brakes
03-11-2018, 05:51 PM
#1
3rd Gear
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brakes
I put new brakes on my 71 corvette, master cylinder, lines, metering valve. calipers. rotors. and power assist. I bench blead the master cylinder, and each caliper, and have pretty good pedal with the car off, once i start it up the brake pedal is very soft. Any ideas where i went wrong?
03-11-2018, 06:08 PM
#2
Melting Slicks
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Pretty good pedal with no assist . I just went through a car re-bleed ,the pedal with the engine off has to be rock hard .
If there is no fluid leaks , it sounds like you still have air in the system .
What method did you use to bleed the m/c and then the whole car ?
If there is no fluid leaks , it sounds like you still have air in the system .
What method did you use to bleed the m/c and then the whole car ?
Last edited by bazza77; 03-11-2018 at 06:10 PM.
03-11-2018, 08:53 PM
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Nam Labrat
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03-12-2018, 12:40 AM
#7
Drifting
03-12-2018, 01:17 AM
#8
3rd Gear
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Brakes
Bled the MC in a vice and pumped until all air was gone, standard bleed at wheel cylinders, with a clear hose on bleeder, pump up, hold pressure, open bleeder and close before the pedal bottoms out. have bled them twice, no air detected. Fluid seemed a little dark coming from the wheel cylinders. Have pretty good pedal not running, changing fuel pump so it will be a little while before I can run it again.
thanks for all the ideas, I’ll keep you posted
thanks for all the ideas, I’ll keep you posted
03-12-2018, 06:22 AM
#9
Yep, Stephanie is mine. Had her pump two/three time, nothing coming out of the bleeder. Hmm, that's strange. Could the MC be empty? Nope, Me, "honey are you sure you're pressing the brake pedal", Stephanie, Oh, sorry I was pressing the gas pedal. Didn't get mad, had a good laugh and then we bled brakes.
03-12-2018, 11:30 AM
#10
Melting Slicks
Keep bleeding them until only new clear fluid comes out all the bleeds, and also make sure you use all the bleeds on each caliper (not just the outside ones).
03-12-2018, 11:39 AM
#11
Dementer sole survivor
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2020 C3 of the Year Finalist - Modified
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motiv power bleeder is the name of it. If you borrow one, you have to use clamps to hold the plate on the master cylinder. Very easy to use and simple as well. Just put fluid in the reservoir and pump it up, climb under the car and open and close all the bleed valves. Just keep an eye on the fluid and clean it good when your done. No drama at all.
before you start again, pump up the brakes then start your car, the pedal should move when you get vacuum. if not there is an issue there as well, but roght now t still sounds like air in the system. Are you going in the correct order.
rear passenger, drivers rear, front passenger, drivers side. I believe you do inner then outer on each of the rear calipers
before you start again, pump up the brakes then start your car, the pedal should move when you get vacuum. if not there is an issue there as well, but roght now t still sounds like air in the system. Are you going in the correct order.
rear passenger, drivers rear, front passenger, drivers side. I believe you do inner then outer on each of the rear calipers
03-12-2018, 12:00 PM
#12
Safety Car
motiv power bleeder is the name of it. If you borrow one, you have to use clamps to hold the plate on the master cylinder. Very easy to use and simple as well. Just put fluid in the reservoir and pump it up, climb under the car and open and close all the bleed valves. Just keep an eye on the fluid and clean it good when your done. No drama at all.
before you start again, pump up the brakes then start your car, the pedal should move when you get vacuum. if not there is an issue there as well, but roght now t still sounds like air in the system. Are you going in the correct order.
rear passenger, drivers rear, front passenger, drivers side. I believe you do inner then outer on each of the rear calipers
before you start again, pump up the brakes then start your car, the pedal should move when you get vacuum. if not there is an issue there as well, but roght now t still sounds like air in the system. Are you going in the correct order.
rear passenger, drivers rear, front passenger, drivers side. I believe you do inner then outer on each of the rear calipers
03-12-2018, 02:27 PM
#13
Melting Slicks
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I had trouble getting a solid pedal , so I used a rubber mallet and gently tapped each calliper and the flexi hose connections, which seemed to dislodge quite a lot of air that I couldn't get out before .
in total and with driving the car in the middle of the saga I used 3 litres of fluid and went around the car 7 times before I was happy with it .
in total and with driving the car in the middle of the saga I used 3 litres of fluid and went around the car 7 times before I was happy with it .
