Zimmermann cross-drilled rotors

[rbautj]

The dealer says that Zimmermann drilled rotors only come with clockwise patterned drill holes, so when installed they are in opposite direction. Is this true? He said he sold hundreds with no problem. There must be a reason for directional design or just drill them radial. I think that is why it's called "Cross-Drilled" in the first place. Need help to convince me.....
The original undrilled rotors are excellent, but because they are not ventilated, drilled may help on cooling.

[DinanTi]

Hey,

I have the Zimmermen cross drilled rotors and I have not had any problems. I feel that my braking has improved since I got them. They look really good too. Hope I helped you out some. I would definantly get them if I were you.

:evil: Scotty :twisted:

[1996 328ti]

Why would you think your braking has improved with cross drilled rotors?

You would be better off with vented rotors unless your build is +4/98 and you already have them. The biggest factor on braking distance is tires.

And why is cooling important on the street anyway?
You want cooling in track conditions when you are on your brakes HARD repeatedly.

The marketing being cross grilled and grooved is so your rotors don't glaze. One stomp on the brakes is enough to clean the rotors.

If you want them because they look cool, I'll buy that. But you are being mislead if you think there is any significant improvement in braking.

[ClubSport]

The reason for the swoopy drill pattern is vibration and noise. If the holes were all in neat rows, then the sound of your pads going over them would be like rumble strips. They are drilled so the holes overlap. The directional pattern means nothing.

I agree with Steve. Don't get the drilled rotors unless you're going for 'bling' effect. There are also anecdotal problems with pad wear, rotor cracking, etc. Just go to non-drilled vented ones.

[bimmerboi318]

i've had ate powerdiscs slotted rotors on my car for some time now, and i havent noticed anything significant in my braking. well, i definately noticed braking had imporved, but just for the simple fact that i had new pads and rotors. the old ones were shot. this, IMO, is often the case for alot of mods. i put a K&N cone on my car for a while and noticed a difference, but after going back to a clean paper filter i realized the biggest difference i noticed was having a clean filter. but yes, the slotted rotors do look nice :)

[Turbo-ti]

Actually slotted rotors do serve one more purpose other than to look good. They help remove gas build up and pressure from inbetween the pad and the rotor surface for less break fade when you are getting on the brakes hard wheither its once or repeatedly, but they are not needed on daily driven cars..Stock rotors and pads work very well because if youve ever noticed the pad and the rotor wear down together always leaving a new surface to brake upon..We always change pads and rotors at the dealership when we do break jobs if we can..