Had the dealership look at my brakes
 

I have a brake squeal that is becoming a growing problem. It started at as a slight squeak here and there, then you could hear more metal and metal contact. I had to dealership take a look at it, and they said that there was a lot of brake dust in the wheels, and so they put the brakes through a "burn" process where they made a few aggressive stops from 40 mph to 0 mph. They said that this would clean out the brake dust. However, lately my car has been squealing a lot more often. The squeal is louder, and occurs not only when I come to a complete stop, but also when I hit the brakes at other speeds, i.e. 40 mph, 60 mph. I also hear a louder metal to metal contact; It is a rough sound. I am not sure what I should do about this? The dealership said that there is 50% life on the brake pads. Is there somthing wrong with the rotors? Any suggestions and advice is greatly appreciated. Thanks in advance.:)

Before the "burn in" process will work the rotors should be scuffed with sandpaper on emory cloth. This needs to be done to break the glaze on the rotors for used brakes. It also needs to be done on new brakes to get all the rust inhibitor off the rotors.

The squeak is from the pads chattering in the calipers. Glazing is what causes chatter. The Burn in process puts brake material into the rotors to make them more effective. This makes the brake pressure less for the same braking effect. Less pressure = less heat = less glazing + brake dust.
The vehicle should not be allowed to stop during the burn in. This can cause the pads to leave a chunk of brake material on the rotors which gives a pulse in the pedal and/or steering wheel. if that happens your have to start all over.

To give you an answer. . .no the rotors are fine. They just need to be scuffed and burned in again.

SS

Thanks. I am going back down to my dealership this weekend, and I will have them check the brakes out again, and suggest what you said.

Anytime.

Brake Burn in? That sounds like a terrible thing to do. Material transfer is a major cause of rotor hot spots. I would recommend you do not try to get pad material to transfer to the rotor. I can almost guarantee that will make your pedal pulse, your rotors cool less even and lower your braking capacity.

I did a Google search and no data came up for brake burn in. If I am wrong can someone please post a link that would endorse this process.

Thanks

Cleaner,
you have mail.
It's a very common and needed thing to do.http://answers.yahoo.com/question/in...4133931AAjIqpW

Thanks supersteve,

I am familiar with the brake bed in deals, They are not needed and almost impossible to reproduce with any consistence. TMD friction does not recommend it nor do any of the automakers. New car are also not subject to the process.

I know the web forums are full of different ways to break in brake pads, but honestly I have yet to see any major brake manufacturer, Auto Manufacturer or Dealership take part in the ritual.

So just use the coating on exterior of the brakes? Or what else can you do
to stop the sqeal?

Think about this. . .Do they want to sell you a lifelong part or do they want you to buy another set.

I can feel a difference in the brakes before and after burn in. It's something I have done for many years with no ill effects (other than the smell of burning brakes while doing it).

Think of it as a way to break in the pads in an accelerated and controlled way. Heat cool heat cool heat cool done. It prevents glazing which its the worst case senario for brakes.

Glazed brakes will wear at a highly accelerated rate because they are very ineffecient @ causing friction. This is especially true if the pads are chattering and/or squealing. The noise is the pads vibrating against the rotor. The vibration means they are not making full contact with the rotor @ all times. Less pad to rotor contact = increased pressure for same brake effect = increased wear = more money for the brake manufactures.

For light aircraft it is a required step, to burn in the brakes, after brake replacement. Same brake companies much higher liability.

Just my $.02

Squeak is related to materials, very little else. A recurring squeak can be cured by changing the rotors and pads to OEM compounds, that’s Jurid pads in the front and Textar in the rear, a good Balo, ATE or Zimmerman rotor and 2 new caliper pins and the rubber bushing the pin rides in. Those pins and bushings can wear and cause the caliper to tilt and that is the likely cause if you are using the correct pads and rotors. BMW and TMD Friction spend hundreds of hours testing components to come up with the best blend. When consumers try to improve one area the result is a reduction in performance in another area.

Speaking from my experience, this is the best way to cure the problem, do not use any sprays or other snake oil when you install the pads, mount them dry and be 100% sure the pad shim is in place, that is your buffer between the brake pad “puck” and the caliper frame and piston. The shim will isolate the vibration to the rotor and pad friction surface and not let it transmit to the caliper where the squeak will develop.

Check out this site. It's from Bosch but it explains why "The Cleaner" and I are both correct.

The first section talks about causes of noise. The third section talks about brake break in.

The Burn in I have been talking about is to cure the pads in a controlled way and apply some material to the rotors.

According to Bosch not all pads are created equal.

Enjoy the weekend (if you get one).


SS

oops

http://www.boschautoparts.com/Resour...s/BrakePad.htm


Double OOPS!

Applying WD40, which is a water displacing product that includes mineral oil, to your brakes, is a very bad idea. Brake pads are not designed to be contaminated by oils and still have the proper performance characteristics (friction, durability, etc).

Squealing brakes are caused by the pad vibrating. You can isolate that vibration so that it doesn't carry through the caliper, when you hear it, by using high temperature grease on the ears of the pads where they touch the calipers. There should never be lubricant applied to the friction surface. Never.

thank you, but what are the main causes of pad vibration?
I changed my rotors/pads (used ones) about 500 miles ago and the squelling is still there :(