04-23-2020, 07:18 PM
#16
Sounds like the master cylinder to me. Pull the lines from the master cylinder. Screw plugs into the master cylinder. Start the car. Pedal should be rock solid. If not the master is bad.
Last edited by Tbair64; 04-23-2020 at 07:19 PM.
04-23-2020, 07:39 PM
#17
Le Mans Master
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Likely fixed by now. See date.
04-24-2020, 11:46 AM
#19
Melting Slicks
Ronarndt! LOLZ.
Worse happened to me...
After all the explanations of down-hold-stay-ok-up!
I'm basically under the car....
Okay! Honey DOWN! (nothing happens)
UP! NOW DOWN AGAIN...nothing! WTF.
I get up from under the car to see what she is doing.
HONEY, THE BRAKE PEDAL IS THE MIDDLE ONE! ARRRGH!
VERY IMPORTANT GUYS! DO NOT DEPRESS THE BRAKE PEDAL TO THE FLOOR! PUT A WOOD 2X4" UNDER THE BRAKE PEDAL TO PREVENT THIS!
REASON IS! THE M/C SWEEPS THE PISTONS ABOUT 3/4 THE WAY TO THE FLOOR ON FULL BRAKING....WHEN YOU GO PAST THAT, YOU 'SWEEP' THE PISTONS AND CUPS INTO THE UN-USED PORTION OF THE M/'C... THEREBY RUINING THE CUPS/SEALS WITH ROUGH BORES AND DEBRIS.
DON'T DO IT!
UNKAHAL
Worse happened to me...
After all the explanations of down-hold-stay-ok-up!
I'm basically under the car....
Okay! Honey DOWN! (nothing happens)
UP! NOW DOWN AGAIN...nothing! WTF.
I get up from under the car to see what she is doing.
HONEY, THE BRAKE PEDAL IS THE MIDDLE ONE! ARRRGH!
VERY IMPORTANT GUYS! DO NOT DEPRESS THE BRAKE PEDAL TO THE FLOOR! PUT A WOOD 2X4" UNDER THE BRAKE PEDAL TO PREVENT THIS!
REASON IS! THE M/C SWEEPS THE PISTONS ABOUT 3/4 THE WAY TO THE FLOOR ON FULL BRAKING....WHEN YOU GO PAST THAT, YOU 'SWEEP' THE PISTONS AND CUPS INTO THE UN-USED PORTION OF THE M/'C... THEREBY RUINING THE CUPS/SEALS WITH ROUGH BORES AND DEBRIS.
DON'T DO IT!
UNKAHAL
04-24-2020, 01:30 PM
#20
Team Owner
Just for discussion>>>>
This thread does not consider the condition of the rubber jumper hoses going to each caliper. After years of use, these items go bad ON THE INSIDE. They can gum up so that brake fluid will not fully release pressure on the pads, causing excessive heating and possibly causing fire (burning tire!); or it can 'balloon' when under firm braking pressure making for a soft pedal that will NOT go away. These hoses are the most dangerous, OVERLOOKED item on a car being restored/refurbished.
This thread does not consider the condition of the rubber jumper hoses going to each caliper. After years of use, these items go bad ON THE INSIDE. They can gum up so that brake fluid will not fully release pressure on the pads, causing excessive heating and possibly causing fire (burning tire!); or it can 'balloon' when under firm braking pressure making for a soft pedal that will NOT go away. These hoses are the most dangerous, OVERLOOKED item on a car being restored/refurbished.