master brake cylinders
Author: Dave Page <page@ra.isisnet.com> at INTERNET
Date: 2/15/96 9:11 AM
I have a '67 Triumph TR4A IRS that I have raced a few times in the =
Pacific Northwest (I'm now living in Nova Scotia where cars rot before =
they become vintage-eligible). While racing, I encountered an unusual =
braking problem after taking high-speed corners - that is I'd have no =
brakes upon first pedal depression. After one pump, the pedal would =
return until I took another high-speed corner, and then the problem =
would repeat itself. Needless to say, this was a little disconcerting, =
as it had quite a negative effect on my lap times (didn't do much for my =
confidence either!). I've tried different fluids, checked the slave =
cylinders, checked the master (single), etc, etc. but nothing seems to =
help. I do have the rear shoes adjusted out 2 1/2 notches rather than =
the "street" setting of 1 1/2 but I received this recommendation out of =
the factory competition prep manual. I noticed that on some of the =
pressureolder TR4's, there was a inline valve that kept some residual
pressure = in the rear brake line so that the shoes wouldn't recede too
far from = the drum. This unit isn't available anymore and I'm at a loss
for a = cure. I'm looking at going to dual cylinders for the added safety
= benefits but I'm not convinced this will cure my particular problem. =
Any ideas? Also, If anyone has recommendations as to what size master =
cylinders I should be looking at for my application, I would be forever =
indebted (as if I'm not already!).
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