braking problem

[shavivs]

Hello
I wonderd if anyone here have this...
When I drive hard on the car after a few brakes they start
to make a bad noise , like I have a problem with the rear bearings .
If i let them to rest for a two minutes its gone but if i go fast
again its very disturbing and sounds very bad .
The car has 3'500 KM.
Thanks

[tkbr0wn]

My first guess is that you are not used to M-Compound brakes. They do make a different sound on hard braking and it is normal.

[MDORPHN]

ABS

Neil

[Dackelone]

I don't have a M... but that does not sound normal to me. Did you ask your dealer what they think?

Do your brake rotors have any serious (deep) groves? Or maybe blue in color due to glazed braking(lots of stop and go driving) the rotor surface can get glazed over. ???

[shavivs]

The brakes are brand new and the originals.
Abs??? are you kidding? i know very well how the system works
and the sound starts sooner then the system even think to interfere
as i sad the car have only 3500 km

[dlong82]

If you are talking about a "furling vibration" noise that occur under heavy braking (non ABS braking), it probably comes from the cross drilled rotors. That has been my experience with my 1M and other cars I have with cross drilled rotors and cars I have switched to cross drilled rotors.

Watch some of the track day videos on the site; you can hear it. If that is what you are hearing, it is not and indication of a problem.

Good luck.

[clived]

It is of course entirely possible to hose a set of pads and damage the discs well inside 3500km if you're driving hard enough...

[EmmDrei]

@Shavivs: I would assume you are experiencing cementite build up on your rotors. There are two ways I have found, that you can create cementite when applying the M39x brakes (true for the M3 as well as for the 1M). Option 1 is to run the brakes hot (i.e. during track use) while the stock pads are installed. This does not seem to be true in your case. Option 2 is to constantly apply the brakes for longer periods of time but with very little pressure. I would assume nobody explained to you how the brakes should be broken in?

[gnpower]

Originally Posted by shavivs

Hello
I wonderd if anyone here have this...
When I drive hard on the car after a few brakes they start
to make a bad noise , like I have a problem with the rear bearings .
If i let them to rest for a two minutes its gone but if i go fast
again its very disturbing and sounds very bad .
The car has 3'500 KM.
Thanks

Back to the dealer.

[shavivs]

I have the car for a two month. i drive very gentel until 3000 km .
when i started to push the car the bad sound started immediately.
Unfortunately we have only 4 m in Israel and they dont know nothing
about the car in bmw garage.
It is amazing but they didnt know that the car need to do service in 2000 km
they didnt know what kind of diffrencial oil they need , and until now i wait
for the gear oil .
sad , very sad .
All the information i get from here.
dlong 82 - i think you understand what im talking about.
do you think that is normal?
EmmDrei- thank for the information - i think the 1m is my first
sport car that comes with drill brakes. are all the drill brakes
make this kind of disturbing noise?

[EmmDrei]

Originally Posted by shavivs

i drive very gentel until 3000 km .

And imho that is exactly where your problem is. The M3 brakes like "short and hard" braking. They don't like "long and gentle". If the build up is not too bad, then it can be rubbed off the rotors by applying the brakes hard a couple of times as if you are breaking new pads / rotors in. If you are unsure what I am talking about, take it to the shop and have them exchange the discs.

[h-manuk]

Originally Posted by shavivs

Hello
I wonderd if anyone here have this...
When I drive hard on the car after a few brakes they start
to make a bad noise , like I have a problem with the rear bearings .
If i let them to rest for a two minutes its gone but if i go fast
again its very disturbing and sounds very bad .
The car has 3'500 KM.
Thanks

Hi,
Im pretty sure what your experiencing is completely normal. This is quite a normal M braking behaviour and it does mention this in the 1M booklet that comes with the car. No harm in getting it checked out though!

[Dackelone]

Originally Posted by EmmDrei

And imho that is exactly where your problem is. The M3 brakes like "short and hard" braking. They don't like "long and gentle". If the build up is not too bad, then it can be rubbed off the rotors by applying the brakes hard a couple of times as if you are breaking new pads / rotors in. If you are unsure what I am talking about, take it to the shop and have them exchange the discs.

^^+1. Brake rotors have glazed build up from driving slow in stop and go traffic. You either need to drive hard and burn the built up pad material off the rotor... or replace the rotors.


read the first two paragraphs...

http://www.tirerack.com/FAQ/results.jsp?category=Brakes

[shavivs]

Dackelone- thanks for the artical . i dont think that my brakes are overheated ever
beacuse i didnt work so hard on them .
tommorow i will try to look if there is a scratcheson the on discs brakes .
thank you guys for the helpfull information .

[Dackelone]

One other thing you could try is to spray on some Brake Kleen(made by CRC or the like) onto the brake rotors. This will remove any gease or glazing on the rotors. Then go out and use the brake briskly, medium to hard. Be sure to allow the brakes to cool off before you park the car. Also be carefull with the BrakeKleen running/dripping down onto your alloys. It can stain them. It would be best to remove the wheels and spray the rotors down.



