Machining slotted rotors
 

Well, since the Cage Hell section revived... I"ll revive this one.

I have slotted rotors that have warped from the car sitting. Anyone have experience or suggestions on the best means to fix my issue - other than replacing them?

How do they warp from sitting? I've never heard of that!? According to how warped they are and how much thickness is left, I would think any brake shop should be able to turn them. I've had drilled rotors turned. I wouldn't think slotted would be that much different as long as they take their time.
A machine shop equipped with a grinding attachment for a lathe could definitely do it if it can't be turned conventionally.

I was told it was because the material of the pads versus the material of the rotors cause a little magnetism so when it sits, the pads stick to the rotors and they end up "warped".

My old rotors and brakes (OEM) did the same thing. I was hoping a different combination would help but not so much.

I didn't see why they couldn't be machined, if the shop goes slow but just curious if anyone else had experience with that.

By any chance, was the parking brake engaged during this period of sitting? It is possible when the car was parked, the rotors were hot and if the pads were allowed to stay in contact with the rotor they would have pulled the heat from that spot and could in theory cause warpage. I'm not buying the magnetism theory.

Parking brake would have been engaged but wouldn't that only explain the rear rotors being warped, not the front ones?

Interesting. There is some mysterious mojo afoot! My only guess is since it sat for a while, you've now experienced what it was doing before but, you didn't notice it because it was a gradual change whereas now, you're stepping into the full effect all at once.
I swapped vehicles with my Niece once. I had a F-150 Nite and she had a Mustang. We drove each other's vehicle for a few days. When we swapped back, we each thought the other had broken the other's clutch! My truck had such an easy clutch and her Mustang was incredibly stiff. When we got into each other's vehicles, we didn't know what to expect so, nothing was a surprise. However, we adapted to them quickly and when we got back in our own vehicles we immediately noticed the difference because it was sudden and we had preconceived notions about how they were even though we were wrong.
That's my best theory! It helps you in no way but, it's all I've got! :D

No, I know 100% sure that they were fine before I left - they were basically brand new. Another person drove the car as well. Then after I returned, they weren't smooth and have gotten progressively worse. I know the tires and road make a difference too as some times they feel worse than others. They are warped regardless of why or how. I made a call today and will make a few more to the machine shops to see who can do it for me.

Good luck! If all else fails you could always check the net for new ones. You might get lucky and get a new set for as cheap as turning the old ones.

Just an update. I took my car to the dealer for some other maintenance work and they were able to machine my rotors. I figure they get in WRX and STI's with drilled and/or slotted, so surely they could do mine. Smooth as silk, so very nice to press the brake and not shake to death.

Sweet! A friend just bought a 1989 Virago 250 and the front rotor is so warped it's like a pogo stick when you get on the brakes hard! Not sure if there's enough there to turn down.