I have a fairly new set of slotted rotors that warped at the track last time. Third time to the track on this set with some autocross thrown in for good measure. Originally I thought it was just pad transfer, but I removed cleaned and replaced...still pulsating pedal.

How much is too much to turn? What amount of runout is acceptable to remove?

The rotors are currently right at the 32mm maximum. So, I have some wiggle room.

I realize they may warp again, but I have my $100 PCNA certificate too. I think my next set of rotors will be Porsche parts. I'm not overheating my brakes any more and the aftermarket rotors still warp.

 

Go to your local brake shop they should have specs on "machine to" and "discard measurements".

 

Anymore I think turning is a false economy, unless you can DIY. I've read that turning may only exacerbate warping, since you make the surface straight but the thickness of the material is now all over the place.

I'm running OEM Zimmerman rotors (from Vertex, of all places), they've had about 8-10 track days and lots of street use on them with no problems.

 

Joel.. our rotors are one of the best bargains as far as parts, thay are less than $100 a piece and easy to change. OEM stuff is available without paying Porsche prices. Try Paragon, forget about the slots.. Since we've got the awesome MO30 brakes the slots are overkill. Sure, they look good, but I've run with extremely fast company on Mid-Ohio (A group) with stock rotors and hawk blues and enjoyed flawless eyeball-popping brakes all day, all weekend, all season. Sure, you may need another set of pads and rotors after 10 DE events..but that could take 5 years. I suspect the quality of your slots if you warped them.. maybe too soft of a pad was the culprit. (got too hot) Use my formula, bleed before track days, swap back to performance friction for the street, and enjoy the best brakes out there short of a GT2. Forget about turning.. OEM rotors are cheap!

 

Thanks, Dan.

I think I am going to go with OEM or Porsche rotors and rebuild the calipers. I'm either going to try Hawk Blues or PFC 97s.

I pressure bleed prior to each event, change pads from the street metal masters, and always make sure the pedal is good prior to heading out...

 

That sounds good, Joel. There should be no difference between the OEM and Porsche rotors. Rebuilding the calipers can't hurt. I think you will love the braking power of hawk blues, I'm quite hard on mine and have never had a problem, except dust and rotor wear.. but that's the price you pay for "hand of god" stopping power. Have you ever been up to Mid-Ohio?