drilled/slotted rotors-- direction of rotation

[theheff]

So I installed a set of Bradi drilled/slotted rotors on my 92Q along with full OEM pads and shims. I still get a bit of rubbing noise/roughness when using them, which is probably due to break-in (it's only been about 100 miles), but I got to wondering this: I have seen several sources say that slotted rotors should rotate with the outermost (radially) part of the slot contacting the pad first (during forward motion). Anyone know if this is true or should I switch sides? Wondered if this might cause more noise/wear... Or does it not even matter?

[Q45tech]

Slotted or drilled rotors must be measured [after install] to make sure the radial/axial runout is in spec [0.0028"] otherwise they will make more noise as the holes slots are covered by the pads at differing angles/amounts in different parts of the rotation.

Shish.........Shish .........Shish...........when the wheel is tirned.

[theheff]

Yeah clearly runout is bad, but what about direction of rotation? Also, the venting vanes are non directional so the only "directional feature" is the slot/hole pattern...

[szh]

So I installed a set of Bradi drilled/slotted rotors on my 92Q along with full OEM pads and shims. I still get a bit of rubbing noise/roughness when using them, which is probably due to break-in (it's only been about 100 miles), but I got to wondering this: I have seen several sources say that slotted rotors should rotate with the outermost (radially) part of the slot contacting the pad first (during forward motion). Anyone know if this is true or should I switch sides? Wondered if this might cause more noise/wear... Or does it not even matter?

I have drilled/slotted Bradi rotors with OEM pads too on my 95Q. When I first installed them, I also noted the noise - the general consensus here was that slotted and drilled rotors sound different. The noise wasn't really loud, or bad, just sort of a increased thrum. I got used to it quickly. The brakes work well!

With regard to your "slot contact position on pad" question, I find it difficult to believe that this would make a difference in some way. Not that I know ... but I just don't see any obvious reason for this statement. Do you have more references that I can look at? Do they explain in more detail?

Z

[911/Q45]

My other car has drilled rotors from the factory and the pattern is such that the innermost holes contact the pad first when rotatiing forward. The Skyline brakes on my Q, which are directionally vented, are also oriented so the innermost holes hit the pad first. I'm assuming that slots would also be oriented that way.