Brake Issue on Re-assembly
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Joined: Oct 2013
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From: Visalia CA
Brake Issue on Re-assembly
OK, the brakes worked fine on my '74 C3 when I drove it into my garage. Had to disconnect the rear brakes & remove the rotors so I could work on another another project. When I got done with the project, I put it all back together, bled both back lines (did fronts as well), and now my brake pedal goes to the floor. Re-checked everything. Even re-bled them - no air bubbles, steady flow, kept master cylinder full . . . but now have no pedal.
Any thoughts?
Thanks in advance.
Wayne
P.S. I noticed there are bleeder valves on each reservoir of the master cylinder. Do those need to get bled? Why are they there?
Any thoughts?
Thanks in advance.
Wayne
P.S. I noticed there are bleeder valves on each reservoir of the master cylinder. Do those need to get bled? Why are they there?
Burning Brakes
Joined: Sep 2010
Posts: 822
Likes: 82
From: Columbus OH
Hi Wayne,
A couple of questions to help you get some educated answers back.
Power or Manual Brakes?
Did you disconnect the calipers or any brake lines when you changed out the rotors?
What is your process for "bleeding" the brakes?
Did the master ever go empty?
Do you know how old the rubber hoses are?
A couple of questions to help you get some educated answers back.
Power or Manual Brakes?
Did you disconnect the calipers or any brake lines when you changed out the rotors?
What is your process for "bleeding" the brakes?
Did the master ever go empty?
Do you know how old the rubber hoses are?
Thread Starter
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Joined: Oct 2013
Posts: 76
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From: Visalia CA
SEE ANSWERS BELOW:
A couple of questions to help you get some educated answers back.
Power or Manual Brakes? POWER
Did you disconnect the calipers or any brake lines when you changed out the rotors? YES, TOOK CALIPERS WERE OFF THE ROTORS AND DISCONNECTED FROM SYSTEM AT RUBBER HOSE.
What is your process for "bleeding" the brakes? INITIALLY, I WAS USING A HAND VACUUM PUMP WITH AN INLINE CANISTER TO COLLECT FLUID. WHEN THE PROBLEM STILL PERSISTED, I BROUGHT MY WIFE OUT TO ASSIST FROM THE COCKPIT. AS SHE WOULD HOLD THE PEDAL DOWN, I WOULD OPEN THE BLEEDER VALVE & CLOSE IT BEFORE SHE WOULD LET THE PEDAL UP. WE REPEATED THAT PROCESS UMPTEEN TIMES, UNTIL I WAS CERTAIN THERE WAS NO AIR BUBBLES AND THE FLUID WAS STEADY.
Did the master ever go empty? YES, AND RE-BLED LINES FOLLOWING.
Do you know how old the rubber hoses are? PRETTY OLD, BUT THEY DID NOT APPEAR TO BE LEAKING.
A couple of questions to help you get some educated answers back.
Power or Manual Brakes? POWER
Did you disconnect the calipers or any brake lines when you changed out the rotors? YES, TOOK CALIPERS WERE OFF THE ROTORS AND DISCONNECTED FROM SYSTEM AT RUBBER HOSE.
What is your process for "bleeding" the brakes? INITIALLY, I WAS USING A HAND VACUUM PUMP WITH AN INLINE CANISTER TO COLLECT FLUID. WHEN THE PROBLEM STILL PERSISTED, I BROUGHT MY WIFE OUT TO ASSIST FROM THE COCKPIT. AS SHE WOULD HOLD THE PEDAL DOWN, I WOULD OPEN THE BLEEDER VALVE & CLOSE IT BEFORE SHE WOULD LET THE PEDAL UP. WE REPEATED THAT PROCESS UMPTEEN TIMES, UNTIL I WAS CERTAIN THERE WAS NO AIR BUBBLES AND THE FLUID WAS STEADY.
Did the master ever go empty? YES, AND RE-BLED LINES FOLLOWING.
Do you know how old the rubber hoses are? PRETTY OLD, BUT THEY DID NOT APPEAR TO BE LEAKING.
Le Mans Master
Joined: Jan 2003
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From: Tuttle OK
Cruise-In VIII Veteran
Melting Slicks
Joined: May 2011
Posts: 2,753
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From: Springfield Missouri
in what order did you bleed the brakes(front right first etc.) did you open up the correct bleeder on the caliper? any air coming out?? The master has to have all the air out to properly bleed the rest. M/c could of gone bad(probably not, but maybe). have to bleed in proper sequence thou!
Melting Slicks
Joined: Jul 2010
Posts: 2,503
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From: McGrady NC
St. Jude Donor '15-'16
Lots of opinions and success stories on how to properly bleed the brakes on a Corvette. Just search for "bleed brakes". I do it using the gravity method and start at the right rear, left rear, right front, left front doing one at a time. Keep the MC full at all times. Never had much luck bleeding the MC on the car but I see that you could. Sometimes when installing brand new calipers I would ask for assistance from the co-pilot to pump the brakes just to speed up the process. Otherwise, I always have good luck with the gravity method.
I also use a rubber mallet to loosen any residual bubbles in the calipers as I go. A few taps just to break the air bubbles free is all you need.
I also use a rubber mallet to loosen any residual bubbles in the calipers as I go. A few taps just to break the air bubbles free is all you need.
