Brake setup: Adjustable Proportional valve

[Schulmann]

I did a couple of modifications to my brake system:
Installed SRT10 calipers in the front and moved the old front brakes to the rare while keeping the stock Master cylinder and the stock pro valve. Result is greate, much better braking and system still works after an hour on the track. However pedal feeling is not as good.

So after 1 year of use of this system I decided to change the master cylinder and still keep the stock front prop valve. Result: pedal feeling is greate but rear wheels are locking up ...

Question: should I install an adjustable prop valve. Is this mandatory with this setup ?!

 

[Tom F&L GoR]

Technically you should have had rear lockup a year ago, I believe.

The original 2000 brakes were 38/42mm front and 36mm in the rear. The stock proportioning valve limits pressure to about half that of the front brake lines (under maximum braking.) However, even though the pressure is half, by putting the front calipers in the rear, you have more than doubled the area over which the brake fluid pressure operates, which should have more than doubled the rear clamping force.

By going to the Gen 3 MC, which is larger diameter, your pedal travel will be less because for each inch of travel you are delivering more fluid. The pedal should also feel stiffer, because for each inch of travel you are delivering more fluid. (repeat)

In any case, it seems you need an adj prop valve, and I can't figure out why you didn't need it before now. The MC diameter is the same for front and rear systems, so while it will change the pedal feel, it should not change the relative braking proportion front to rear.

 

[Boxer12]

Absolutely, you need one. Get if from Dave (Big Brake guy)...if you don't have CAN source.

 

[Schulmann]

Good advises. I already have the prop valve from Dave. I just got the brake lines ... lets install it.

 

[Schulmann]

What a change I installed this valve.
For the moment the knob is all the way out for safety.
I will tune it while we have a little rain.


Really strange that I didn't need this valve before.
Actually 3 weeks ago I locked up my rear wheels on a track and I spined out.
I downshifted too late and braked strong at the same time.