[Liquidpaper]

Maybe you guys can help out:

I have EBC Yellow pads, stainless lines, fluid, stock everything else (with brakes).

With both these pads (and the Porterfield R4S pads), I get some slight squeaking. The weird part is, I get the squeaking (light) when I am not on the brakes, but just driving along. As soon as I apply some pressure, the squeaking stops. Brakes work fine otherwise.

Does anyone have any idea what might be causing this? This tends to happen when the brakes are cold. As they warm (a few hard stops, etc.) it tends to go away. I've looked around the interwebz for an answer, and other people have this problem with disc brakes, but it is definitely not common.

Any help is appreciated.

[Mywifes335]

New rotors or old rotors?

[Liquidpaper]

Original rotors.

[csg]

it's possible you have some pad deposits on the rotors and the pads are just brushing the deposits during normal driving. This same thing happened to me when I street-drove my Hawk DTC60s between weekends on basically new-stock blanks. Street driving the pads all-but destroyed the rotors for the following weekend, horrible deposits. I had to quit early in the last session because the car was unsteady under braking.

[Liquidpaper]

Originally Posted by csg

it's possible you have some pad deposits on the rotors and the pads are just brushing the deposits during normal driving. This same thing happened to me when I street-drove my Hawk DTC60s between weekends on basically new-stock blanks. Street driving the pads all-but destroyed the rotors for the following weekend, horrible deposits. I had to quit early in the last session because the car was unsteady under braking.

This very well could be the case. Luckily, Yellowstuffs are not as abrasive on the rotors as Hawk DTC60s. Again, as the brakes heat up, the noise goes away. I guess that is what I get for having slightly more aggressive than stock brake pads.

[Mywifes335]

Originally Posted by Liquidpaper

Original rotors.

Your old rotors might not be fully mated to the new pads. The old rotors aren't smooth, despite how it looks to the naked eye. So these grooves left by your old pads are likely brushing up or scratching along unevenly with the new pads, causing resonance - squeaking.

You can try bedding them in again but it might make it worse. Suggest getting new rotor blanks or getting them cut on a lathe.

Perhaps try rubbing a bit of ceramic (permatex) grease on the backs of the pads and reinstalling.

[Liquidpaper]

Originally Posted by Mywifes335

Your old rotors might not be fully mated to the new pads. The old rotors aren't smooth, despite how it looks to the naked eye. So these grooves left by your old pads are likely brushing up or scratching along unevenly with the new pads, causing resonance - squeaking.

You can try bedding them in again but it might make it worse. Suggest getting new rotor blanks or getting them cut on a lathe.

Perhaps try rubbing a bit of ceramic (permatex) grease on the backs of the pads and reinstalling.

I thought this might be the case. These rotors are on their last legs -- my plan was when these pads die out, its rotors/pads time. I'll ask my mechanic next time I'm in the shop. Thanks.

[Mywifes335]

No problem. I used to swap pads in/out before/after track days so really accustomed to this.

[Liquidpaper]

Originally Posted by Mywifes335

No problem. I used to swap pads in/out before/after track days so really accustomed to this.

The funny thing is that I don't swap my pads. However, my rotors are pretty heavily grooved at this point (I'm at about 22k miles and have a lot of track time on them), so I think its just the end of line for them.

[Mywifes335]

22k miles is a lot!

[Liquidpaper]

Originally Posted by Mywifes335

22k miles is a lot!

Yeah. I've heard of people getting as much as 28k on the original rotors, even with track abuse, but maybe my time is up. Thanks for the input.

[Pparana]

22k!

partsgeek has various rotor options starting at $50. No need to run them anywhere near that long. One set of race pads and I put on new ones. I get noise when i go back to ebc yellows (use them as street pads, compatible with my race pads). I suspect if you put new rotors on you would be shocked how much better the car stops.

[Mywifes335]

Yeah since it's not a "real" M, rotors are cheap!

I have the M235i...just in case.

[Liquidpaper]

Thanks guys.

How hard is it to bed used pads on new rotors? I think my pads are fine, just the rotors need changing.

[Mywifes335]

Easy. I don't remember the official sequence but drive around a bit do some medium stopping then do 3-4 successive 70-0mph stops. Usually works for me.

Just be careful.

[Tpeterson]

Originally Posted by Liquidpaper

Thanks guys.

How hard is it to bed used pads on new rotors? I think my pads are fine, just the rotors need changing.

Here's a link on how to bed in brakes from previous thread about disappointing brakes on the 2series

http://www.zeckhausen.com/bedding_in_brakes.htm

[Mywifes335]

Near stop prevents accidentally holding the pad onto a hot rotor which would cause warping.

Don't keep brake on at stop after bedding in.

On track days I either keep the car in gear or use wheel chocks - no parking brake after runs.

[Liquidpaper]

I always bedded my brakes in a similar way - some normal driving + 6 - 10 hard stops from 60 to 10, but don't let the brakes clamp and warp the rotors.

[casper83]

Originally Posted by Liquidpaper

Maybe you guys can help out:

I have EBC Yellow pads, stainless lines, fluid, stock everything else (with brakes).

With both these pads (and the Porterfield R4S pads), I get some slight squeaking. The weird part is, I get the squeaking (light) when I am not on the brakes, but just driving along. As soon as I apply some pressure, the squeaking stops. Brakes work fine otherwise.

Does anyone have any idea what might be causing this? This tends to happen when the brakes are cold. As they warm (a few hard stops, etc.) it tends to go away. I've looked around the interwebz for an answer, and other people have this problem with disc brakes, but it is definitely not common.

Any help is appreciated.

I had an issue several years ago with squeaky breaks and research led to harmonics. The brake pads would vibrate at a high frequency and cause a squealing noise. If this is the case for you the squeal potentially goes away when hot because the frequency of oscillation changes.

tips from Wagner on how to dampen vibration:
http://www.wagnerbrake.com/tech-tips...oise-solutions

[Liquidpaper]

Originally Posted by casper83

I had an issue several years ago with squeaky breaks and research led to harmonics. The brake pads would vibrate at a high frequency and cause a squealing noise. If this is the case for you the squeal potentially goes away when hot because the frequency of oscillation changes.

tips from Wagner on how to dampen vibration:
http://www.wagnerbrake.com/tech-tips...oise-solutions

This is very informative. Thank you.

[Liquidpaper]

So I picked up some new rotors and got them installed (needed a brake fluid recharge/swap anyway). Fixed my problem (mostly). Still makes a bit of noise, but I think that is in part due to the Yellowstuff compound (it's pretty aggressive) and the fact that the pads are not totally bedded yet.

I took it out last night on the PCH (only road in town that doesn't have traffic that you can get up to 60 mph on) and did the bed in procedure. I got a nice transfer layer going, but the Zeckhausen guide says that it make take two bed-in sessions to get the brakes up to maximum grip, although they are much better today than they were when I picked up the car from the shop yesterday.

Related note -- Stoptech makes some reasonably priced (cheaper than OEM) slotted/vented (not cross-drilled) rotors for the M235i. My mechanic was actually pretty impressed. Also, I swapped my brake fluid to this Torque RT700 fluid. It's not cheap ($33 a half liter), but holy crap does it work well. I did 15 or so stops from 60-70 last night to bed my brakes, and the pedal never even began to get soft. I would recommend if you wanted to try something different from the standard Gastrol SRF fluid (or a Motul fluid). It's also made in America ('Merica), up in Sonoma, CA.

[Mywifes335]

Glad you got it sorted man! ��

Where did you buy the rotor blanks from?