Mc.Queen 964

Hi guys,

I have a horrible squealing pads when cornering, special in the front right caliper (SO IT SOUNDS WHEN I TURN TO THE LEFT).. and it has the mushroms. I looked them and I haven't got any oxide under the shims.. I've got new PAGID pads, but no racing ones, and the front rotors are turned...

Sometimes I have noise in rear ones, but I have to put the mushroms in the rear calipers, because I only have them in the front..

Guys.. What can I do?

Ducks964

I am no expert so when i had the issue with squealing brakes, i tried the mushrooms with no luck. Instead of really working to solve the issue, I switched to ceramic brakes and no squealing.

Rocket Rob

How tight are the pads in the calipers? They should move freely. I'm wondering if you may have some corrosion under the spring plate. You had a thread about this recently, did you find any corrosion?

https://rennlist.com/forums/964-foru...ng-brakes.html

campoj2

Did you try removing the mushrooms and installing self adhesive back pads?

911Jetta

In "light-duty" normal traffic, I experience a little bit of squealing just before my car comes to a stop. In can modulate the noise a bit by adjusting the pressure on the brake pedal. I was concerned that the noise might had appeared because I recently replaced my "mushroom" pads with self adhesive back pads...but after reading the link above (supplied by Rocket Rob), it confirms my suspicion that the noise is probably coming from the lip that has developed at the edge of the rotor. The brake pads don't contact this part of the rotor, therefore a slight lip develops as the rotor material is worn by brake pad contact.

So my thinking is, as I come to stop I subtly release pressure on the brake pedal causing the brake pad to release it's grip on the rotor...the loosen pad has room to move around a little bit so it catches the edge of the rotor lip that's been created. This movement causes the pad to sit at a slight angle and vibrate back and forth causing the noise. Again, I only experience squealing at the end of the braking segment, just before I stop.

I've got a "rookie" track day coming up...is a ~1 mm lip acceptable?

Off to do a "how to replace your front rotors" search...

Mc.Queen 964

I put new mushrooms and I haven't got any corrosion.. I looked at it.. And my front disc hasn't got any lip.. we turned them...

So I don't know what we can try..

Rocket Rob

If it were me, I would change your rotors. I seem to remember the wear limits for the rotors are 1mm per side. I don't have my spec book with me but I seem to remember that new rotors are 28mm thick, wear limit is 26mm thick.

By the way, good luck with your track day. They are a blast.

turbo911cm

Yep, 26mm is correct for front rotors.

Rocket Rob

How fresh are your wheel bearings?

911Jetta

Thanks for the info. guys. Stupid me, I didn't even think about the other side of the rotor.

Mc.Queen 964

Can't be bearings, because when it sounds, if i press the brake a little bit it disapear..

Regards.

Mc.Queen 964

I had 1mm per every side, and I turned them.. Now look like news..

911Jetta

I'm more worried about the 26mm rotor width spec. mentioned above by Rob and Turbo911cm.

-nick

I did mine a few hundred miles ago using Jurid pads and they squeal like a city bus after a mile of driving. They temporarily go quiet if I really put some heat in them.

- rebuilt calipers to remove all corrosion (new piston dust seals/etc)
- new coated Zimmerman rotors
- new pads/mushrooms/adhesive/wear sensors

I've done the bedding-in procedure twice (80-40mph hard braking about 3-4 times until I could smell the brakes).

When the weather allows I'm going to give the calipers a good pressure wash blast. Otherwise, I have a set of new PBR pads...

Rocket Rob

If your wheel bearings a worn, then the disk rotor will move, giving it a chance to vibrate (squeal) under light braking. Once the braking becomes strong enough, it will stabilize the disk and pads preventing noise. I wouldn't rule it out (yet).