How do I troubleshoot brakes?
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Melting Slicks
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From: What did the 5 fingers say to the face? SLAP!!
How do I troubleshoot brakes?
So I get in the car this morning and the first thing I notice is the brake pedal is rock hard. I drove it around the block to see if it would get better, but it didn't. When I pulled back in the garage it smelled like the brakes were burning. I thought maybe one of the calipers was stuck. I popped the hood to get a closer look and smoke rolled out from under it. I think it was more on the passenger side, but I couldn't really tell because it happened too quick. I jacked the front end up to see if the wheels would turn freely. They both did, although the passenger side was definately dragging more than the drivers side. But it still turned somewhat easily. So now I'm thinking it's either the master cylinder or the booster. I replaced the booster 2 years ago, and you could hear a loud hiss when the old one went out. I don't hear any hissing this time. How do I troubleshoot this short of throwing parts at it? Any and all help is appreciated. Thanks
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by flyersfan1088
So I get in the car this morning and the first thing I notice is the brake pedal is rock hard. I drove it around the block to see if it would get better, but it didn't. When I pulled back in the garage it smelled like the brakes were burning. I thought maybe one of the calipers was stuck. I popped the hood to get a closer look and smoke rolled out from under it. I think it was more on the passenger side, but I couldn't really tell because it happened too quick. I jacked the front end up to see if the wheels would turn freely. They both did, although the passenger side was definately dragging more than the drivers side. But it still turned somewhat easily. So now I'm thinking it's either the master cylinder or the booster. I replaced the booster 2 years ago, and you could hear a loud hiss when the old one went out. I don't hear any hissing this time. How do I troubleshoot this short of throwing parts at it? Any and all help is appreciated. Thanks
Last edited by Corvette Kid; Mar 23, 2005 at 06:27 PM.
Race Director
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Originally Posted by flyersfan1088
They both did, although the passenger side was definately dragging more than the drivers side. But it still turned somewhat easily.
Pop the line loose at the passenger caliper. I bet the wheel will turn easier.
When you get a new line, change both sides.
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Melting Slicks
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From: What did the 5 fingers say to the face? SLAP!!
Originally Posted by Corvette Kid NC
Has anything been replaced recently?
No
Now, crack the bleeder screws to relieve excess pressure and see if the pedal returns to a normal feel. Take it for a short drive if necessary, the problem will probably return. The pedal may just return to the "hard" feel with just a few pumps. If it does, loosen the master cylinder mounting bolts to gain clearance and free travel, relieve the pressure with the bleeders again and try again. If this helps, something is not allowing the cylinder to retract. I've never seen a cylinder itself cause this but I won't rule that out. This should get you started.
No
Now, crack the bleeder screws to relieve excess pressure and see if the pedal returns to a normal feel. Take it for a short drive if necessary, the problem will probably return. The pedal may just return to the "hard" feel with just a few pumps. If it does, loosen the master cylinder mounting bolts to gain clearance and free travel, relieve the pressure with the bleeders again and try again. If this helps, something is not allowing the cylinder to retract. I've never seen a cylinder itself cause this but I won't rule that out. This should get you started.
I tried just bleeding and the pedal was somewhat softer for one pump, than it got hard again. Then I tried loosening the MC and the pedal got softer again. What should I look at next?
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From: Good health is merely the slowest possible rate at which one can die
St. Jude Donor '04-'05-'06-'07
Originally Posted by flyersfan1088
I tried just bleeding and the pedal was somewhat softer for one pump, than it got hard again. Then I tried loosening the MC and the pedal got softer again. What should I look at next?
Team Owner
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
The only thing that would put force on the master cylinder with no pedaal pressure would be a booster pushrod that's unthreaded too far. These are adjustable, and can result in dragging brakes or a low vacuum assist if not adjusted right.
But if you swapped that two years ago, it wouldv'e been a problem right from the start.
I do believe the pushrod just sits in an indentation in the brake master piston. If it falls out of this indentation, it effectively would increase its length and cause the brakes to drag. I believe the only thing keeping this pushrod centered into the piston is the booster. If you pull the booster, you might find a problem there.
But if you swapped that two years ago, it wouldv'e been a problem right from the start.
I do believe the pushrod just sits in an indentation in the brake master piston. If it falls out of this indentation, it effectively would increase its length and cause the brakes to drag. I believe the only thing keeping this pushrod centered into the piston is the booster. If you pull the booster, you might find a problem there.
