Grinding when stopping? HELP!

[cfraser]

1

[bimmerboi318]

If it were my car, I'd replace the front pads and maybe rotors if necessary, take the caliper slides out, clean and lube them, put it back together and see what it does. Also check to see that the wear sensor is intact. It sounds like you may have a caliper sticking on the side with uneven pad wear. Make sure the slides are lubed and everything is free of rust and excessive crusty dust buildup.

[Guy Massey]

I am surprised you can find nothing wrong with the pads. A grinding sound is a sure sign that the back of the pads are touching the disc.

If you are absolutely sure the pads are OK then something else must be touching the disc when you brake. There is the slightest chance that something has got caught between the pad and the disc but it's unlikely.

I would replace the pads but whilst doing so I would check that nothing has slipped or broken that may be causing the noise.

[///M318ti]

ive got the same problem i dont know what it is........ and i just changed rotors all around with crossdrilled rotors and new pagid pads and i dont know what is wrong......... what im thinking it is, is that its the guide pins and i probably need to lube them and making my calipers stick......... if anyone else has an idea let me know

[aceyx]

could be glazing. how old are the pads, and were they properly broken in?

[///M318ti]

glazing................ how am i supposed to break them in............ how do i fix that? :?

[GDB]

glazing is when your pads get really hot and they form a smooth, thin film over the top.
To break in pads, you will want to do break, starting easily just incase something didn't get put back together right, and graduating to really hard stops. For rotors you want to do several very slow, smooth stops to break them in.

[aceyx]

glazing happens when the compound hasn't yet stabilized, and silicates in the friction material rise to the surface and due to high heat, essentially turns into glass. if you remove the pads and they look shiny, that's your culprit.

to fix the problem, use emery paper and rough up the surface until the glazing is gone. reinstall pads.

every pad has a different break-in procedure but generally: bring the car up to 25 mph. brake slowly and gradually over 2/10 mile before coming to a stop. get up to 25 mph again, and drag (ride lightly) the breaks for about half a mile. then do the gradual breaking procedure again.

for the first week, try to stay away from panic stops.


basically you want to heat the compound up slowly and evenly over time, so that the individual materials in the friction material even out. it's similar to heat-cycling new tires for optimum grip.