OK it talks about this thing in series with the rear brakes. Is this correct for a race only car with skinny fronts and wide slicks out back? I would think the valve would be better fit up front, seems like the front would need the adjustment to keep them from locking up first?

This is the WilWood valve BTW.
This is for the Dynalite Wilwood brakes also.

The way that I understand it is that placement depends on brake type. If you have disck brakes on all four corners I would put it in the front to prevent locking the narrow fronts up. But if you have drum rear brakes you want it in the rear because drum brakes don't require as much pressure to work.

I have those front brakes on my car. I've run a proportioning valve on the front ever since I cooked the front rotors and skidded through both front tires. I had 12" rear drums on the back until last year when I put Mark Williams rear discs on. With the rear discs I had to change the adjustment some but still have the prop. valve on the front.

my brake proportioning valve in right up front. with drums in the rear with no problems, you just have to set it to where you want it, thats why they call it an adjustable proportioning valve.mines to the left of the master cyl.

I have never used a prop valve on any 4 wheel disc brake set up with a mopar master cyl

Put it in the fronts... your trying to slow the fluid
down so you dont lock the fronts... I have disc all
the way around with it on the fronts

The theory is the footprint of the rear tires compared to the front. You are trying to choke off some of the front brake fluid so more pressure can go to the rears for a couple of reasons.. the first reason is the size of the rear footprint. The area on which the tire contacte the pavement. the second ,is to keep the car from nosediving and changing your caster/camber and toe adjustments Kinda like the BUMP STEER theory... I have pressure gauges that screw into the bleeder screws ( one front and one back) and you step on the pedal lets say 1600lbs on the rear and adjust until you get 1100 on the front... I'm not sure about the specs,, but I can look them up.. if you want to borrow the gauges,, let me know and I will send them to you... Ga

How much brake presure is needed to safely stop a car with disk brakes all the way around ? I have a Willwood master cyl with a 1 inch bore and am getting about 900 psi on the front and 1200 on the rear?