Brake "Proportioning" Valve
Thread Starter
Instructor
Joined: Jun 2001
Posts: 229
Likes: 1
From: Uxbridge MA
Brake "Proportioning" Valve
I have been fighting a problem with my brakes (what's new). I have bled then several times once with a power bleed at a shop and another time with a 2 man team. I replaced all 4 flex lines with SS. I have been able to get the brake light in the vehicle to go out for a short time, but eventually it comes back on. The brakes are manual and they don't feel as firm as I would expect. The top of the pedal is soft, 1/3 way down they harden up. I had to do a hard stop the other day and the car pulled aggressively to the left front.
I have no fluid leaking. I am wondering if the valve is causing me a problem. I noticed most corvette places have discontinued carrying this item or they are $200 for a rebult with a $75 return for a core. Anyone know of other places I can purchase this item(besides ZIP, Ecklers,CC,The Doctor) or another solution. Thanks.....
--Andy
I have no fluid leaking. I am wondering if the valve is causing me a problem. I noticed most corvette places have discontinued carrying this item or they are $200 for a rebult with a $75 return for a core. Anyone know of other places I can purchase this item(besides ZIP, Ecklers,CC,The Doctor) or another solution. Thanks.....
--Andy
Burning Brakes
Joined: Aug 2000
Posts: 883
Likes: 2
From: Hilton Head SC
Re: Brake "Proportioning" Valve (andyg)
The valve on a '69 doesn't proportion anything. It senses pressure differential between your two brake circuits and lights the light when there is a difference. Use the Forum search. There's tons of info on the subject. Dukman's right, the switch usually does not go bad, so there's a problem somewhere. It could be as simple as bleeding, if you're lucky.
Racer
Joined: Jun 2001
Posts: 289
Likes: 0
From: Duluth GA
Re: Brake "Proportioning" Valve (JSB69)
Andy,
I had the same problem with the brake light.
My mechanic said that the proportioning valve was the cause.
I didn't quite understand why, but repalcing it fixed the problem.
I had the same problem with the brake light.
My mechanic said that the proportioning valve was the cause.
I didn't quite understand why, but repalcing it fixed the problem.
Race Director
Joined: Dec 2000
Posts: 10,896
Likes: 2
From: CO
Re: Brake "Proportioning" Valve (Pat 69BigBlock)
Its possible that there is some blockage in the valve. The proportioning is done by changing the size of the pistons in the rear caliper. At least thats what the guy from Vette Brakes said about it. :cheers:
Drifting
Joined: Feb 2002
Posts: 1,987
Likes: 3
From: Manchester, Dead Center in the Middle of TN 25 miles to Jack Daniels,10 miles to Geo Dickle, and .8 mile from the Liquor Store at I-24 Exit 114
St. Jude Donor '05
Re: Brake "Proportioning" Valve (flood)
OK, OK, This is one of those "Once up on a time" or " You ain't gonna believe this $4it" but I have addressed this before and it is definitly a problem.
Now...................Take a real good hold on the steering wheel and try to stomp the brake pedal throooooough the floor !!!!!! Yes, act like it's a big snake about to bite you and try to stomp it through the floor!
I told you you weren't gonna believe me, But when I woked for a MOPAR dealer we had several cases just such as yours and this was what the factory represenitave told us to do.....................it usually worked if it was the valve.There is a ball and a spring inside the block and it seams like the shock to the valve frees the stuck ball and cures the problem. Hey what have you got to lose???? JIM :smash: :smash: :smash: :smash: ;)
Now...................Take a real good hold on the steering wheel and try to stomp the brake pedal throooooough the floor !!!!!! Yes, act like it's a big snake about to bite you and try to stomp it through the floor!
I told you you weren't gonna believe me, But when I woked for a MOPAR dealer we had several cases just such as yours and this was what the factory represenitave told us to do.....................it usually worked if it was the valve.There is a ball and a spring inside the block and it seams like the shock to the valve frees the stuck ball and cures the problem. Hey what have you got to lose???? JIM :smash: :smash: :smash: :smash: ;)
Thread Starter
Instructor
Joined: Jun 2001
Posts: 229
Likes: 1
From: Uxbridge MA
Re: Brake "Proportioning" Valve (JSB69)
Thanks for the replies. I have read the searches on the forum, but there were several answers. A few have replaced this "Valve" which solved the problem. My understanding is this "Valve" is a switch which when activated locks out a portion of the brake system. During bleeding this switch can be activated accidently causing an improper flow to the caliper you are working on. The reason I am questioning the switch is I had this problem with the brake light and soft top pedal before a complete rear end rebuild. I had new TA's installed and setup with .002" to .003" run-out. I could still have a bad caliper, but ...... I'll have to try a bleed again and watch the amout of fluid coming from each caliper to see if it is consistent......
--Andy
--Andy
