Help -- replaced pads and now have strange noise / vibration

[HP Man]

Hi,

I have an AP Racing BBK on my car and recently destroyed a set of Mintex Extreme pads at a local track day (see here for details http://www.m3post.com/forums/showthread.php?t=437834).

As I daily drive my car, I ordered a new set of Mintex Extreme pads for the front and installed them this weekend. I followed the instructions regarding installation and bedding, however, I now have an odd sound coming from my front end. It is a moderate rubbing / grinding sound (almost similar to the differential clutches slipping around slow sharp corners) that only appears while turning at slow speed and without the brakes applied. It is most pronounced with slow, moderate turns, rather that very sharp turns. It also results in a bit of vibration through the steering wheel. The sound / vibration does not occur in a straight line, nor does it occur at speed or while braking.

I jacked the car up and can confirm that the tires are not rubbing and the wheels turn without excessive pad drag (I initially thought that it might be a stuck piston that is causing brake drag, but this does not appear to be the case).

Any thoughts on what may be causing this?

Thanks in advance.

[david @ eas]

As I mentioned over email, we've been getting in contact with AP Racing Engineers on what possible issues you might have. Though at times it could seem like a simple problem, we want to ensure that if there is something wrong, that we take care of it.

As I also mentioned over email, the Engineers over at AP, though incredibly intelligent, can take a bit of time to respond to us. I'll update you over email to let you know what happens.

[HP Man]

Originally Posted by jurrian @ eas

As I mentioned over email, we've been getting in contact with AP Racing Engineers on what possible issues you might have. Though at times it could seem like a simple problem, we want to ensure that if there is something wrong, that we take care of it.

As I also mentioned over email, the Engineers over at AP, though incredibly intelligent, can take a bit of time to respond to us. I'll update you over email to let you know what happens.

Thanks Jurrian. I think this is a different issue than we've been corresponding about via email. I never had any funny sounds or vibration with the old pads, even for the 2 weeks that I drove the car after I melted them at the track. The sounds / vibration described above only arose after I installed the new pads.

Any insight to this current issue would be appreciated.

[rzm3]

Do you still have your cooked pads? I assume there is at least a little bit of pad left? Try putting them back on one side at a time, then you can figure out where the sound is coming from. Should be pretty easy to do thanks to the removable bridge.

[STALKER]

Your pads might not be releasing properly.

[HP Man]

Thanks for the replies. I've isolated the sound to the driver's side front brakes. They make the odd sound I described above when manually turned. I removed the caliper and pads, cleaned everything, re-assembled and they still make the same sound. I did note that the leading and trailing edge of both the inside and outside pad were more worn than the middle. Could this be the problem?

[HP Man]

So I seem to have fixed the noise / vibration issue. I removed the new pads on the driver's side front caliper and slightly chamfered the leading and trailing edges of both the inside and outside pad. After reassembly, the grinding noise and vibration are gone. I'm not sure why the noise and vibration was present in the first place, but I'll be content not to know as long as they don't return.

[BimmerRob08]

Originally Posted by HP Man

So I seem to have fixed the noise / vibration issue. I removed the new pads on the driver's side front caliper and slightly chamfered the leading and trailing edges of both the inside and outside pad. After reassembly, the grinding noise and vibration are gone. I'm not sure why the noise and vibration was present in the first place, but I'll be content not to know as long as they don't return.

Excuse my ignorance, but you chamfered the edges? Shaved them to a 45 degree angle? Or trimmed them? I'm trying to get a visual image of what you did to them.

I wonder why that would fix the problem, if it did and when you got the first set of pads, if they were not chamfered, then why didn't they cause this issue? I'm curious, got some AP's in the mail.

I wonder also if while you were removing and then replace the pads, if something was stuck or lodged and you un-stuck them with out knowin. If that's even a possible senario. Glad at least you took care of the issue.

Cheers,

[JCtx]

Chamfering should only eliminate noise, not a vibration. Pads were not seated right or something, but apparently you reinstalled them correctly the second time .

[HP Man]

Hmmm, the noise is back, so I'm not sure what the issue is. Interestingly enough, I put the old cooked pads back in and drove for a while and all the issues were resolved. Obviously, there is some issue with the shape of the new pad versus the shape of the rotor (the rotor is scored from me overheating it at the track). I'm going to drive for a while and see if the noise goes away as the pad wears.

[BimmerRob08]

Well hope I'm not a bit paranoid but I'm starting to worry a little since I got some AP's in the mail to me. I won't be putting as much stress on them as you did for the only reason is to prolong the pad/disc service life as I'm not read to burn through them in a few days.

But since you replaced pads and have very low miles relatively for what you were doing on the track. I would have thought they would hold up better in this aspect. Is it because you didn't go with race pads for the type of driving?

[HP Man]

Originally Posted by BimmerRob08

Well hope I'm not a bit paranoid but I'm starting to worry a little since I got some AP's in the mail to me. I won't be putting as much stress on them as you did for the only reason is to prolong the pad/disc service life as I'm not read to burn through them in a few days.

But since you replaced pads and have very low miles relatively for what you were doing on the track. I would have thought they would hold up better in this aspect. Is it because you didn't go with race pads for the type of driving?

Yes, you are bing paranoid.

Others have gotten very good life out of the Mintex Extreme pads (check out some of the posts JAJ has made about his AP Racing kit). I did not simply because I overheated them and they melted. I have learned my lesson and now know that for my driving ability and style, I need a different pad compound (I also need to manage my brakes a bit better).

The AP Racing bbk is an excellent product. If you brake aggressively on the track, just be sure you are using an appropriate pad compound.

[BimmerRob08]

Originally Posted by HP Man

Yes, you are bing paranoid.

Others have gotten very good life out of the Mintex Extreme pads (check out some of the posts JAJ has made about his AP Racing kit). I did not simply because I overheated them and they melted. I have learned my lesson and now know that for my driving ability and style, I need a different pad compound (I also need to manage my brakes a bit better).

The AP Racing bbk is an excellent product. If you brake aggressively on the track, just be sure you are using an appropriate pad compound.

I trust ya, Lot's of $$$$ for a BBK, just wanted to make sure it's not a defect but just user issues. Maybe new discs might fix your issue too? Now we're talking more bucks of course.

I'm still waiting for mine to come in the mail. Damn APO system takes for ever! Pics to come when installed.

[mastek]

Is it a "humming" vibration sound