Brake bias

[redmist]

No this is not a discrimination issue , this is about getting maximum braking force. After my brake upgrade I can't quite get the paint to fly off like the Kuhmo tire commercial but pretty close.
The problem is the front brakes lock up first and exclusively.
My research, although not conclusive, points to yanking the existing proportioning valve and replacing it with a adjustable proportioning valve.
I would be very happy for any alternatives such as modifying the existing valve.
Thanks.

 

[Yoda]

There are a few things that come to mind that can cause the front brakes to lockup as you've described.. If there is no air in the system, no glazing, sticky caliper pistons and everything at the brakes appears solid and working correctly.. then it sure does sound like the proportioning valve (Control Valve).

The purpose of the proportioning valve to prevent wheel lockup The valve is designed with a "bypass" in case of brake failure (usually the front) so the back brakes still function. Do you have a brake warning light on?

Bud

 

[redmist]

Bulb and circuit are good...no light.
The brakes are working as the e-brake works and rotors are shiny (or the pads are seriously rubbing).

 

[Hib Halverson]

Redmist,

Did your upgrade kit come with a new proportioning valve?


If not, you might contact them for advice. they may have what you need.

With the dirl oval cars we use two master chylindars and a balanace bar between and we can adjust rear bias on the fly. If the car is to tight, dail in a tad more rear brake to turn it in.

They make adjustable proportioning valves that do the same thing.

We also a have a shut off on the right front for when the track gets slick. Some guys don't even install a RF brake


Keith

Actually a common misunderstanding is that balance bar master cylinder assemblies and proportioning valves do the same thing. They do not. The balance bar set-up truly controls brake bias with different pressure levels for a given pedal travel to the front and rear axles. A proportioning valve, typically installed in the rear brake circuit, is more like a regulator in that it bleeds off brake pressure above a certain level but below that level pressurizes the two brake circuits to the same level. While the end result is similar, the two systems are not alike.