[DeTomaso] master cylinder advice

[JDeRyke at aol.com]

In a message dated 3/22/11 6:27:38 PM, spkorb at gmail.com writes:

> I just put in a step bore master cylinder and booster from Precision 
> Proformance.  I have stock brake calipers but there is plenty of volume from 
> that setup.  The master appears to be a unit off of a GMC van.  I honestly 
> have never been happier.  I'm still getting used to having brakes that work 
> :)
> 
I also use that same power booster & MS, which mounts flat to the firewall 
with no angle. It really improved the stopping. I run Wilwood Superlite ll 
four-piston calipers in front & Porsche 911 2-piston (front) calipers in 
back, with a manual proprtioning valve in the rear circuit. Both calipers are 
larger than stock. One of my friends uses the stock booster with 6-piston 
fronts and 4-piston rears and very wide tires f & r, and while his car stops 
like the Hand of God grabbed it, the pedal goes nearly to the floor. IMHO, he 
desperately needs a bigger bore master for both ends!
Rule of Thumb: if you CANNOT lock a wheel in a panic stop, you need 
improved brakes. If you CAN lock a wheel, you need bigger/wider tires. And as an 
addendum, if your panic-stop lockup is in the rear, you need a proportioning 
valve to rebalance the system for the parts   you are using (including tire 
sizes). 
Note the stock prop-valve is non-adjustable, is in the front brake circuit 
and was designed to balance all-stock brakes with 185-70 front tires and 
205-70 rears. if ANYTHING has been changed, the valve is wrong and cannot be 
adjusted. A manual-adjust prop-valve will allow you to re-balance your system 
as it now exists. Small gauges will help as well; the circuits will develop 
around 1000 psi line pressure in the rear and up to 1400 psi in the fronts. 
Aeroquip lines are a real safety improvement at such pressures! Good luck- J 
Deryke