OdesiTT

Sup guys!
I have a 06 Z Grand Touring with Brembo calipers.
I recently installed new Brembo brake pads and everything is perfect but when I'm driving backward and slightly press the brake pedal, its making awful whistling noice. It's so bad, that people around start to cry and I can see unbearable pain on their faces. I noticed some brown stuff on my rotors that I didn't had before. I could assume that pads and rotors need some time to whear but I have this brake pads about 90 days and put about 400 miles on it. Moreover, front rotors is OK, but there is StopTech pads(I'm happy with them, BTW).
I already reassembled everything and put extra grease on the back side of the pads and cleaned everything perfectly. Also, as you can see on the picture, outer radius of rotor have a normal metal color, but rest of it...
Roof is on fire!!! Please, help,!

travlee

iTrader: (8)

you might need to rebuild the calipers, have the rotors turned if not replaced

dcains

iTrader: (15)

If the calipers don't have sticking pistons or leaking seals, I can't imagine rebuilding is necessary.

Did you bed the new pads in properly? Did you change the brand of pads from what was previously used?

You're not going to find a shop to turn drilled/slotted rotors, but you can try burnishing the surfaces with a twisted wire brush wheel. Something like this:

http://www.brushresearch.com/brushes.php?c1=6

After that, try re-bedding the pads properly.

dkmura

iTrader: (64)

^^Agreed- most machine shops will not turn worn slotted/drilled rotors due to complications with their lathes. At issue here is light pedal pressure, which simply allows the pads to vibrate at high-frequency and causes that awful noise. Try backing up and using a firmer brake pedal application to stop the Z quicker. It'll still squeal a bit, but that's part of the deal of using a monoblock caliper.

i-break-things

What do the pads look like?
Are the leading and trailing edges of the pad beveled?

OdesiTT

Pads looks perfect. No mirrored surface or something. Looks like new.
It's beveled a little on top, because I have a 1mm lip on the rotor.

OdesiTT

Or you mean how its was looks like when was new? Its has the same shape like at the picture but Brembo(red back) Here it is, actually

i-break-things

How does it look now?
Does it still have a bevel?

If not that could be the cause of the noise.
Just pull the pads and take a grinder to them.

OdesiTT

Yes it does. It's almost like new.

i-break-things

i-break-things

This is a pic of one of my rotors. Totally quiet. about 20k of wear.

travlee

iTrader: (8)

what do the calipers themselves look like, all the seals good?

guitman32

iTrader: (15)

+1

Those rotors dont look bedded in to me. Could just be surface rust or brake dust making its way out after performing the brake job.

Perform 2 complete bed-in procedures and report back. If you used enough brake lube in the correct places the bed-in procedure usually cures squeals (assuming the pad compound isn't just noisy when cold - which if I think back to when I had the OEM Brembo pads they did do what you are describing).

i-break-things

Haha, I missed the 400 miles. As op stated did you bed the pads?

i-break-things

To bed pads.
2 moderate to aggressive stops from 60 mph down to 20 mph, then 2 moderate to aggressive stops from 40 mph down to 10 mph in rapid succession without letting the brakes cool and do not come to a complete stop. If you're forced to stop, either shift into neutral or give room in front so you can allow the vehicle to roll slightly while waiting for the light. The rotors will be very hot and holding down the brake pedal will allow the pad to create an imprint on the rotor. This is where the judder can originate from.

Then do 5 mod­erate stops from 35 mph to 5 mph in rapid succession without letting the brakes cool. You should expect to smell some resin as the brakes get hot.

After this is complete, drive around for as long as possible without excessively heating the brakes and without coming to a complete stop (Try for about 5 minutes at moderate speed). This is the cooling stage. It allows the heated resin in the brake pads to cool and cure.

After the brakes have cooled to standard operating temperature, you may use the brakes normally.

OdesiTT

I'm back with 1000 miles on it. Still have that noice, unfortunately.

OdesiTT

Contacted Brembo, they use to send me new pads. I'll let you know if its will fix the problem.

i-break-things

Sorry I haven't been on here in awhile.
I see you have pads coming...

Some other things to check. Wheels bearings. I started to get a little brake noise. As I pulled the wheels to check the brakes, which still look awesome. I noticed some place in the bearings. After changing out the rear bearing the brake noise is gone. The drives straighter/true and does not track/tram/follow the road grooves any longer. Today, a windy day, I would have to fight the wheel a little to drive down the hwy, nope. Straight as any arrow. Im doing the front wheel bearings today, little noise.

Last, check the parallel between the rotor and pads. Make sure a caliper is not out of parallel this miss alignment would cause noise also.

Good luck.

OdesiTT

How much its was cost you? I did front, and want to make rear, but it's much more complicated than front one.

i-break-things

$50 per side for bearings. The rear is easier than the front of the AWD.
For the rears unbolt the 1/2 shafts and drop them down.
The exhaust may be in the way of dropping them completely out.