Brake Proportioning Valve

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Apr 12, 2008 | 06:17 PM

RedBandit

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Brake Proportioning Valve

Hello,

In the past (few months back) I posted some questions about having problems with my rear ABS brakes on my 1993 ford F150, 2wd, 5.0L V8. What was happening is that the front brakes were/are grabbing very hard, and the back brakes look like new. No leaking rear brake cylinders, no collapsed brake lines. I went to the dealership to get pricing on a new proportioning valve, they wanted almost $400.00. No way I was going to pay this.

My question is. Can I bypass the proportioning valve and run straight from the little block ahead of the valve directly into the line for the back brakes, which would bypass the valve? Will this work. If so, what can I do to keep the ABS light from coming on on the dash.

I have two pictures. one of the Proportioning Valve (I think that is what it is) and the other of some block, which I do not know what it is. I am not able to attach the pictures to this thread, unless someone can tell me how. I can also email them.

Thanks

Red

Apr 12, 2008 | 07:35 PM

RedBandit

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I found out what I thought the proportional was. I actually is the modulator valve. So the little block that has sits on top of the chasis is the actual Prop valve (It looks so simple).

What exactly does the modulator valve do? Do these cause braking problems? Could the dirt I found in the screen on the inlet of the valve cause the problems I have been having?

Thanks

Red

Apr 12, 2008 | 07:38 PM

Moore558

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By grabbing very hard do you mean they're locking up or just wearing real fast?

Apr 12, 2008 | 07:50 PM

RedBandit

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The front brakes lock up. The back brakes are like new. Could the modulator valve cause this? From what I have read elsewhere, you can bypass the modulator valve and still get normal braking, just no ABS. Or could the dirt in the line be causing the problem?

Thanks

Apr 12, 2008 | 07:56 PM

Moore558

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Hmm. Have you looked at the front pads and made sure they're not contaminated (grease, water, etc.,.)? You say that the brake hoses are not collapsing but does that mean you replaced the hoses already or they're somewhat new?

Apr 12, 2008 | 08:08 PM

RedBandit

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Yes, I have recently changed the front pads and rotors. No leaks. The break hoses were changed not long ago (Maybe a year or so).

Apr 12, 2008 | 08:36 PM

RedBandit

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I will try the modulator valve again, after cleaning the inlet port, but if it still does not work, is there anything wrong with bypassing it, beside not having RABS?

Thanks

Red

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Apr 12, 2008 | 09:43 PM

bluesman2333

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Front brakes can wear out due to the rear brakes not working at all. I would suspect the rear brakes as in cylinders or adjustment before any valves.

Apr 12, 2008 | 09:51 PM

#10

frederic

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From: New Jersey

The front brakes do about 65% of the work on a pickup, more for extended cabs, more for crew cabs.

Why not purchase an aftermarket manually actuated brake proportion valve from any of the speed shops - retail or online - about $50-60. The advantage is when you load the truck down (towing, hauling, etc) you can adjust it a bit to your liking. I installed one on the frame rail of my crewcab about 7 years ago... works great. Just shoot the ****'s stem every once in a while so it doesn't freeze up if you ever want to adjust it.

Apr 13, 2008 | 06:17 AM

#11

RedBandit

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Quote:

Originally Posted by jr32560

are the back brakes working at all?? have you jacked the rear up and checked?? they have a problem with the rear brake cylinders locking up on these-I have had 2 different trucks do it!!!

I did put the truck up on a hoist and ran it. When I applied the brakes the brakes were trying to engage, but chattered.

I currently have the ABS Modulator Valve out, would it hurt to bypass it to rule out that it is a valve problem? I have to replace the brake line anyways, as l was damaged when I removed it.