Holdback pressure valve question

Z

zuma

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Joined May 3, 2002

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Discussion starter · #1 · Nov 10, 2003

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I have a 69 with the factory disc/drum setup. The proportioning valve is there but the disc holdback pressure valve was removed long ago. I picked up a old used unit and in the process of taking it apart, the large nut with the O-ring (I am replacing that) sprung off and stupid me, all the parts fell to the floor

. My question is; Where does the small spring belong, under the diaphragm (that looks fine) inside the large spring and sleeve, or ontop of the diaphragm just under the large nut? Is there any other things I should take a look at while I'm taking it apart? also when installing, will a standard manual bleeding of the brakes be sufficent. BTW my brakes seem to be working fine, but If it belongs there shouldn't it be used? Thanks...Mike

 

davidpozzi

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#2 · Nov 12, 2003

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It is needed for only very special conditions, where the choke is on and auto trans in drive, and the car is on ice, the rear wheels will spin because there is not enough rear brake to prevent it. Once line pressure goes over fifty psi, the valve does nothing.

If you have a manual trans, don't drive in snow, you dont need it.
David

 

Z

zuma

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Discussion starter · #3 · Nov 12, 2003

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Thanks Dave, I have an auto 350 with a shift kit. It will never see snow or rain for that matter. I have tried some panic stops with the current setup and only have lock up when I really apply petal pressure, but the front end dosen't pitch or pull, seems ok to me. I want to elimate the half-a$$ coupling that was made to the brake line, replace it with a new piece and just keep the hold back unit off, I guess thats what I'll do...thanks Dave, you are a great resource... Mike

 

KevinW

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#4 · Nov 13, 2003

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Take the guts out of the valve, keep the o-rings and use the valve. That way it is correct looking without the valve working.

 

davidpozzi

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#5 · Nov 13, 2003

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I sent a photo of the valve innards. Hope it helps.
David

 

Z

zuma

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Discussion starter · #6 · Nov 14, 2003

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Got the picture David, thanks again. Kevin, good idea, I'll see what I can do with it..thanks... Mike