80 Corvette Brake Problem Help

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Oct 17, 2008 | 08:11 PM

Randy2red

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Intermediate

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80 Corvette Brake Problem Help

I have an 80 l-82 auto. My brake pedal is hard till I start car up & goes to floor with limited braking ability. No leaks fairly new lines & calipers before I purchased vet a couple years ago but did change driver side caliper due to seepage last year, I bled brakes till my wife's leg could pump no more. Installed a new master cylinder,bench bled till I almost had a blister & no sign of air. Installed,did nothing.I tried gravity bleeding on all calipers tapping calipers with rubber mallett, works well but not a bubble of air,after 2 qts of fluid.When I pump brakes I

hear a squishing sound,I just ordered a new brake booster,could it possibly help or should I take to a mechanic to power bleed system or could I have another problem???Any advise would greatly be appreciated.

Oct 18, 2008 | 04:00 AM

RC81

Burning Brakes

Joined: Feb 2000

Posts: 776

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From: Middleton, Id

Sounds like the booster to me. Mine did the same thing when it went out.

Oct 18, 2008 | 08:00 AM

...Roger...

Race Director

Joined: May 2006

Posts: 16,528

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From: Dayton, Ohio

Quote:

Originally Posted by Randy2red

A bad booster won't cause the pedal to go to the floor.Air in the system or a bad master will cause the pedal to go down.Too much pumping will create zillions of tiny bubbles which are very hard to get out of little hiding places like threads,Ts,elbows and valves.

Oct 19, 2008 | 10:20 AM

FLYNAVY30

Le Mans Master

Joined: Sep 2002

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From: Redacted

Im having exactly the same problem...replaced a brake caliper, and now the pedal goes to the floor with no braking after many hourse of bleeding the system with a manual vacuum bleeder

Oct 19, 2008 | 10:31 AM

ghoastrider1

Le Mans Master

Joined: May 2006

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From: indy indiana

has to be air in the system or bad MC. I believe the booster only effects the effort required to work the system.You guys are starting at the fartherest wheel and making sure the MC always has fluid in it?

Oct 19, 2008 | 04:40 PM

Jon S

Instructor

Joined: Jun 2005

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Quote:

Originally Posted by ghoastrider1

Sounds like the same problem I'm having with my '81 since replacing the calipers. I hope someone finds a solution and posts it. I'm having mine gravity bled this week - will advise.

Oct 19, 2008 | 08:48 PM

FLYNAVY30

Le Mans Master

Joined: Sep 2002

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From: Redacted

well, mine turned out to be a master cylinder...while bleeding the system, apparantly the 40 year old MC gave up the ghost...the cylinder that is pushed by the pedal got stuck all the way forward, locking up the brakes. Pulled the master cylinder off and replaced it, re-bled the system, everything works fine. A new master cylinder is only 30 bucks at Auto Zone and the hardest part of replacing it is rebleeding the system...thats probably what your problem is...especially if your wife was pumping that pedel until her leg fell off. Good Luck!!

Oct 22, 2008 | 08:05 PM

Jon S

Instructor

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Update, as promised: Had the brakes bled one more time today. They decided not to gravity bleed them, but do it the pump and release method we did two weeks ago. Well, after bleeding the rears and finding zero air, they bled the right front and there was a spec of air there. Left front had zero air. Brakes seem much better now.

I'm using DOT 3 Castrol LMA (Low Moisture Absorption) brake fluid.