mark kibort

Well, both, but im a little embarrased that im doing this with the stock deflector vanes. I have a cooling duct in the air dam and then a deflector vane up and down on the lower control arm that guides air to the center cooling vanes and also the inner rotor itself. I probabably should rig some real hoses to the center rotor cooling inlet.

funny thing is, those two pictures are the same rotor. bad cracking only in one spot. the other side rotor looks good, with no edge cracks at all.

mk

DK

kinda suspicious that the bad cracks are on ONE internal vein, not equally across the entire rotor. The rest of the rotor looks great. you ran the orange pads on these rotors - before the black? and one event with the blacks caused this hot-spot?

I tried blacks, but for non-abs I preferred the modulation control of the orange - I'm no expert.

mark kibort

These rotors have seen all pagid blacks from the start. Sears weekend, Laguna weekend and this last weekend at thunderhill. Blacks are fine for modulation. basically they are like the orange, but they dont fade on those very high speed decels. (like going into the corkscrew, or turn 2 at laguna)

It is strange that the cracking follows that one vane

onefastviking

Yet you both already know the answer.

IcemanG17

MK
Since the cracking follows only 1 vein....maybe there was a casting bubble in that vein which caused the crack..... Hopefully a set of new rotors will fix it

Bryan Watts

Ha.

TrackDays247.com

Whoa. Rotors of death, recycle time. Also add a cooling tube to the face of the rotor/caliper junction -

mark kibort

will do. Thanks guys.

what do you think the mode of failure would be if I used this rotor? think it could come apart? its only the outside surface.

anyway, what about solid, flat rotors. anyone race with them? is slotting them really nesessary? thoughts, comments?

thanks

Mark

TrackDays247.com

Slotting should be beveled/angled at a 45-ish within the 'valley', and tapered at the ends.
Slots should be no deeper than the minumum disc thickness, and should not come closer than 4mm or so to the edges.

Mark, that rotor is in horrible condition -

mark kibort

Thanks! do you think a flat rotor can be as effective? If I get a used set, can I just turn it and install if it is just a few thou of turning?

Mk

333pg333

Mark, interestingly I had almost the same result with those OEM 965 rotors and a mix of Pagid Blacks and then some PFC 01s. Big cracks after only 3 meets. Tossed them away and had to get new rotors the same. We're waiting on getting some slotted rotors. Don't think there are any off the shelf ones available? Anyone? I had the solid GTS rotors and suffered spongy pedal. Can't say for sure if it was due to the rotor but I feel confident that the holes are helping with the dissipation of the gases.
Hopefully the slotted ones will be the best of both worlds.
Going to check out your vids now. They're always fun.

mark kibort

Uggg! thats what i was afraid of. soft pedal, too much heat with a flat rotor!
Im thinking of having someone cut slots in them, so based on your experience, I think Ill have to do that!

Thanks,
mk

333pg333

I don't think that would be difficult for you to get done in the US at all Mark. Keep us posted on what you come up with.

mark kibort

OMG, I just took the car out for my usual saturday afternoon drive. IT is clearly DANGEROUS. Its like the worst warped rotors you have ever felt. I changed out the rims to my "B" set and looked at the rotors carefully. Ive never seen cracks like this. they cross the air fents and crack all the way to the inside surface!! somehow when the rotors where hot during the race, I didnt feel much of a problem. Clearly, there is one!
I guess its solid rotors with some cut slots next time!

mk

earlyapex

I had the same cracks on a set of Zimmerman rotors on my 911. I was using Pagid Orange pads with AJ USA air scoops and ducting to the center of the rotors.