Weird braking problem, noise. Help!
Posted: Sun Nov 20, 2016 6:54 pm
I recently did the rear disc swap and now have a noise that I can't seem to track down. First, let me give you some background. This is on my '93 GTZ (w/ABS). Front brakes are the 95+ J-body Wilwood 4 piston setup and have worked fine for almost a year now. No complaints.
I installed my Neon rear disc setup and although performance seems fine, after doing a few normal stops a noise will begin to develop that is driving me crazy. The sound happens when the pedal is depressed. It is more prominent at very low speeds, almost stopped. The noise is NOT a grinding sound and NOT a typical brake pad squeal. The best way sound I can compare it to is the sound of a school bus or dump truck braking. It sounds very much like some kind harmonic going through metal instead of a normal squeak or squealing pad. The sound is so loud that I can feel it through the chassis of the car. The only way to quiet it down (as I come to a stop) is to push harder on the pedal. The noise goes away quickly after I start moving again. Occasionally I can hear it slightly as I drive down the road, just after a previous stop. After stopping, I have noticed that the wheel on the caliper in question is noticeably warmer than the other 3, as if the caliper is sticking.
I've taken the brakes apart and checked everything. Everything looks normal, no signs of wear or anything obvious. I've greased the pins as well, although they show no signs of wear at all.
I've put everything back together MINUS the e-brake setup (just in case that was causing some issue).
I have bled the system repeatedly. Starting at the master/ABS module and working my way back. A couple things I've noticed:
(1) The master/ABS module has to bleed ports on it, which I've bled. I discovered these bleed nipples originally because I was unable to properly bleed the driver's side REAR caliper and the passenger side FRONT caliper (this is AFTER the rear disc install). Tracing the lines back, I found the bleed valves on the ABS module. After bleeding a ton of air out of one of the ports I was then able to bleed the above-mentioned calipers. It appears that the drivers front and passenger rear are tied together and the drivers rear and passenger front are also tied together, or at least correlated within the ABS/master cyl.
(2) After making that first connection, I became more acutely aware of the sound and where it appeared to come from. Interestingly enough, I noticed the sound (although quieter than when the car is rolling) when I bled the rear drivers side caliper. No idea how bleeding a caliper could make that noise, but it did, a few times. Other than that, I'm fairly certain that the front PASSENGER side caliper is also causing this same noise, although less frequently than the driver rear.
Any idea what could be happening? Could I have a bad ABS/master? What else could I be missing?
- Neon rear rotor/caliper/bracket
- Hawks rear pads
- NEW stainless hoses to rear calipers
- All brakes are recently bled and new fluid is at each caliper
I installed my Neon rear disc setup and although performance seems fine, after doing a few normal stops a noise will begin to develop that is driving me crazy. The sound happens when the pedal is depressed. It is more prominent at very low speeds, almost stopped. The noise is NOT a grinding sound and NOT a typical brake pad squeal. The best way sound I can compare it to is the sound of a school bus or dump truck braking. It sounds very much like some kind harmonic going through metal instead of a normal squeak or squealing pad. The sound is so loud that I can feel it through the chassis of the car. The only way to quiet it down (as I come to a stop) is to push harder on the pedal. The noise goes away quickly after I start moving again. Occasionally I can hear it slightly as I drive down the road, just after a previous stop. After stopping, I have noticed that the wheel on the caliper in question is noticeably warmer than the other 3, as if the caliper is sticking.
I've taken the brakes apart and checked everything. Everything looks normal, no signs of wear or anything obvious. I've greased the pins as well, although they show no signs of wear at all.
I've put everything back together MINUS the e-brake setup (just in case that was causing some issue).
I have bled the system repeatedly. Starting at the master/ABS module and working my way back. A couple things I've noticed:
(1) The master/ABS module has to bleed ports on it, which I've bled. I discovered these bleed nipples originally because I was unable to properly bleed the driver's side REAR caliper and the passenger side FRONT caliper (this is AFTER the rear disc install). Tracing the lines back, I found the bleed valves on the ABS module. After bleeding a ton of air out of one of the ports I was then able to bleed the above-mentioned calipers. It appears that the drivers front and passenger rear are tied together and the drivers rear and passenger front are also tied together, or at least correlated within the ABS/master cyl.
(2) After making that first connection, I became more acutely aware of the sound and where it appeared to come from. Interestingly enough, I noticed the sound (although quieter than when the car is rolling) when I bled the rear drivers side caliper. No idea how bleeding a caliper could make that noise, but it did, a few times. Other than that, I'm fairly certain that the front PASSENGER side caliper is also causing this same noise, although less frequently than the driver rear.
Any idea what could be happening? Could I have a bad ABS/master? What else could I be missing?
- Neon rear rotor/caliper/bracket
- Hawks rear pads
- NEW stainless hoses to rear calipers
- All brakes are recently bled and new fluid is at each caliper