Actually I was going to use a bias bar and a proportioning valve (instead of
the 10# you use in the rear circuit). I thought that using both might give
me a greater degree of adjustability. But maybe not...
-----Original Message-----
From: Bill Babcock [mailto:BillB@bnj.com]
Sent: Friday, August 01, 2003 5:18 PM
To: 'Hugh Barber'; 'fot@autox.team.net'
Subject: RE: Brake MC sizes?
I tried a proportioning valve instead of a bias bar in an H Production
Rabbit years ago, and didn't like the result. The rear brakes felt more
jumpy--that is, they don't seem to get force applied to them smoothly, but
rather in jerky increments. It could be that proportioning valves have
been greatly improved since then, but I notice that most race cars at the
high end of preparation use a bias bar instead. For example, my Radical
came with a cockpit-adjustable bias bar. There may be other reasons why
this seems so popular, but proportioning valves seem like a far simpler
solution than a bias bar, I'd assume that if they worked equally well
there would be no call for bias bars at all.
-----Original Message-----
From: Hugh Barber [mailto:tr6nut@sbcglobal.net]
Sent: Friday, August 01, 2003 4:40 PM
To: Bill Babcock
Subject: RE: Brake MC sizes?
Bud,
Thanks for the advise, especially the comparison of the 5/8 to .75. I had
planned on using a 2# in the front and and adjustable proportioning valve
(Wilwood) in the rear.
Hugh Barber
-----Original Message-----
From: Bill Babcock [mailto:BillB@bnj.com]
Sent: Friday, August 01, 2003 9:49 AM
To: 'Hugh Barber'; Fot
Subject: RE: Brake MC sizes?
Since TR6 has the same fundamental braking system as TR3/4 then perhaps my
recent experience might be helpful. Peyote has both front and rear master
cylinders at .75 . The front cylinder was bored to that diameter from .70
so that the same rebuild kit could be used for both cylinders. The brake
bias is set with plates that have various lengths between the center hole
(connects to pedal) and the each end where the cylinders connect. Many
people feel that 5/8" is a more rational bore for the front brake to give
appropriate mechanical advantage, but I don't mind trading pedal hardness
for easier modulation, and if you get a little air in the lines or some
other reason that your pedal goes soft, the larger bore lets you pump some
brake in while the smaller ones may not--or at least will take more
strokes. That's not a great consideration, but it's real world.
I tried a 5/8" recently because people I trust said it would work better.
Didn't like it, I'm back to .75.
One more thing, make sure while your fiddling around to use appropriate
line pressure compensation. Right now I'm using 2# in the front and 10# in
the back, and I really like it. There's no drag to speak of but the pedal
applies brake with just a tiny bit of travel. I expect an improvement in
lap times as I start being able to count on my brakes being there. I had
been pumping once or twice to get a firm pedal. Not a confidence builder.
-----Original Message-----
From: Hugh Barber [mailto:tr6nut@sbcglobal.net]
Sent: Thursday, July 31, 2003 8:48 PM
To: Fot
Subject: Brake MC sizes?
Hi All,
I'm replacing the Brake Booster/Master Cylinder with dual master cylinders
on the TR6 vintage racer. Does anyone have any suggestions as to which
sizes would be a good starting point? I know that I could probably sit
down and figure out something close, but I figured if somebody might have
already done this, why reinvent the wheel?
Thanks,
Hugh Barber
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