Rotor questions

[ahlem]

Has anyone had cross drilled rotors refaced successfully? I am evaluating whether to try it for $25.50 for both before I spring for a set. These are for the front of my 535. Second question, if I do my normal replace rather than resurface, is there a preferred reasonably priced source? I'm at about $159 for the pair, if I recall correctly, from Bavarian Auto. There is currently some rust crud in the cross drilled holes that would need attention before I resurface. Your profound intellectual response is requested rather than flaming wacko-ness. Oh wait, this isn't the e30 board. We are more civil.

[Tiger]

I had crossdrilled rotors on my older car for about 8 years. I did have it shaved when the rotor warped a little. It is not worth shaving crossdrilled rotors... it will warp not too long afterward again. Just like any rotor... once cut, too easy to warp.

First, it is a pain in the neck to find someone who will shave a cross drilled rotors... many are scared. Second of all, when you do find one to do it, it is not worth it... will warp soon again.

I don't miss cross-drilled rotors anymore since Ate came out with their Powerdisc... now Premium One. I highly recommends Premium One slotted rotors.

[BMW4LIFE]

I had crossdrilled rotors on my older car for about 8 years. I did have it shaved when the rotor warped a little. It is not worth shaving crossdrilled rotors... it will warp not too long afterward again. Just like any rotor... once cut, too easy to warp.

First, it is a pain in the neck to find someone who will shave a cross drilled rotors... many are scared. Second of all, when you do find one to do it, it is not worth it... will warp soon again.

I don't miss cross-drilled rotors anymore since Ate came out with their Powerdisc... now Premium One. I highly recommends Premium One slotted rotors.

+1 on the ATE

I have them and LOVE THEM!

Saved my life (well from an accident that is) handful of times! =D

[philbyil]

Had them on for years and they work REALLY well with EBC Redstuffs :) !

[ss2115]

Cross drilled rotors can be machined just like any other rotor, but they have a bad reputation of cracking out from the holes.
The trick is that the edges of the holes have to be radiused out again to do the job properly and prevent the cracking.

A lot of dedicated enthusiasts will only buy cross drilled rotors if they were cast with the holes - like Porche rotors, as they don't crack and are stress relieved.

Cheaper rotors are made and then drilled afterwards and the holes often relieve the inbuilt stress by cracking even from new.

I'd agree fully that slotted rotors are a better buy.
They clean the brake dust out from between the pad and rotor for better grab, and the slot edges keep the pads clean by skimming them.
The downside is faster pad wear usually, and often increased noise under braking but this can be a poor match between pad and rotor material and often changing to a different pad will reduce/remove it.

[bubba966]

These are for the front of my 535. Second question, if I do my normal replace rather than resurface, is there a preferred reasonably priced source? I'm at about $159 for the pair, if I recall correctly, from Bavarian Auto.

For good rotors at better prices.
http://www.zeckhausen.com/BMW/E34.htm

And I wouldn't bother with drilled rotors. Too often they crack in street use. And I'd only do slotted rotors if the slots don't go all of the way out to the edge of the rotor. Slots to the edge will crack the rotors.

Really is no need for slots or drilled rotors in street use. Good blank rotors and decent pads are all you need.