psam550

Hi Follow Members,

The front, left brake on my 2006 550i is lightly squealing at low speeds/light pressure. My search of this forum leads me to believe that the brake pad sensor is the culprit. (Still plenty of pad.) One Member stated in an old thread that slightly sanding the sensor down, rounding off its edges and applying brake grease to the sensor will alleviate the noise. True? If so, can someone here explain in better detail:

1. How much to sand it down?

2. How to round off the edges?

3. Where to apply the grease on the sensor?

BTW, I have already had the front brakes removed, cleaned and greased to alleviate noise, which helped some but did not kill the problem. Thx for your help!

Psam550

tonyb635

If you still have plenty of pad and the sensor was installed correctly, it's not the sensor. The sensor will only make contact when the pad is worn and needing to be changed. It's possible there could be a piece of unwanted material in there causing this noise. You could remove pads and hit them with some 120 grit then 180 grit. Not much, just enough to clean them off a little. Place the sand paper on something flat and slide the pad back and forth a few times.

turboawd

i think i get the same sensor rub noise.

tonyb635

If the sensor touches the rotor, it will trigger your brake light message to change your pads.

I have a similar problem and I am sure it's caused by the cheap ass rotors I had to install. A weekend job with little planning and then I damaged the rotor while removing it. Went to AZ and they got me a set the following morning. The rotors have been on now for maybe 10 months and the look like they've been there for ten years! A really cheap rotor. They squeal for the first four or five applications, then they are ok. The hubs are rusty and so they will be going in the trash soon!

psam550

Well, I did it. I pulled the sensor, filed the top and filed down the edges to accentuate the chamfer/triangle edges of the sensor, like I read in another post on another site. It worked!! Noise gone. I feel like a real "shade tree mechanic". Saved a few bucks, too.

Now for the bad part: my brake booster/servo failed the next day. Now the brakes are quite and they don't work! That's too quite! Stealer took me for $1k. What a screw job. The part can be had for between $250 to $450. Labor $200. So, I paid $1k for a job should cost about $600. (And my wife's Oddessy just had a light go off. At least the Honda shop is much cheaper.)

That's life. I still love my car.

roskinc

im actually using AZ rotors and pads and believe it or not, i have zero noise issues, and very low brake dust and very surprised at the grip i get on the braking...maybe its just me but i like the feel of these better than the OEM pads/rotors i had on previously. the duralast gold brakes are made by BOSCH and just packaged as autozone duralast brand. company guarantees noise free to commercial accounts and with labor reimbursed if noise does happen. its all in the cleaning, and using the right stuff when you do the job.

the bad thing is AZ rotors get all rusty at the hub and the end lip of the rotor, all their rotors have this issue, but i had painted mine with rustoleum brush on paint (as well as the calipers) and they look perfect still. being able to change these brakes in less than 30 minutes, and having lifetime warranty pads, and 2yr rotors...why not! can change them anytime, although i haven't had to, VERY pleased with these. i never thought id be using autozone pads and rotors on my car, but i do love these.

tonyb635

Are you referring to the metal sensor or the small electronic one? Either case did you measure how much pad is actually remaining? It possible that the metal sensor could have be bent or damaged and causing it to touch. But really either way you should verify the pad thickness to confirm this. The electronic sensor should hit first. But as previously said they are there to notify and warn you to inspect and or change the pads. If the electronic sensor is touching then you most likely need to change the pads. The sensor will cost around 17.00.

psam550

Thx, Tonyb635. The sensor was touching the pad, but I have plenty of pad left, a fact the dealer confirmed the next day. The sensor is very long. And it did not trigger any pad warning light. The sensor is made with a green ceramic like material with electronic copper looking things embedded. I would be happy to post a link to the other site where a claimed master mechanic posted the sanding/filing idea to eliminate the noise. There is a BMW service bulletin, too, saying the geometry of the sensor may cause noise. I think filing the edges at an angle is what did the trick. And I also cleaned the unit and put a little brake grease on the side and back of it. Noise gone. Thx. Psam550.

psam550

Here is a link. See the post by "ex-tech"

2007 530i w/sqealing Brakes - Bimmerfest - BMW Forums

Here is another link. See the expert's answer at the bottom. It worked for me.

http://www.justanswer.com/bmw/1fqgu-...acelifted.html

Psam550

tonyb635

Wow, very interesting... When I've changed my brakes there is clearly a recessed area for the sensor and you can see as the pad wears the sensor will eventually contact the rotor providing the ground. I can't see any possible way my sensor could contact the rotor without wear. Ok, there is still a good amount of pad left but I guess it's kinda your pre-warning event. Then there is the hard metal device on each inner pad that eventually if left will contact and is supposed to scream at you. The electronic sensors are on my LF and RR. If I recall correctly, the wear required to contact the sensor was like ~ 2/3. At that point, I think I would just go ahead and change them, but if I had 50% or more yeah maybe file them, but this still doesn't make any sense to me. I'll be changing my front brake again soon since I had to install some crap rotors and will have a deeper look at this