hold off valve - Team Camaro Tech
Brakes, Suspension & Steering Conversion questions, Steering & Handling

 
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post #1 of 5 (permalink) Old Sep 8th, 10, 12:14 PM Thread Starter
jeff
 
Join Date: Sep 2009
Location: essex iowa
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hold off valve

I have a 1968 camaro that I converted to power brakes but keep the drum brakes. I was wondering about the hold off valve is it necessary? I am having problems with my front brakes grabbing before the rear brakes. I looked up on the forum and all i could find was a link to the following http://www.camaros.org/suspen.shtml#BrakeRegulatorValve but it really doesn't say? Could the valve be bad? Any help would be greatly appreciated.

Thanks,

Jeff
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post #2 of 5 (permalink) Old Sep 8th, 10, 01:03 PM Thread Starter
jeff
 
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Re: hold off valve

PS. I have read the other forums on this and i am just as confused one says it gives the back brakes more pressure before the front and the other says it does the opposite?? So which one is it? and is it necessary for a all drum brakes that have a power booster?
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post #3 of 5 (permalink) Old Sep 12th, 10, 04:33 AM
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Re: hold off valve

Converting an all drums brake car from manual to power shouldn't change anything except brake feel. So, if your car didn't have the hold off, it shouldn't need it now. That valve wasn't originally installed on all cars. Therefore, it isn't a "must have" item. You might just make sure you bled everything well and have adjusted the shoes correctly.

Oh, almost forgot. From what I understand, the hold off basically kept the pressure off the rear brakes until the front started the stopping process. I thought I read somewhere that all of that started (they saw a need) when people were spinning out in snow and slippery conditions.

All of this is off the top of my head. I'd have to dig around a bit to prove it... ;-)


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post #4 of 5 (permalink) Old Sep 12th, 10, 06:25 AM
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Scott
 
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Re: hold off valve

This topic comes up repeatedly here and at CRG:

"The function of the round metering valve (or "hold-off" valve) is to allow the rear system to see 30-40 psi (which moves the rear drum shoes out into contact with the drums) before the front discs see any pressure, to avoid disconcerting "front brakes first" on pedal application, which causes "nose-dive" at low speed"

It's not used on a drum system and the vendors don't refer to it by it's proper name, nor the proportioning valve on the frame.
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post #5 of 5 (permalink) Old Sep 12th, 10, 07:39 AM
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Re: hold off valve

Quote:
Originally Posted by Sauron67MM View Post
This topic comes up repeatedly here and at CRG:

"The function of the round metering valve (or "hold-off" valve) is to allow the rear system to see 30-40 psi (which moves the rear drum shoes out into contact with the drums) before the front discs see any pressure, to avoid disconcerting "front brakes first" on pedal application, which causes "nose-dive" at low speed".
Right. I was originally thinking this and talked myself out of it somehow (holding pressure ON rear, not off)...

Quote:
Originally Posted by Sauron67MM View Post
It's not used on a drum system and the vendors don't refer to it by it's proper name, nor the proportioning valve on the frame.
Right! And they will not be conviced of otherwise! It is plainly written in the...Fisher Body manual (Chassis Service Manual? Been awhile since I read it.), too.


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