PS: In Germany we don't have problems like that... bc we have something called an Autobahn where we are either at WOT or braking pretty darn hard because some sub one liter car decides to pass a truck right as we are about to over take them! So we end up using the brakes fairly hard over here.

[Artemis]

@shavivs: have a look at this:
Source: http://www.raceshopper.com/tech.shtml

"Brake Pad Bedding-in:
For optimal use of any given brake system, the pads and rotor have to be compatible with each other. The bed-in procedure establishes that compatibility between the pad and rotor. This is achieved by a combination of rubbing speed, temperature, line pressure, and inertia. Bed-in is also influenced by pad and rotor material chemistries. It is always recommended that only compatible pads and rotors be used in any given application.
Bedding in advantages:
1. Gradually heat treats the rotor and eliminates any thermal shock in the rotor.
2. Burn off volatiles and moisture from the resin that is near pad surface.
This will eliminate “green fade.”
3. Establish a layer of transfer film about a few microns thick on the rotor surface. Shearing of the film during friction is an effective source of friction force. Otherwise, when using a freshly ground rotor without the transfer film, the main friction force would come from cutting, plowing, or scoring the asperities on the rotor surface. This leads to inconsistent braking effectiveness.
4. Mate the two surfaces to a near perfect geometrical match, so that the contact area is high, and therefore the friction force is increased.
5. The performance of a fresh rotor/fresh pad system would be inconsistent. This is due to ever-changing structures and properties of the two mating materials. Bed-in of pads and rotor will form a stable transfer film.
6. If bedding in procedure is not applied, a stable transfer film may not be established for a long time. In other words, the rotor surface would have to be constantly regenerating a film that is not quite stable for a long time. This effect would reduce the performance and increase the wear."

"What causes brake pad glazing?
Brake pad glazing is caused when the brake pad friction material is overheated.
This results in crystallized friction material on the pad surface and the brake disc.
Typical symptoms of glazed brake pads include: Poor stopping performance, vibration or brake judder, and cracks or fissures in the brake pad material.
Pad glazing is typically caused by operating the brake pads at a temperature above the specified temperature range of the friction material or not properly following the 'Bedding-in' instructions for the brake pads. Always follow the manufacturers brake pad bedding-in instructions and use a brake pad that has a temperature range that is sufficient for its intended use."

"What causes brake pad failure?
There is no single answer to this question - there are simply too many variables.
However, in general, pad failure is caused by excessive heat. Brake pad compounds are designed to operate within a certain temperature range. When the pad is overheated to a temperature above what the material was designed to handle, it will wear at an excessive rate, crumble, decompose, and the like."

[Dackelone]

I found this old SIB on squeaky brakes from BMW Canada. It might help you out.
BRAKE SQUEAL.pdf



I also found this interesting thread on the e90 forum. Its mostly for early three series, but it might help with your dealer.

LOOK at Post #13 and the video on page two!

SI B 34 08 08
Brakes October 2008
Technical Service

http://www.e90post.com/forums/showthread.php?t=235395



Dack

[shavivs]

Hi Dack
The squeaky brakes is not the problem in may car .
As i said the sound is like a broken bearings if you know what i mean .
Today i went to bmw main garage . they looked at me like i felt out of the sky
in Israel this cars are so expensive so we have here 3-4 m3 e92
and 4 1m . they have no expirianse on them .
they ask me to come next week and they will call to the maneger service.
I cant belive that bmw made the car like this .
I let you know what happend
shlomi

[Dackelone]

Ok Shavivs - I understand now. It sounds like a bad wheel bearing... RrrrrrrrRRrrrrrRRrrr.

I had that problem on my wornout front rotors. After I changed the rotors and pads the noise went away. I only heard that bad wheel bearing noise when really braking hard... 80% braking or harder.

It sounds like you need new brake rotors and pads and a wear sensor. Can you ask your dealer to just replace these parts under the warranty?

[shavivs]

I can ask them to ...
You right - you can hear the bad noise only on hard braking .
Now the big question - is this sound come from the brakes or from the lock differncial?

[Dackelone]

Originally Posted by shavivs

I can ask them to ...
You right - you can hear the bad noise only on hard braking .
Now the big question - is this sound come from the brakes or from the lock diff?

It is coming from the brakes - trust me. Mine went away after I replaced my pads and rotors (and the wear sensor). Just make sure the tech uses a good wire brush and romoves all the rust that builds up on the front wheel bearing hubs - where the rotor mates up too.

Brakes are cheaper to replace than a LSD diff.

[shavivs]

that is true . i belive that the price of lock diff here is the same price like you pay
for your 1m in germany .
they crazy here ...
thanks - i will tell them to start with the rear brakes .