1981TA

iTrader: (7)

I ordered a set of Powerstop high carbon track day rotors for Corvette C6 Z51 from Summit, with the idea that I'd be getting rotors that will be up to HPDE use. They arrived fast enough, but the parts themselves appear to not be ready for track day use.

How can I tell?

The OE stock rotors have a basic flaw that comes from GM being cheap: even though the cooling vanes are directional, they only make one side, in a sense putting two driver side rotors in a pair. The PowerStop Rotors have the same issue, which makes me question if they have a carbon content that differs at all from OEM castings--are they simply machining GM blanks and adding a nice coating?

Correct me if I'm wrong, but I think the vane design results in the passenger side rotor being improperly set up to shed heat: as the car moves forward, the backwards-facing vane works against the air flowing outward. That side heats up pretty severely (especially when a car has cooling ducts designed to push the air from the center-outward--the air essentially stays static).

In this picture you will see one of the Powerstop rotors sitting with an OE rotor that just came off my car. The old rotor lasted a solid two years of combined street and autocross use without any appreciable wear. Last week, I had a HPDE event, but the two-piece Racing Brake rotors I normally use were past their minimum thickness (after aprox. 20 track days, four sets of pads and one cut) and I had to "make do" with my street rotors.


This passenger side rotor, when subjected to HPDE conditions, lasted two 20 minute sessions before it cracked and I'm afraid that the PowerStop rotors will do the same, given the similar design. All that said, now that theres a few weeks before my next HPDE, I will likely have another set of RB hats, and these will be street / Auto-X only.

But still, the question persists: Can someone allay my fears on the heat issue? Seriously, why pay a premium for the appearance of HPDE readiness when under the pretty exterior, I suspect there is zero appreciable performance difference from OEM blanks? Here are the rotors I got:



I'm fully prepared to be schooled on this (and in fact hope I will be).

smitty2919

Valid points...I would be calling them for sure knowing how you use the car. 80% of the people buying these are going for looks only and don't pay attention to the vanes.

MAYBE QC sucked that day and someone mislabeled them? Even the pattern of the slots/holes are identical. So one side you have the slots "cutting into the pad" while on the other side they are "wiping" the pad. I would send them an email with those pics then follow up with a phone call to speak to someone.

Other companies I would call is Stop Tech...Wilwood...Baer

*goes outside to look at my own car with BrakeMotive rotors*
My rotors both "cut into the pads" on either side. So I could flip them to "wipe the pads" instead, but I can't tell if I have directional vanes or not.

79_T/A

iTrader: (1)

They drilled so close to the outer edge of the rotor, they will crack during track day use no matter what directions the vanes are going.

smitty2919

That last out hole looks a bit odd...spaced out that far. Why not find some non slotted non drilled but directionally vaned rotors?

1981TA

iTrader: (7)

My preference would have been for slotted, non-drilled, but such an animal doesn't appear to exist at this price point ($200 or less a pair, delivered). I do have a set of Racing Brake ring replacements on the way, so the "extreme use" rotors will be back in play. I also emailed PowerStop and got no response. Next step is reaching out to Summit, who has been very accommodating in the past.

it just bugs me to see someone appear to be pulling a fast one, especially on something so central to safety.

SlasherVRGR

iTrader: (1)

The pattern is mirrored if you look closer. They're def opposite side for the actual drilling and slotting.