Had Rotors Machined, Can They Still Be Used? Pic Inside

[No Crust Racing]

Hi guys,

Car is S13 with S15 slotted vented rotors and S15 calipers + R32 GT-R master cylinder - car is track oriented.

Used up the last set of pads so got some new ones and dropped rotors off to be machined. They were heavily grooved but the brake shop said no worries as they were still above minimum thickness, he did mention I might need to have an engineering place touch up one or two slots as the driver side inner was a bit wiped.

The below pic is what I ended up with.

As you can see there's still a very notable groove on the outer edge and the slots are baically gone, this is the "good" one in that it still has "some" slots visible.

He didn't charge me but said to go deep enough to get the groove out would have gone below minimum thickness and that at the moment I can just re-slot them and get another few thousand k's out of them. He didn't seem concerned about the groove and said they end up with that sort of thing on street cars all the times.

What are your thoughts Brake Gurus?

Excuse photo, only have iPhone 3Gs on me at the moment.

Cheers

Edited December 22, 2011 by ActionDan

[No Crust Racing]

It's been suggested that it might be better to just use them as they are and not decrease the strength of the rotor any more by slotting it again, any ideas on what performance loss I might see from running non slotted rotors? I am planning on running brake ducts from the front of the car.

[GTSBoy]

Slots are usually cut to approx the machining limit, so when they're gone, it's a sign that the discs are done anyway. So, just bang them back on, and budget for some new discs soon, rather than spend $$&effort on recutting slots.

[No Crust Racing]

Any thoughts on how much quicker they will go off? I am going to install so brake ducts this time around.

[GTSBoy]

What do you mean "go off"? You talking about the pads going off when you're on the track next time? Slots don't really make any difference there. They're not for cooling so much as to allow the friction created gases and dust to escape from the pad-rotor interface, giving a bit better braking overall, but not really leading to less fade. If you're putting in some ducts to cool them off, they'll probably work a lot nicer next time, with or without slots.

[No Crust Racing]

By go off without slots I'm more so talking about the pads having nowhere to expel gas and debris, which then builds up and can end up giving a warped feel on the rotor.

I've going to use them as is and have got a deal on some new ones too goo to pass up so will keep those for the next set of pads.

[GTSBoy]

I wouldn't worry about it. Brakes never had slots for decades and they still worked.

[No Crust Racing]

Yeah I'm comfortable enough with it to give them a go, if they suck I have new ones as backups.

[gslrallysport]

Depends what pads you're running. Very basic street pads do benefit SLIGHTLY from the cooler pad face created by the slots, but any sort of half decent semi track or competition pad it will make very little difference. Look at the really high end rotors (ala Alcon/AP etc.) and their slots are much much smaller than what comes on DBA/RDA etc.

[No Crust Racing]

Greg I'm running your pads again after being happy with the bang for buck the first time around.

As it turns out I've rigged up some basic brake ducting into the wheel arch area and am going to use these rotors, I came across a good deal on new slotted anyway and bought those but will keep as spares.