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  #1  
Old 10-18-2006, 03:21 PM
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Brakes locked up?

I recently replaced the master cylinder and the other day the brakes locked up and were smoking badly. Is it possibly I need to replace the rotors?

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  #2  
Old 10-18-2006, 04:52 PM
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I had a similar problem a few months ago with one exception. My right front brake locked up, smoking. I had to replace the master cylinder and both front calipers and rotors. The rotor siezed up and they have to be replaced in pairs....ouch!
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  #3  
Old 10-18-2006, 05:18 PM
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Quote:
Originally Posted by miketaco View Post
I recently replaced the master cylinder and the other day the brakes locked up and were smoking badly. Is it possibly I need to replace the rotors?
The only time you really need to replace rotors is when warping occurs or there is to much wear. If there is no warping (wobbles when braking) dont worry about it.
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Old 10-18-2006, 06:50 PM
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You probably don't have enough freeplay between the brake pushrod and the master cylinder piston. What is happening is that the master cyl piston isn't coming all the way back to the fluid pressure release port. The pushrod that protrudes from the power brake booster is adjustable. If needed, screw it in some to shorten it. Check first that the brake pedal is returning back ALL the way.
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Old 10-18-2006, 09:13 PM
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mike,

I second what winmutt says.

P E H
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  #6  
Old 10-19-2006, 07:52 AM
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Quote:
Originally Posted by Motorhead View Post
You probably don't have enough freeplay between the brake pushrod and the master cylinder piston. What is happening is that the master cyl piston isn't coming all the way back to the fluid pressure release port. The pushrod that protrudes from the power brake booster is adjustable. If needed, screw it in some to shorten it. Check first that the brake pedal is returning back ALL the way.
Interesting. My brakes drag a bit, I wonder if this is why. (all of my drivetrain look brand new, i love this car).
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  #7  
Old 10-19-2006, 08:17 AM
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Clint,

ANd why do the rotors and calipers have to be replaced in pairs?

P E H
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  #8  
Old 10-19-2006, 08:31 AM
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Brake Line Blockage or Frozen Piston

Quote:
Originally Posted by winmutt View Post
Interesting. My brakes drag a bit, I wonder if this is why. (all of my drivetrain look brand new, i love this car).
It could also be blockage in the flexible brake lines that go to each wheel. They won't let the brake fluid back out of the caliper so the pads still have pressure against the rotor, which heats everything up and can cook the caliper. Feel the wheels after you have been out driving. If they are hot, that is where the problem is.

You could also have caliper pistons that are frozen in their bore. When is the last time you changed the pads? Did all the pistons push back into their bores without too much resistance?
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Old 10-19-2006, 11:08 AM
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Sometimes a ring of rust and gunk forms around the caliper pistons, I've had 2 friends w/ Dodge pickups this has happened to. Simply popping off the caliper and sanding down the piston freed them. Well, not so simple to get the caliper off since it's hanging on for dear life, but you get the picture.
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  #10  
Old 10-19-2006, 11:51 AM
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If this happens after heavy braking, then it could be that the fluid is contaminated and starts to boil in the caliper. It is rare, but it is a possibility. If the brake fluid is DOT3, then it is hygroscopic in nature, and if it has absorbed a lot of water over time, then the boiling point will be reduced. I don't believe that calipers need to be replaced in pairs, but that seems to be the current mode of thinking. I believe that the logic is that if one goes bad, that the other isn't far behind. When doing brake service, the best thing is to do it well, because unlike bad engine maintenance that will leave you stranded on the side of the road, bad brakes might leave you in the middle of a tree... Do it once..... do it right.
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  #11  
Old 10-19-2006, 01:35 PM
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Quote:
Originally Posted by riethoven View Post
It could also be blockage in the flexible brake lines that go to each wheel. They won't let the brake fluid back out of the caliper so the pads still have pressure against the rotor, which heats everything up and can cook the caliper. Feel the wheels after you have been out driving. If they are hot, that is where the problem is.

You could also have caliper pistons that are frozen in their bore. When is the last time you changed the pads? Did all the pistons push back into their bores without too much resistance?
Like I said the drivetrain on my car is practically new. I doubt its anything other than this adjustment.
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  #12  
Old 10-19-2006, 01:37 PM
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Quote:
Originally Posted by winmutt View Post
Like I said the drivetrain on my car is practically new. I doubt its anything other than this adjustment.
OOPS. I meant to quote miketaco.

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