BMW brake pad contact with disc

[dave144]

I changed the discs and pads on my BMW 330i msport (mintex pads, pagid discs) and after 2000 miles you can see that the pads on the front are not engaging all the surface of the disc as there is corrosion on the outer rim of the disc. The rear is fine.

Is this normal? I know the pads are the correct ones as they are bigger than the rest of the 3 series range.

[mk2 24v]

how big is the ring of no contact for the pads? most vehicles have the disc protrude form the edge of the pads anyway

[dave144]

i'd say about an inch ring untouched by the pad. Just cannot understand why the rear isn't the same if its "the norm"

[mk2 24v]

an inch

that sounds a tad too much! are the pads that were in there the same as the ones now fitted? sounds like a case of the wrong pads supplied to me

[dave144]

I thought something was amiss, I checked the pad box before I fitted them and it said it covered quite a few models i.e z3 etc. I'm guessing the previous pads were oe stuff.

[Mr2Mike]

You sure the calipers don't have sticking sliders? (assuming the car has sliding calipers rather than opposed piston). If they do then the whole caliper twists when the brake is applied and you end up with this symptom.

[dave144]

mk2 24v said:

an inch

that sounds a tad too much! are the pads that were in there the same as the ones now fitted? sounds like a case of the wrong pads supplied to me

I wouldn't think they were the wrong pads or they would not sit in the carrier?

As for the sliders, they were coated in grease before fitting?

[mk2 24v]

they may well fit, but not have the right size friction material area

had plenty of choices of pads to fit in the years ive been working, and there are some that do fit in the carriers but arent the right choice

do you still have the old pads that came out to test back to back with the new ones?

[dave144]

Should still have the old pads knocking around, from experience it's always worth keeping hold of the old ones.

[stevesingo]

Try using the brakes harder. If the pads are the same shape as the OE pad, then what I suspect is happening is that you are not applying enough pressure to the pads for them to fully engage with the full disc width.

Unfortunately, once this has gotten bad, no amount of hard braking will clean up the discs, as the abrasive rusted area wears the pad away.

If it is not too bad, try doing several high speed (100+) decelerations down to about 30. It might be enough to clean them up.

Steve