On Fri, 2 Aug 2002, Skip Montanaro wrote:
> Chuck> Bought two Tiltons to replace the one TR one [for less money, and
> Chuck> now I have a real duel circuit].
>
> This may seem like a dumb question for the racers out there, but how do you
> install two Tilton master cylinders where one resided before? What's the
> effect of having to yank the power brake unit?
It's really not that dumb of a question...
Keep in mind that your stock TR6 brake MC is really a dual circuit setup
but that the two circuits use the same (stepped) bore in the MC.
Racers like to have the best pedal "feel" they can get. THey need this in
order to "threshold brake". In other words, you want to brake as much as
you can without lockup. As you can imagine, brake lockup "at the limit"
can be thrilling at best and downright scary (or fatal) at the worst. But
when you have good pedal "feel", you can make minute adjustments to the
amount of pedal pressure you apply with _predictable_ results.
Part of the process is being able to change the bias from the front brakes
to the rear brakes.
Racers can control this brake bias in a couple of ways. One is with the
bore of the various MC's, Tilton offers several size brake MC's. The other
bias control is either with a "bias bar" or with a propotioning valve (or
both). To actuate two MC's at the same time, you need a "bar" between
them. The brake pedal actuates the bar, and there is a special nut on the
bar that can move left/right. In a dual MC setup, this bar is threaded and
you can connect a remote knob to it which aloows you to turn the threaded
rod which moves the pivot point to change the bias. Generally, there is a
knob within easy reach of the driver that you turn to achieve the change
in brake bias.
There is an additional benefit for the dual MC setup - if you lose a
caliper (or you rip one corner off in a shunt), you should still have
braking control on the other end of the car to get _some_ braking.
The effect of yanking the brake booster is that you need more pedal
effort, but you can then really stab the brakes hard before ultimate
lockup. This translates to more braking control.
FWIW, on my race car, I still have the stock TR6 MC and brake booster. In
warm weather and reasonably warm track temps, it is fairly easy to make
controlled stops without lockup. But when the track temps go down below
about 75 degrees (F), the threshold between light braking and complete
lockup compresses to just about nothing. On those days, I smoke the tires
on nearly every corner.
I have to switch to a better braking system sometime soon because at $180
per tire, it's really easy to run out of money from the racing budget
after a few large lockups.
> Skip
I hope this answered your question.
rml
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