Brake problems
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Brake problems
First off, this is my first car that's had 1/2 shafts and a posi, so I don't know what a "normal" condition is.
problem 1: replaced old leaking master cylinder. Bled brakes throughly. After a day or two, the pedal goes down. I have to pump them up. Is this normal for a non-power braked car? If not, where should I look? Once pumped up, they stop fine. I see no leaks on my garage floor, either.
problem 2: I think I have a dragging rear brake. I loosened up the parking brake cable considerably, to eliminate it as a cause. When the car is coasting to a stop in neutral, it feels like it's dragging, as it stops rather quickly the last few feet. I put the car on jack stands and rotated the tires by hand. They don't turn that easily. I'm not sure if this is the posi causing this or a brake. I have nothing to judge it by. Thanks
problem 1: replaced old leaking master cylinder. Bled brakes throughly. After a day or two, the pedal goes down. I have to pump them up. Is this normal for a non-power braked car? If not, where should I look? Once pumped up, they stop fine. I see no leaks on my garage floor, either.
problem 2: I think I have a dragging rear brake. I loosened up the parking brake cable considerably, to eliminate it as a cause. When the car is coasting to a stop in neutral, it feels like it's dragging, as it stops rather quickly the last few feet. I put the car on jack stands and rotated the tires by hand. They don't turn that easily. I'm not sure if this is the posi causing this or a brake. I have nothing to judge it by. Thanks
Race Director
Joined: Aug 2004
Posts: 10,628
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From: Duvall, WA
Problem 1: this isn't normal. You may have excess runout that is a symptom of a rotor that isn't flat or a worn bearing. Take a dial indicator and check your runout.
Problem 2: Could be a brake line that is collapsing and not letting hydraulic fluid release from the caliper.
Problem 2: Could be a brake line that is collapsing and not letting hydraulic fluid release from the caliper.
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Thanks for the replies. Update - I just took it out for another test-run (it's supposed to ice up tonight, so I HAD TO!). I noticed when I backed out of the garage, it rolled easy in neutral. However, after driving about 30 minutes, it's definitely dragging.
I don't own a dial gauge, much less ever used one, so I guess I'll either just have to replace everything (diagnostics for dummies), or pay a shop to do it, which I hate having other people work on my car.
I'm pulling the motor next week and it will be down for awhile. I'll take a look at the rotor/caliper while the block and heads are being worked on.
I don't own a dial gauge, much less ever used one, so I guess I'll either just have to replace everything (diagnostics for dummies), or pay a shop to do it, which I hate having other people work on my car.
I'm pulling the motor next week and it will be down for awhile. I'll take a look at the rotor/caliper while the block and heads are being worked on.
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Originally Posted by stingraymaniac
Did you bench bleed the master before you got it in the car?
there can be some rotor run out that is causing this,the calipers suck in alittle air if the rotors are bad...
there can be some rotor run out that is causing this,the calipers suck in alittle air if the rotors are bad...
Yes I did bench bleed it thoroughly. I bled them for a long time too, until I was sure there was clean, bubble-free fluid coming out.
So what you're saying is, if the rotors are too thin, the pistons extend beyond where they should? I love working on my car, but after just driving it, I really like driving it! I've only had it a few months, and I just had Lars rebuild the carb and dist, so it's a rocket! It's going to be painful not driving it starting next week, when I pull the motor out...
Instructor
Joined: May 2003
Posts: 220
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From: Hilton Va
Does your master cylinder rod have an adjustment on the end of it where it goes into the master cylinder ? If so, it sounds like it may be adjusted out too far. The reason I say this is because, you said that at the garage it rolled freely,but after 30 minutes of driving it felt like it was dragging. The rod being out of adjustment will cause this exact problem.
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Originally Posted by carhound
Does your master cylinder rod have an adjustment on the end of it where it goes into the master cylinder ? If so, it sounds like it may be adjusted out too far. The reason I say this is because, you said that at the garage it rolled freely,but after 30 minutes of driving it felt like it was dragging. The rod being out of adjustment will cause this exact problem.
I wonder what the adjustment should be? I guess I'll try backing it out 1/8" at a time and see.
Mark
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Le Mans Master
Joined: Jan 2006
Posts: 9,192
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From: Boca Raton Florida
I doubt they adjusted the rod during the change. Sounds more like there is a dragging rotor, it is probly heating up the caliper and expanding the bubbled still in the line push the pads out.
Le Mans Master
Joined: Jun 2003
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From: Umeå Sweden
Originally Posted by AirTrafficController
Yes I did bench bleed it thoroughly. I bled them for a long time too, until I was sure there was clean, bubble-free fluid coming out.
So what you're saying is, if the rotors are too thin, the pistons extend beyond where they should? I love working on my car, but after just driving it, I really like driving it! I've only had it a few months, and I just had Lars rebuild the carb and dist, so it's a rocket! It's going to be painful not driving it starting next week, when I pull the motor out...
So what you're saying is, if the rotors are too thin, the pistons extend beyond where they should? I love working on my car, but after just driving it, I really like driving it! I've only had it a few months, and I just had Lars rebuild the carb and dist, so it's a rocket! It's going to be painful not driving it starting next week, when I pull the motor out...