brake proportioning valve

tamanaco · #1 (**permalink**) 09-22-2007, 05:56 AM

Does the BackDraft Racing car have brake proportioning valve? If it does is it adjustable? The reason for my question is the front seem to lock up pretty quick in an emergency braking situation! I'd like to try to improve this.

cbreez · #2 (**permalink**) 09-22-2007, 06:53 AM

the backdraft roadster DOES NOT come with a proportioning valve. There are several factors that make wheels lock-up...tires, weight distribution, the brake pads....a proportioning valve helps overcome these variables. There are many after-market sources.

Jerry Clayton · #3 (**permalink**) 09-22-2007, 07:56 PM

usually a brake problem(front lockup) is caused by something at the other end of the car( rear brakes inadequate) from design issues or adjustments.
Bleed the brakes, check pressure at all calipers,you should be able to get over 1000psi---
I'll bet your rear brakes aren't working properly

Jerry

tamanaco · #4 (**permalink**) 09-23-2007, 06:22 AM

Did find that proportioning valves are for rear lock-up based on web search. I do know the rears are working based on the brake dust on the wheel, they just may not be working as hard as they should be? Like the idea of checking pressure, but that doesn't sound all that easy to do. high pressure gauges and breaching the system? Got any good ideas on how to do this?

Dwight · #5 (**permalink**) 09-23-2007, 07:28 AM

What is the pressure generated in the brake system?

Dwight

Bailey · #6 (**permalink**) 09-23-2007, 10:54 AM

What tire combo are you runnung. #260 probably came with sticky drag radials on the rear. Check the treadwear rating on side wall. The higher the number, the harder tire. If you have a sticky pair on the rear, and just reguler street tires on the front, this would happen pretty easily. When was the least time you bled the brakes?
Cheers,
Richard Bailey

cbreez · #7 (**permalink**) 09-23-2007, 11:00 AM

You didn't mention if this was straight line lock up or corners...I like to keep things simple....looking at the disparity in tires sizes, front smaller and rear much larger and wider, it is not surprizing at all that the fronts would possibly lock up sooner. A lock up can be from overloading the tires...an easy quick solution is to shift weight rearward. A proportioning valve is mostly used for rear wheel lock up because of weight transfer in racing situations, you see it all of the time on TV,but it would work for a street application if you wanted to play with it....lot of variables here...