python

iTrader: (4)

Pulsating brakes start with a localized zone of high temperature in the rotor. The most common cause is uneven friction deposition on the rotor. At colder operating temperatures (less than 400 degrees), brake pads work with abrasive friction, just like sandpaper on wood. At higher temperatures, brake pads transfer a thin layer of material to the iron rotor surface. As the rotor heats up, the primary friction force changes from abrasive friction to adherent friction, i.e. pad material is applied to the rotor and simultaneously sheared and the broken chemical bonds cause a resistant friction force. Most racing pads work using adherent friction, which explains why racing pads don't really stop well under cold conditions or normal street driving.

An example of an uneven friction deposit is pad resin glazing. If you get your rotors hot, the resin from the pad will liquify and glaze on the rotor surface. As the pads rub on the elevated glazed surface, it gets a lot hotter, and the heat is localized in just one area of the rotor. When the temperature exceeds 1150F, the cell structure of the iron changes into hard brittle spots called cementite. These heat spots don't wear down like the normal iron material surrounding it. So the spots become elevated above the rotor surface, and you start to feel brake pulsation. You can try to turn down the rotor, but the cementite nodule is often deeper than the cut, so the brake pulsation just comes back after a few weeks.

python

iTrader: (4)

i don't know what else to do to disprove u..we have gone over this before shmee

Shmee

iTrader: (3)

So what of the copy&pasted ebay quote disproves what I said?
If you go on to read the rest of that article, it agrees with many of the things I stated earlier, so i'm not sure what or how it disproves me.


warp is just another word for distortion like bend or twist. it does not relate to any one specific type of distortion which is why it is used interchangeably in colloquial use when speaking of brake rotors.

http://www.bimmerfest.com/forums/att...3&d=1360837373
http://www.bimmerfest.com/forums/att...4&d=1360837373


I'm not denying material transfer causes pedal pulsation or that it may be the primary issue at hand, simply that any overall deformation of the rotor to a state were the rotor faces are parallel to each other but shifted at a single (or possibly minor double) angle away from parallel to the hub face, can be classified as a warp.

python

iTrader: (4)

either way u look at it the rotors don't warp..period,end of story and argument
quote from you
rotors can and do warp, as can be seen with, thermal imaging, dual dial indicators or even placing rotors against each other.
its simply not true
http://www.stoptech.com/technical-su...nd-other-myths
believe what u want..it makes no difference to me what u believe to be true.

Shmee

iTrader: (3)

Obviously it does matter!

Lack of the Marlboro man doesn't give you the vent needed! :P

PureDrifter

iTrader: (10)

both of you cool it, pose your arguments and lose the jabs at eachother. let the readers decide.

rick1987

iTrader: (1)

Is it possible you didn't break them in correctly?

I was actually a bit worried when I went to do it.

I drove to around 55 then stood on the brakes until about 10mph, then floored it back to 55 and repeated 5 times.

Then I let them cool for a bit and did it again from 40 to almost a slow roll. 5 times.

The entire time I made sure I did not let the car stop, from what the directions said, when the pads heat up they will deposit resin/material to the rotor, and you don't want the rotor to stop and have a uneven layer deposited.



After driving around for a couple days, these brakes brake hard! I'm not even sure if I'm using the rear brakes anymore.

And they grab even harder when they heat up. I have to get used to it.