motopokep

Just ordered sport performance low-dust front and rear brake pads from Bavarian Auto. I have have 80,000 miles on my 2004. My buddy said I should also change the rotors as european rotors do not get filed and sanded as well as american and japanese. He said rotors get sanded and filed to be straightened out when putting on new break pads. I've already spent close to $300 on brake pads. Rotors will set me back another $400. How can I tell if my rotor is bad? I imagine I should measure its thickness, but how thick should a good rotor be?


By the way, the i-drive says I have another 3,200 miles before having to change the rear pads and at least another 15,000 miles before changing the front ones. But I'm changing them anyway as I hear a screeching noise every time I break, which I would imagine, means that somewhere a pad is eaten, right?

Thanx.

AlwynMike

As long as there are no serious grooves in your rotors, just check for thickness. The minimum thickness depends on your exact model, so I can't help with numbers.
My 530d needed new rotors at 45000 miles - and I'm not a hard driver (very often!). Others will need rotors at more than twice that mileage, so the only option is to get the micrometer out and measure them.

Here in europe, generally, the only time rotors get skimmed is in the case of a previously warped one, and that is very rare indeed. There should be no necessity to "have them trued up" because if they aren't wobbling under braking, then they are true, and new pads won't make the slightest difference to that. At aftermarket European prices, it's not that much more expensive to replace a standard rotor than to have it skimmed. There are machines that will skim the rotor on the car, but the only proper way to do it is off the car, so any play in the wheel bearings is not a factor.

As for your squealing, that won't be pads worn down to the metal, because the pad wear sensor will have picked that up and told you that the pads are due for a change now, rather than in 3200 miles. The wear indicator is a complex calculation based on braking force and number of applications, and is therefore only an approximation. If the physical sensor on your pad should contact the rotor, your miles left will drop down to zero immediately, and then display negative mileage as you drive further.

Mike