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Can Proportioning Valve go bad?

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Old 06-30-2002, 08:56 AM
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Can Proportioning Valve go bad?

Well both of my front brakes are stuck on, they will release if you let the car sit over night. But if you try to drive it, they will slowly stick on a little bit more every time you hit the brakes until the car will stop all by itself. This is affecting both brakes equally and the Brake light is on, if I unplug the wire going to the proportioning valve the light goes off. So back to my original question, can this vavle go bad, it is the only thing I can think of that would be wrong.

Any help will be greatly appreciated!

TIA
nick
Old 06-30-2002, 11:12 AM
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Car: '86 TransAm WS6
Engine: 305 TPI
Transmission: Custom TH700R4
Not that I claim to know much about repairing brakes, but My T/A has had every brake component fail at one time or another, so I know about brakes breaking.

The answer to your question is: Yes, the proportioning valve can go bad. From your description, that's what it sounds like. Less likey, you could have some sort of blockage at your wheel cylinders, preventing them from releasing. I'd look at the Prop valve first.

Good luck.
Old 06-30-2002, 02:41 PM
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Thanks for the info speedcat, it really does act just like a line lock. Something is not letting the fluid back.


nick
Old 07-01-2002, 10:05 AM
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One thing that I know from experience about this is that it is very possibly the soft lines that are causing you trouble. From what I understand the inner lining becomes corroded and will block fluid from flowing out of the caliper. I replaced my prop valve when one caliper was acting like yours and it did not fix the problem. I also replaced the caliper twice and still no fix. I got rid of the car before I fixed it, but there was only one thing left to replace. Prop valve goes for over $100 so I'd look at the lines first. BTW if you need a valve I'll sell you mine for real cheap.
Old 07-01-2002, 01:06 PM
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Car: '88 Iroc, '91 RS, and a '70 RS
Engine: 5.7 TPI; 5.0 TBI; ZZ4/T56 on the ag
Transmission: A4, A4, slated to be a T56
A new prop valve will run you right at $55 from GM. Get the part number you need and either go to a dealer, order from www.gmpartsdirect.com, or talk to Dal at Vandevere Olds. Mine ran me $54. Pretty cheap if you ask me. And yes, change out your old lines for new ones, but definitely check and/or change them before you order a new prop valve.

Ed
Old 07-01-2002, 02:39 PM
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ATOmonkey

I sent you a PM atomonkey.

Thanks for the reply's everyone, I have alreadey replaced the soft brake lines and calipers.

nick
Old 07-03-2002, 06:35 AM
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ebmiller88

Do you have the phone number for your connection at the olds dealer, my local dealer wants 100 bucks for the proprtioning valve.

thanks
nick
Old 07-03-2002, 04:04 PM
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Well I do not know if anyone is still checking this, but I replaced the master cylinder today. I found that I was not getting hardly any fluid through it to the front brakes. This seemed to fix my problem, except that the front brakes are still a little tight. If you jack the car up and try to trun a wheel, you can turn it, but it takes a little effort. Aslo the brake light is still on, but the car is driveable now. So if anyone has any ideas feel free to throw the out.

thanks everyone
nick
Old 07-03-2002, 04:49 PM
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don't F around with your brakes. change the prop valve, and the front brake HOSES.

either way they are 13 years old, and I would never feel bad changing a 13 year old part, even if it is good.
Old 07-09-2002, 12:39 PM
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Just so you guys know, I took apart the prop valve and cleaned it. This fixed the Brake light being on all the time.


The brakes are still a little tight, the wheel will not even free spin a single turn. They just do not want to release completly, but you would never know there was a problem if I was not looking for it.

nick
Old 07-11-2002, 06:01 AM
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Car: '88 Iroc, '91 RS, and a '70 RS
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Transmission: A4, A4, slated to be a T56
89BlueTA:

Sorry for the dealy. Dal Slabaugh at VanDevere Olds (800)362-9494. He's the man on 3rd gen info and parts.

Ed
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