**Brake question, please reply**
07-03-2002, 07:09 PM
#1
Thread Starter
**Brake question, please reply**
OK, it's not for my S2000, but I have a question and if you can answer it I'd be very thankful. I'm working on my '87 Mitsubishi Starion redoing the brakes. There was a lot of shaking when I would stop and the brakes just didn't feel strong. I purchased some decent Raybestos pads and had the rotors turned. I put everything back together and took a short drive. when I came to my first stop I noticed that the car wanted to stop on it's own, so when I got out I checked the rotors and sure enough...the right rear (passenger side) was turning colors...it was stuck on.
Here's my question. How do I know if my caliper is seized? When I took the rotor off and pushed on the brake, the piston comes out but doesn't go back in, and nothing slides at all, it's just the piston moving. This may sound funny, but when I try to tighten the caliper it tries to pull the rotor that way, kinda' pull it out of line.
Is there any way I can tell definitively that I need a new caliper?
Thanks for any assistance.
Andrew
Here's my question. How do I know if my caliper is seized? When I took the rotor off and pushed on the brake, the piston comes out but doesn't go back in, and nothing slides at all, it's just the piston moving. This may sound funny, but when I try to tighten the caliper it tries to pull the rotor that way, kinda' pull it out of line.
Is there any way I can tell definitively that I need a new caliper?
Thanks for any assistance.
Andrew
07-03-2002, 08:13 PM
#2
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In general there is one of two possible things wrong.
1) The brake hose, from the caliper to the chassis, is bad.
2) The caliper piston is stuck/sticking.
To determine which is the problem lift the wheel off the ground and remove the wheel. Place the transmission in neutral. Depress and release the brake pedal. Try and turn the rotor. If the rotor turns freely the problem may be intermittent. If the rotor is stuck unscrew the bleeder valve ~ 1/2 turn.
1) Does fluid come out of the bleeder valve under high pressure and does the rotor now turn freely? If so, the brake hose is bad. What normally happens inside the hose is that a small piece of the inner lining of the hose partially separates and forms a "flapper valve" inside the hose. The fluid pressure can't return to the master cylinder when the pedal is released. The high pressure fluid is trapped between the "flapper valve" and the caliper piston.
2) Is the rotor still stuck? If so, the piston is stuck in the caliper bore. The only thing that "returns" the piston when the brake pedal is released is the caliper seal. It is shaped in such a way that the seal distorts when pressure is applied behind the seal and then the seal returns to its undistorted shape when the pressure is released. The amount of travel due to the seal distortion is very minimal (~ 0.005") and not easily seen.
The initial problem you were experiencing with the shuttering during brake application is called "brake jutter". It was likely caused by the bad hose/sticking caliper piston. They overheated the rotor and caused it to warp.
I hope this helps, good luck.
1) The brake hose, from the caliper to the chassis, is bad.
2) The caliper piston is stuck/sticking.
To determine which is the problem lift the wheel off the ground and remove the wheel. Place the transmission in neutral. Depress and release the brake pedal. Try and turn the rotor. If the rotor turns freely the problem may be intermittent. If the rotor is stuck unscrew the bleeder valve ~ 1/2 turn.
1) Does fluid come out of the bleeder valve under high pressure and does the rotor now turn freely? If so, the brake hose is bad. What normally happens inside the hose is that a small piece of the inner lining of the hose partially separates and forms a "flapper valve" inside the hose. The fluid pressure can't return to the master cylinder when the pedal is released. The high pressure fluid is trapped between the "flapper valve" and the caliper piston.
2) Is the rotor still stuck? If so, the piston is stuck in the caliper bore. The only thing that "returns" the piston when the brake pedal is released is the caliper seal. It is shaped in such a way that the seal distorts when pressure is applied behind the seal and then the seal returns to its undistorted shape when the pressure is released. The amount of travel due to the seal distortion is very minimal (~ 0.005") and not easily seen.
The initial problem you were experiencing with the shuttering during brake application is called "brake jutter". It was likely caused by the bad hose/sticking caliper piston. They overheated the rotor and caused it to warp.
I hope this helps, good luck.
07-04-2002, 07:14 AM
#3
The rear calipers on some cars are designed very differently from the fronts. I have seen some rear calipers where the piston has to be screwed into the caliper housing. I am pretty sure that this is due to the parking break mechanism.
If the piston has a flat surfuce with a couple crossing slots, then you need to use a large screwdriver to turn it clockwise about a half turn or so.
When you assembled the rear brakes, did the one in question have allot of drag, or did you have a hard time getting together? If so, I'm certain this is why.
If the piston has a flat surfuce with a couple crossing slots, then you need to use a large screwdriver to turn it clockwise about a half turn or so.
When you assembled the rear brakes, did the one in question have allot of drag, or did you have a hard time getting together? If so, I'm certain this is why.
07-04-2002, 08:43 AM
#4
Thread Starter
Wow, thanks greenlight, I'm printing this as I write.
Gernby, yeah, the one with the problem had a lot of drag, and the brake pad was really bad on one half of the SAME side, as if it were in there crooked, not worn evenly at all.
This board ROCKS!
Thanks again guys.
Andrew
Gernby, yeah, the one with the problem had a lot of drag, and the brake pad was really bad on one half of the SAME side, as if it were in there crooked, not worn evenly at all.
This board ROCKS!
Thanks again guys.
Andrew
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