Brake proportioning valve install

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Victor H
Posts: 252
Joined: Tue Apr 03, 2001 1:01 am

Brake proportioning valve install

Post by Victor H »

I have too much rear brake bias.
Has anyone ever installed a brake proportioning valve?

What did you use?
where did you install it?
What advice, parts, sources do you recommend?

thanks
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73notch
Posts: 711
Joined: Wed Jan 29, 2003 12:01 am

Post by 73notch »

ive heard good things about the wilwood proportioning valve. Thats what i plan on eventually getting, its relatively cheap too. Normally, i see them mount it somewhere on the center tunnel inline with the rear brake line.

summit has them for like 40 bucks
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Victor H
Posts: 252
Joined: Tue Apr 03, 2001 1:01 am

Post by Victor H »

Just had my mechanic install a Wilwood, 7 position, lever type, brake proportioning valve. Mounted in the driver's side kick panel in reach of the driver. I can only say that the difference in brake balance is night and day. Definately just what was needed to restablish the right brake balance.
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73notch
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Joined: Wed Jan 29, 2003 12:01 am

Post by 73notch »

Do you know the difference between the lever and the knob style proportioning valve? All i know is the lever one costs alot more.
Victor H
Posts: 252
Joined: Tue Apr 03, 2001 1:01 am

Post by Victor H »

Yes, the lever type is much more expensive. However, here's the plus:
1) Only 8 settings so easier to find the "right" adjustment
2) If it gets bumped easy to find the right adjustment again.
3) Easier to adjust while driving the car especially if you go too far and need to go back to the previous setting. And, under some conditions you might want to change brake bias and then back (different traction conditioins)
4) Dial / screw type is perfectly fine, but harder to find the same setting without brake pressure gauges.

Something I didn't know is that at low brake line pressures the differential from front to back is 1:1 (i.e. no differential).
However, once you find a setting you like it works this way.
For example: Say you set the proportioning valve at 400 psi (you don'[t know the psi setting, but this is how it works). Below 400 psi front and rear brake line pressures are the same.
Above 400 psi, the ratio then changes to 3:1. That is for every 3 psi the front brake pressure goes up, the rears go up by one psi.
I've played with it and it works great and was exactly what I needed. My guess is that most people don't need this especially with stock brakes but on my set up with big single pistons in back and 4 small pistons up front per caliper, I had way too much rear brake bias. hope that helps with understanding how these things work.
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