Brake Issues
#21
10-03-2008, 10:44 AM
RE: Brake Issues
Advance Auto online... 29.99-99.99 master cylinders... all the difference in the world!
http://www.partsamerica.com/productl...30&PTSet=A
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http://www.partsamerica.com/productl...30&PTSet=A
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#22
10-03-2008, 12:04 PM
RE: Power Booster.
Why is the pedal harder to push when there is no vacuum?
The booster has 2 chambers seperated by a diaphragm. When the motor is running both chambers get vacuum. When you step on the brake pedal you allow atmospheric air pressure to enter the rear chamber, the vacuum is greater than the AAP and pulls the mechanical parts foward and the car slows and stops.
What if the motor stalls?
The check valve will hold some vacuum. Each time you pump the brakes you use up some of the reserve vacuum. Once all the vacuum is gone you can still stop the car with the mechanical parts in the booster. There are springs in the booster that must be compressed by extra pressure on the brake pedal, and thats why the pedal seems harder when there is no vacuum.
An easy test to see if a power booster is working:
With the motor off pump the brake pedal 5 or 6 times to bleed off all vacuum. Release the brake pedal than apply light pressure. Than hold that light pressure and start the motor, if the booster is working the pedal will go down a little. PG.
The booster has 2 chambers seperated by a diaphragm. When the motor is running both chambers get vacuum. When you step on the brake pedal you allow atmospheric air pressure to enter the rear chamber, the vacuum is greater than the AAP and pulls the mechanical parts foward and the car slows and stops.
What if the motor stalls?
The check valve will hold some vacuum. Each time you pump the brakes you use up some of the reserve vacuum. Once all the vacuum is gone you can still stop the car with the mechanical parts in the booster. There are springs in the booster that must be compressed by extra pressure on the brake pedal, and thats why the pedal seems harder when there is no vacuum.
An easy test to see if a power booster is working:
With the motor off pump the brake pedal 5 or 6 times to bleed off all vacuum. Release the brake pedal than apply light pressure. Than hold that light pressure and start the motor, if the booster is working the pedal will go down a little. PG.
#23
10-03-2008, 04:02 PM
RE: Brake Issues
I had a problem very similar to this one a few years back.
Went nuts trying to figure it out.
Guess what, it was a bad master cylinder.
If your power booster is shot it will not effect your pedal, only make it harder to stop.
I will bet a lunch on the master cylinder!
Went nuts trying to figure it out.
Guess what, it was a bad master cylinder.
If your power booster is shot it will not effect your pedal, only make it harder to stop.
I will bet a lunch on the master cylinder!
#24
10-03-2008, 05:19 PM
RE: Brake Issues
To make it easier... fill the master cylinder before you install it. It will cut down on the time it takes to bleed it out, and the amount of juice you waste. DO NOT use the stuff that comes out... even if it looks clean!
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#25
10-29-2008, 06:33 PM
RE: Brake Issues
Does anyone know the bleeding sequence for a 1977 corvette? Im having to pump my brakes 4-5 times before they start working.
#27
01-11-2012, 11:22 AM
New MC..same problem
On my '77..I changed the Master Cylinder...bled brakes and had pretty good pedal. Drove 25 miles on freeway...stepped on brakes on off-ramp..pedal went way down and "Brake" LIGHT CAME ON AGAIN. IDEAS? THANKS,. RACERMAN
#28
01-27-2012, 07:02 PM
Racerman, I would bleed all four corners again, you may have still had some air in the lines or the system is leaking. If your sure it's air-free and you see no fluid leaking then I would point to the new master cylinder again.
#30
02-12-2012, 01:53 AM
Brake pedal is traveling pretty far to apply the brakes. Warning light came on, so I swapped pads, checked fluid level. Problem still persisted so I bled the brake lines. Got some air from the left front, went through the cycle a little over a dozen times on this caliper so I assume I got most the air out, brake pedal is better but still requires significant travel to apply brakes. Brake system stops short just fine if you apply enough travel, and brake warning light went away after bleeding. Curious to see if anyone has any suggestions? Should I try bleeding again? Is there something else that could be causing the problem or causing the air intake. Have not noticed decrease in performance or travel since bleeding the lines. But still just too much travel. Rotors did not seem in too bad of shape but I haven't measured yet. Ran and pumped brakes significantly and did not observe and leaks at the calipers or along any of the lines. Not sure on the condition of the calipers but appeared in good shape and car brakes evenly no pulsating, no pulls. Any suggestions would be greatly appreciated. thanks in advance for any help.
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