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Thread Starter
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Joined: Oct 2013
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From: Visalia CA
Anyway thank you very much for mentioning what most probably assumed that I knew.
Having said that, I will go back to square-on on the bleeding. If I were going to bleed the master cylinder too (bleeders ARE on each reservoir), I presume I should do that first??
Thanks again to those who responded. It is much appreciated.
throw that Haynes book away!!!! NOT GOOD ON CORVETTES. Questions like brake bleeding can be answered here and much correctly
Drifting
Joined: May 2012
Posts: 1,353
Likes: 44
From: Calgary Alberta
"I just reviewed it again, and Haynes says that 78-82 have double-bleeders in the rear but 68-77 do not. Can anyone either confirm or deny that? That's confusing since mine is a 74".
That's incorrect. They all have two bleeder screws on the rear calipers, an inner and an outer, both at the front of the caliper. Bleed inner first, then outer, starting at the passenger side rear, then driver side rear, then on to the front (where you go passenger side first, then driver). That's from the GM manual, paraphrased, and it has always worked for me.
That's incorrect. They all have two bleeder screws on the rear calipers, an inner and an outer, both at the front of the caliper. Bleed inner first, then outer, starting at the passenger side rear, then driver side rear, then on to the front (where you go passenger side first, then driver). That's from the GM manual, paraphrased, and it has always worked for me.
Thread Starter
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Joined: Oct 2013
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From: Visalia CA
Thread Starter
Advanced
Joined: Oct 2013
Posts: 76
Likes: 0
From: Visalia CA
"I just reviewed it again, and Haynes says that 78-82 have double-bleeders in the rear but 68-77 do not. Can anyone either confirm or deny that? That's confusing since mine is a 74".
That's incorrect. They all have two bleeder screws on the rear calipers, an inner and an outer, both at the front of the caliper. Bleed inner first, then outer, starting at the passenger side rear, then driver side rear, then on to the front (where you go passenger side first, then driver). That's from the GM manual, paraphrased, and it has always worked for me.
That's incorrect. They all have two bleeder screws on the rear calipers, an inner and an outer, both at the front of the caliper. Bleed inner first, then outer, starting at the passenger side rear, then driver side rear, then on to the front (where you go passenger side first, then driver). That's from the GM manual, paraphrased, and it has always worked for me.
Melting Slicks
Joined: Jul 2001
Posts: 2,609
Likes: 12
From: Massapequa Park NY
A good friend of mine swears the proper order for Corvette as stated in the service manual is:LR inner
LR outer
RR inner
RR outer
FL
FR
I haven't found it in there but he claims he has bled the brakes on many Vettes in this order & gotten a good pedal in one round. He has owned and built many mid years & C3's and is an NCRS mid year judge. So, another opinion, for what it's worth $.02
Good luck
Jim
Safety Car
Joined: Aug 2001
Posts: 4,883
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From: North Easton Mass
If the master cylinder reservior emptied you will have to bench bleed the master cylinder or you will never get pedal pressure. You can do it with the cylinder on the car if you park on a slight incline and jack the back of the car up until the top of the master cylinder is level. Disconnect the brake lines and do a normal bench bleed and you should get better results when you bleed the rear calipers. A little less effort than taking the cylinder off.
If you haven't done it already this would be a good time to replace brake hoses.
Rick B.
If you haven't done it already this would be a good time to replace brake hoses.
Rick B.
Race Director
Joined: Apr 2007
Posts: 11,150
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From: South Western Ontario
Not bleeding the inner half of the caliper is likely what the issue is.
When we did Dad's car we tore off everything but the main steel lines before blowing them out and replacing everything new. Then filled it and let it gravity bleed before a little pedal pumping and bleeding. The brakes work great. So, I'd think you are fine with the vacuum bleeding re-filling the master.
When we did Dad's car we tore off everything but the main steel lines before blowing them out and replacing everything new. Then filled it and let it gravity bleed before a little pedal pumping and bleeding. The brakes work great. So, I'd think you are fine with the vacuum bleeding re-filling the master.
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Joined: Oct 2013
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From: Visalia CA
Not to sound like a total dummy here, but I have two questions:
1. What is the specific process for bench bleeding a corvette master cylinder. Never done it.
2. Everyone keeps referring to "gravity bleeding". Never heard of that either. What is the specific procedure. I've typically always just used a 2nd person to strategically depress/hold the brake pedal while I opened/closed bleeder valves.
Thanks for everyone's input.
Wayne
1. What is the specific process for bench bleeding a corvette master cylinder. Never done it.
2. Everyone keeps referring to "gravity bleeding". Never heard of that either. What is the specific procedure. I've typically always just used a 2nd person to strategically depress/hold the brake pedal while I opened/closed bleeder valves.
Thanks for everyone's input.
Wayne
Race Director
Joined: Apr 2007
Posts: 11,150
Likes: 890
From: South Western Ontario
To gravity bleed just take the cover off the master and open the bleeder and wait until fluid starts running out.
Did you try bleeding all 4 screws on the rear calipers yet? If you've been able to pump fluid through the master by bleeding it then I can't see you needing to bench bleed. Typically, you can't get any fluid flow when you need to bench bleed.
Did you try bleeding all 4 screws on the rear calipers yet? If you've been able to pump fluid through the master by bleeding it then I can't see you needing to bench bleed. Typically, you can't get any fluid flow when you need to bench bleed.