79 z28 with brake problems

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#31

06-28-2011 | 10:07 AM

92 RS in training

In the Staging Lanes

Joined: Jun 2007

Posts: 46

From: Fredericktown Ohio

My bad. I didn't realize he was losing fluid. I'll shut up now.

#32

06-28-2011 | 05:00 PM

Lthompson

Thread Starter

Newbie

Joined: Jun 2011

Posts: 25

i have a comp cams vacuum can that i never put on. Im runnin a Comp hydraulic roller XR288hr. At least thats what i told the builder to put in it. 236 intake 242 exhaust at .050. . Ill have to check the rear drums and see whats up. but itll be this weekend before i can do it. Thanks for the help

Last edited by Lthompson; 06-28-2011 at 05:11 PM.

#33

06-28-2011 | 08:30 PM

Hossz28

Newbie

Joined: Jun 2011

Posts: 8

From: Ontario Canada

Quote:

Originally Posted by Lthompson

ok,, replaced master cylinder.. Bench bled it.. Also found i had a bad rubber line in the back.. Was getting no fluid to the rear. Changed it.. Bled lines.. Getting good flood all the way around.. Kept reservoir full. Had good pedal pressure.. Brakes still werent very good.. Drove down the road a while.. Slowly lost brake pressure.. Pedal almost hits the floor again.. Checked fluid later, Rear brake reservoir was empty. But i cant find a leak anywhere.. Gonna bleed again next weekend.

You have to have a leak in your rear brake circuit as it is a sealed circuit trace you brake lines from the connection at the master cylinder down to the proportioning valve then trace the line back to the rubber hose then across the rear axles If none of these lines or their connections are leaking remove the rear wheels and brake drums and inspect the wheel cylinders for leaks the brake shoes and hold down and return springs must also be in place if this is all good its time to call in a pro sorry to say

#34

06-29-2011 | 02:33 PM

kjvforme

In the Staging Lanes

Joined: Jun 2010

Posts: 67

From: Eastern Oregon

Thought I would chime in and add more info. Over time the flex lines will swell on the inside and partially or fully block off the brake fluid from reaching the cylinders and calipers. The only way to tell is by removing and inspecting the inside of the hose, they should be replaced if they look factory.
As for fluid loss I agree, check the inside of the wheels as most likely the seal on the rear wheel cylinders are leaking by. They are not an expensive piece to replace. There may be a bad proportioning valve as well if moisture has gotten into the system.

#35

07-01-2011 | 02:33 AM

Hotchkis

Former Sponsor

Joined: Feb 2011

Posts: 78

Quote:

Originally Posted by Lthompson

I got a 79 Z28 that ive been working on for a while. New motor, new trans, new rearend. Brakes have never worked well. Always have to bleed em just to get em to work a little bit, But still barely work. I get fluid to all four corners just fine. I replaced one line that had a kink in it. Anyway, What should i verify and definately check before i get a new booster and master cylinder? And i think my master cylinder is leaking anyway. Also, is all of the booster/master cylinders on these cars slanted back real bad? I havent paid alot of attention to others in the past. If i need a new booster/cylinder what bore and such should i be looking for? Rear drum, front disc by the way. Any help is greatly appreciated. This is the major reason i dont drive it much. Thanks

LThompson – if the brake master is really bad, it can leak out of the back of the master and down the front of the booster. Even new master cylinders can be bad. Since you’ve replaced it and you’re still losing fluid, it has to be dripping out somewhere. Since you’re having trouble finding the leak, park over a bunch of cardboard, add fluid, pump the brakes. The fluid will have to hit the cardboard if it’s leaking out. Tell Tale signs of leaky wheel cylinders are brake fluid dripping down the tires. Good luck!