1980 brake problems,please help
Thread Starter
Intermediate
Joined: Apr 2005
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1980 brake problems,please help
Hi all, I have an 1980 corvette l-82 automatic with power brakes.I have changed the master cylinder x3 the last one was brand new from full throttle corvette so i know it is the correct one.,I had a mechanic change the power brake booster.I have bled the brakes many times using diff techniques,pump & squirt,drip bleed & vacuum bleed using a hand pump starting from farthest to closest to Master cylinder
My Problem is that I have a good petal which stops the car only with the brake booster disconnected & blocked off. With the vacuum line connected to the booster the petal slowly goes right to the floor.
Any ideas or suggestions would greatly be appreciated.PS my vacuum: headlights have slowed down to the point of needing help & not sure if related to brakes.
My Problem is that I have a good petal which stops the car only with the brake booster disconnected & blocked off. With the vacuum line connected to the booster the petal slowly goes right to the floor.
Any ideas or suggestions would greatly be appreciated.PS my vacuum: headlights have slowed down to the point of needing help & not sure if related to brakes.
Last edited by Randy2red; Jun 11, 2011 at 03:30 PM.
Race Director
Joined: Mar 2006
Posts: 14,112
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From: Florida
To test the master and/or booster, disconnect the brake lines and install metal plugs to at the booster.
With no vacuum, you should have hard pedal after 1/8" depression and with vacuum you should be able to depress the pedal no more than 3/4".
With no vacuum, you should have hard pedal after 1/8" depression and with vacuum you should be able to depress the pedal no more than 3/4".
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
OK, the vacuum line on the brake booster has another end, right? Find it. Trace the line and see if another line branches off it and goes up toward the front of the car, or if the brake booster line is branching off of another line that goes toward the front of the car.
Scott
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The vacuum line from the brake booster goes directly to the carb there is a black devise which looks like a old type gas filter in the line which permits air flow either way. Is this a check valve which should prevent vacuum release back to the carb? Maybe this is my problem
Le Mans Master
Joined: Mar 2008
Posts: 5,948
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From: Oxford MA-----You just lost the game!!!!
The vacuum line from the brake booster goes directly to the carb there is a black devise which looks like a old type gas filter in the line which permits air flow either way. Is this a check valve which should prevent vacuum release back to the carb? Maybe this is my problem
I'm pretty sure that's just an air filter. So, your headlights are a separate issue, there is no connection.
Scott
Thread Starter
Intermediate
Joined: Apr 2005
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1980 corvette brake problems
let me finalize my blog. I brought to restoration shop. Brakes needed to be power bled & 2 calibrators started leaking,they installed all new & new brake lines which were 5 y/o & said I needed a new master cylinder again ,the 4th. brakes are ok now after spending 1,700 plus dollars
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