Author Topic: Power brake adjustment  (Read 6448 times)

dab67

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Power brake adjustment
« on: July 24, 2007, 11:48:03 PM »
Ok what do I need to adjust or change,,,,,,,,,,,, The first time I drive my car and I step on the power brakes, they grab so hard they almost put you through the front window. After that initial braking they begin to adjust are fine after about the 3rd or 4th stop. What causes this? air? unbalanced action from the front power brakes and the back brakes? wrong size brake booster? I have a 9" booster or how about a bad power brake master cylinder? Or none of the above!!!!!!!!!!!!!!! :-\ ???

Dave

GaryL

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Re: Power brake adjustment
« Reply #1 on: July 25, 2007, 12:35:23 AM »
Too much pressure to the front brakes. What is your setup? factory or after-market.
Gary

Lemans Blue X33. DZ, M20, manual steering. Only BU code rear end is original.

JohnZ

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Re: Power brake adjustment
« Reply #2 on: July 25, 2007, 01:31:33 AM »
That's frequently a classic symptom of the front system metering valve (the round one below the master cylinder) being stuck open, which causes the front brakes to engage before there's any engagement at all of the rear drums. That valve (when it's working) doesn't allow any fluid displacement in the front system until the rears see 30-40 psi, to get the rear shoes out to the drums for a balanced application.
'69 Z/28
Fathom Green
CRG

Charley

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Re: Power brake adjustment
« Reply #3 on: July 25, 2007, 02:01:08 AM »
That's frequently a classic symptom of the front system metering valve (the round one below the master cylinder) being stuck open, which causes the front brakes to engage before there's any engagement at all of the rear drums. That valve (when it's working) doesn't allow any fluid displacement in the front system until the rears see 30-40 psi, to get the rear shoes out to the drums for a balanced application.
..........  I did not know that....Cool.

dab67

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Re: Power brake adjustment
« Reply #4 on: July 25, 2007, 11:36:33 PM »
Gary:

As far as I know, they are factory pb.

JonhZ: Thanks for the info on where to look!!!!!!!! As usual, CRG comes through again. I will check the valve and see what is happening. I presume  I can change the valve correct?

Dave

JohnZ

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Re: Power brake adjustment
« Reply #5 on: July 26, 2007, 02:46:44 PM »
Gary:

As far as I know, they are factory pb.

JonhZ: Thanks for the info on where to look!!!!!!!! As usual, CRG comes through again. I will check the valve and see what is happening. I presume  I can change the valve correct?

Dave


New reproductions of the metering valve are now available, and an outfit in California called "Karp's Brake" can rebuild them - see the "Brakes and Suspension" section at www.camaros.net. Heartbeat City has a rebuild kit, but I'm not sure if it has one of the internal cup seals.
'69 Z/28
Fathom Green
CRG

GaryL

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Re: Power brake adjustment
« Reply #6 on: July 26, 2007, 04:53:59 PM »
I got my metering valve (the round one) done by Karp's Brake in So. Cal. (909)985-0800 for $65. A note, the rubber cover on the button is not reproduced, at least that is what Karp's told me. Brakebooster.com did my booster and metering valve bracket. Very nice in gold zinc
Gary

Lemans Blue X33. DZ, M20, manual steering. Only BU code rear end is original.

 

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