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Kevin Lewis's Avatar
 
Join Date: Apr 2002
Location: AZ
Posts: 91
Front Brakes making loud high pitched humming noise?

I just replace the rear brakes, rebuilt everything, bleed the brakes and worked fine. So, I thought lets do the front, there are suppose to be easier. Rebuilt the calipers, new o-rings for pistons, boots, o-rings for split calipers, bleed the brakes- 2 hour chore. Drove the car and the right front brake make a high pitched humming noise. If I tap the the brake pedal it goes away for a moment, but comes back. Gets worse when the brakes get hotter. Put it back on the lift checked the venting clearance on both front brakes, couldn't even get a .002 gap between the rotor and pad. Whats the deal? How do I adjust the front venting clearance .002-.008 if there is no mechanical adjustment? Please help me my ears are still ringing.
Old 11-20-2004, 06:22 AM
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i don't think there is any clearance on the front. Is it possible one of the calipers on the noisy side isn't retracting all the way? I would suspet a blocked pasage in the caliper or in the line. Disconnect the brake line and flush that first. I think the odds are pretty good it is a piece of something in the line.
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Old 11-20-2004, 08:43 PM
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Did you re-surface/replace the rotors?

Sounds like a warped rotor to me...

The front brakes are also self adjusting...
Old 11-20-2004, 09:02 PM
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I had this exact same problem after installing ferodo pads . On my car it was intermittent and more pronounced in the corners. I suspect it is caused by sticktion in the brake puck or uneveness on the back side of the pad.
I solved it by removing the pads and applying some CRC anti squealing compond to back of each pad. This stuff is a bright orange non hardening substance which keeps the pad in contact with the brake puck. I re-bled the brakes and the problem was resolved. I went back and did the rear brakes with the anti-squeal compound which eliminated an intermittent squealing under hard braking.
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Last edited by schosh; 11-22-2004 at 04:02 AM..
Old 11-21-2004, 05:13 AM
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I found the problem. After inspecting the caliper assy I noticed I had the inside squeel plate upside down. It should reside on the top pin and I had inadvertly put it on the bottom pin, because I turned the piston 180 degrees the worng way. When the brakes were applied the squeel plate would push up against the brake pad and would not let it retract. So, after pulling the caliper off and getting the piston turned to the right position and replacing the bent up squeel plate, I was noise free and the problem was solved. Thank you all for your replies.
Kevin
Old 11-22-2004, 05:38 AM
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