Brake pedal problems
Thread Starter
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Brake pedal problems
I just installed a new master cylinder again(the first one was bad). When I step on the brake pedal it feels like it should, until it gets about halfway down, then it won't go down anymore. Feels like it is accually hitting something. Any ideas?
Aaron
Aaron
Burning Brakes
Joined: Mar 2002
Posts: 803
Likes: 0
From: South San Francisco CA
Re: Brake pedal problems (AV76)
Sounds like the pads are squishing against the rotors as much as they can. How can the pedal go down anymore? Maybe it's just fixed....hmmmm???? Mind does the exact same thing.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Brake pedal problems (fontking1a)
I had a thought on this. Sorry to reply to my own message, possibly with the answer to my question :D . Could it be that the rod that pushes into the mastercylinder that moves when you push the brake pedal needs to be adjusted. Could the piston in the master cylinder be bottoming out because the rod from the brake pedal is too long? Just trying to throw some ideas around. Does any of that make sense?
Any comments, related or unrelated, would be appreciated,
Aaron
Any comments, related or unrelated, would be appreciated,
Aaron
Melting Slicks
Joined: Nov 2000
Posts: 3,336
Likes: 4
From: Springfield MA
Re: Brake pedal problems (Duke94)
Whoa there.... If you intalled a new MC, was it the same "exact" size? The reason that I ask is because I had a similar problem earlier.
The pushrod from the booster was extended WAY too far for the new master cylinder. It was actually pushing against the end of the cylinder with the pedal fully depressed. I didn't notice much because the brakes didn't work at all. Then I replaced everything including the booster. That is when I realized that the pushrod was WAY out of whack. With good lines, bled etc... the pushrod should not need to go all the way to the back of the master cylinder because there should be enough hydraulic pressure to stop the pedal before then. If not, I'd say check the length of the rod before slamming that pedal down and destroying the new master cylinder.
Trust me on this... been there done that. :):D
The pushrod from the booster was extended WAY too far for the new master cylinder. It was actually pushing against the end of the cylinder with the pedal fully depressed. I didn't notice much because the brakes didn't work at all. Then I replaced everything including the booster. That is when I realized that the pushrod was WAY out of whack. With good lines, bled etc... the pushrod should not need to go all the way to the back of the master cylinder because there should be enough hydraulic pressure to stop the pedal before then. If not, I'd say check the length of the rod before slamming that pedal down and destroying the new master cylinder.
Trust me on this... been there done that. :):D
Thread Starter
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Brake pedal problems (phoenix)
The mastercylinder appears to be the same size. I shortened the pushrod from the booster. When I push down the pedal and crack a bleeder, the pedal now goes almost to the floor. When I push down on the pedal when I'm driving, the pedal is really hard to push and the car is reluctant to stop. It takes a lot of effort. The pedal goes about half way down If I push very hard. Does this sound like the power booster? Any ideas on what to check? Could it be another bad master cylinder?
Thanks for the help,
Aaron
[Modified by AV76, 4:41 PM 9/27/2002]
Thanks for the help,
Aaron
[Modified by AV76, 4:41 PM 9/27/2002]
Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Re: Brake pedal problems (AV76)
Could be the booster. Disconnect and plug the vacuum line (at the engine) to the booster and drive it again (very carefully). Does the pedal and braking feel the same as it did connected? If so, the booster is kaput.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Brake pedal problems (Duke94)
I drove the car with the power booster unplugged and the car was harder to stop than with it plugged in. This seems weird, could it be another bad master cylinder?
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Le Mans Master
Joined: Mar 2001
Posts: 6,640
Likes: 287
From: Ann Arbor Michigan
Re: Brake pedal problems (AV76)
Are you sure you have the correct diameter M/C? Book says 1" for manual and 1 1/8" for power (67-76). 1" for all on 77-82. Don't remember what year you had.
Thread Starter
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Brake pedal problems (Duke94)
I have a 76, so that would definitly be something to check. I assume that is the diameter of the piston that the pushrod presses on? I hope it is something that simple, but at the same time I would hate to waste this much time on something that simple. I'll check that and, if it doesn't help, my mechanic will take a look at the car on Saturday.
Thanks for the advise, :cheers:
Aaron
Thanks for the advise, :cheers:
Aaron