850 Rotors, Drilled or Slotted?

Post by **polskamafia mjl** » 15 Oct 2009, 15:05

I've heard many people say that drilled rotors tend to crack, where as slotted do not and help enhance braking. What are your opinions about the matter?

Post by **Ozark Lee** » 15 Oct 2009, 16:10

I have drilled rotors, front and rear, on all 3 of my 850s. No problems with cracking and they have not yet warped. They look kinda cool. I bought them from an outfit called UC Auto Parts in Canada off of eBay for $150.00 per set.

They do make a funny "whirring" noise when you get on them hard from highway speeds.

I think MIJ runs slotted rotors on his car and he can speak for them.

...Lee

Post by **polskamafia mjl** » 15 Oct 2009, 20:39

Thats good news because on FCP I can't find any slotted, just drilled zimmerman's.

Post by **MadeInJapan** » 17 Oct 2009, 08:40

Mine are slotted and drilled and have held up nicely without cracking, etc. I got mine on eBay and are coated so they don't rust on the untouched surfaces. I think that both however is over-kill. They look nice but really, you lose some surface braking area when there is so much of the rotor cut away- so not really any better braking. If I had it to do over, I would probably just go with slotted.

Post by **polskamafia mjl** » 17 Oct 2009, 18:41

Ok, thanks for the responses guys.

milesursogood · Post by **milesursogood** » 21 Jul 2011, 22:32

Ozark Lee wrote:I have drilled rotors, front and rear, on all 3 of my 850s. No problems with cracking and they have not yet warped. They look kinda cool. I bought them from an outfit called UC Auto Parts in Canada off of eBay for $150.00 per set.

They do make a funny "whirring" noise when you get on them hard from highway speeds.

I think MIJ runs slotted rotors on his car and he can speak for them.

...Lee

ozark - did the "whirring" noise persist throughout the life of the rotor & pads? or did it eventually stop once the pads are broken in? if so, how long did it take. do you still have the same drilled slotted rotors that you posted or installed in 2009? i recently installed new drilled slotted rear brake rotors w/ organic pads. i do hear "whirring or purring" noise every time i step on the pedal. it's been persisting now for a couple of weeks. the direction of the rotors are correct. i looked thru the wheels & see not scratches or any gouge on the outside surface of the rotors. can you advise?

zhenya · Post by **zhenya** » 22 Jul 2011, 06:10

That's a characteristic of drilled rotors. They are known to be noisier than plain rotors - you are just hearing the pads pulsing over all those holes.

Post by **850 LPT** » 22 Jul 2011, 07:03

polskamafia mjl wrote:Thats good news because on FCP I can't find any slotted, just drilled zimmerman's.

I have these on mine and they held up really well. They have about 60k on them right now and they are just starting to go (warp). One thing I would recommend doing if you have bigger wheels is to paint the hub area with silver brake caliper paint. Otherwise they will start rusting the minute you put them on, and there is nothing uglier than having nice wheels and rusty looking brake discs.

milesursogood · Post by **milesursogood** » 22 Jul 2011, 07:43

zhenya wrote:That's a characteristic of drilled rotors. They are known to be noisier than plain rotors - you are just hearing the pads pulsing over all those holes.

yes, it's kinda pulsing or pulsating noise. it is possible that it's the pads pulsing over all the holes. however, i have similar drilled slotted rotors (vented) rotors on the front brakes that has never made this noise, and it's been a year old now. is it b/c they're vented unlike the rear rotors that has solid wall thickness?

Post by **polskamafia mjl** » 22 Jul 2011, 09:15

850 LPT wrote: I have these on mine and they held up really well. They have about 60k on them right now and they are just starting to go (warp). One thing I would recommend doing if you have bigger wheels is to paint the hub area with silver brake caliper paint. Otherwise they will start rusting the minute you put them on, and there is nothing uglier than having nice wheels and rusty looking brake discs.

+1 On painting them before installing them.