Drilled/Slotted/Dimpled?!

[tdurr]

Some good info I found on another forum i surf.



What was wrong with the old ones? ...or did you just buy the new ones for the cool factor of the c/d look?

The reason I ask is because if the old rotors were good (ie. no pulsating pedal upon braking), then they are still true. You can just slap them back on, and with the new pads you'll be back in business and without the shake or any further expenses.

If the new rotors are warped already, there's a slight chance they were slightly off when you got them, in which case it might be worth the try to get them turned. The only thing you have to keep in mind is that every time you get a rotor turned, you're making the material thinner which means it will heat up faster and be more prone to warpage down the road.

As for the argument of cross drilled, slotted, both, or blanks, I've had lengthy conversations with Brembo, Baer, and some very willing and knowledgeable guys over at Willwood, and they were pretty much in complete agreement with these facts:

Cross drilled: This practice was used in racing applications to reduce weight of the rotating masses. It was also done promote better heat dissipation on the old steel rotors with the older (less high-tech) compounds that pads use to be made of. Finally, it was also believed to allow off-gassing of the pads to escape from the contact surface faster instead of acting as a lubrication between the rotor and pad surfaces which would make the braking less effective.

There are disadvantages to consider as well. Cross-drilled rotors are significantly weaker than a 'blank' or solid rotor of the identical material. This has proven itself time and again to cause a pre-mature cracking of the rotor which deems it useless.

Sounds like all positives with not too many negatives right? Well, yes, but things have come a long way since then.

Slotting: These slots cut into rotors will allow the off-gasses to escape, and the slotting can (somehow, but I don't completely understand it) pull the the pad back to the surface of the rotor and promote its 'bite' under heavy braking. Because the rotor surface is only gouged and not drilled through, they are structurally much stronger than the cross-drilled rotors. But because the surface is slightly compromised, they will cause the rotor to wear or warp faster, and because they're making your braking more effective, they will wear the pads a bit faster than a blank as well.

Dimpled: This gives the 'cool' look of cross-drilling without the negative side effects of cracking. However, the dimpling has proven not to do much of anything with regards to anything performance oriented. They just look pretty cool. But again, you're compromising the surface of the rotor, so it too will warp and/or wear faster than a blank.

Blank: While this is far more boring, and less aestetically pleasing than a cross-drilled, or slotted rotor, it does withstand more daily driving punishment than really any other rotor treatment. These will be the least likely to warp. While they will probably not dissipate off-gassing of rotor-to-pad quite as well as the slotted, they will do a damn good job of stopping you on command.

At this point, the materials used in rotor and pads are far superior to what they were when the cross-drilling was the thing to do. The newer rotors are stronger, lighter, and the pads are much less prone to heat exhaustion and can deliver great bite even under abuse. (Now that's providing you pay up for good pads as compared to the economy crap pads/rotors available for dirt cheap.) With nearly all cars (and certainly an even greater percentage of race-applications) the rotors are now 'vented' which means two rotor surfaces with a cavity (vents) between the two surfaces. This hugely helps with heat dissipation and cooling, and in turn greatly extends their life.

So at the end of the day, many cross-drilled rotors may look good, but it's really an older technology that doesn't really have a practical application in race purposes. The slotted would be the way I'd go if I'm racing the car, bearing in mind that my rotors/pads will not last as long, but might be a teensie-tiny bit more effective than blanks.

All that said, I currently have Brembo factory cross-drilled rotors both front and back, and Axxis Metal Master Ceramic pads front and back. I did drive it very hard when I was driving it regularly, and never cracked or warped a rotor. And as for the pads, I'm pretty much sold on using these for the foreseeable future. They actually bite more as they warm up. :dunno:

Anyway, sorry for the rambling, but hope it helps. If not, please disregard.

just thought id post up in here.

[jdmdb8itr]

good info

[Drummerboy]

good to know.

Reps.

EDIT: When I can.

[tdurr]

rep me now or else jordan...

[87 Turbo II]

As cool as this is, I thought it was widely known already?

[swimshark]

Yah dont go with cross drilled. I had a set of rotors only last me 3 months. Yes I did take it to a track day, but my rear rotors had stress fractures completely through the rotor and there were tiny stress cracks on my front rotors fanning out from each hole.

If anything, go with slotted. I do notice that the pads do not glaze as with a blank, but either blank or slotted is your better choice unless you are a hardcore racer and dont mind going through rotors every few months.

[tdurr]

Yah dont go with cross drilled. I had a set of rotors only last me 3 months. Yes I did take it to a track day, but my rear rotors had stress fractures completely through the rotor and there were tiny stress cracks on my front rotors fanning out from each hole.

If anything, go with slotted. I do notice that the pads do not glaze as with a blank, but either blank or slotted is your better choice unless you are a hardcore racer and dont mind going through rotors every few months.


do u go to spsu too?

[swimshark]

do u go to spsu too?

yep. im a Junior in computer engineering. live in the courtyard apartments.

[87 Turbo II]

We should have an SPSU meet next semester.... :ninja:

[swimshark]

yah we could set up an event. have a lot of friends that are into cars. i know most of the cops on campus so i know we cant do anything stupid or they will cut us down quick. just a fun meet in one of the parking lots one night.

[BABY J]

1. Modern performance pads do not gas like 1970s asbestos pads.

2. If you are using the cheapest shit pads you can buy at Vatozone the reduction in pad to rotor surface area by using slotted or drilled rotors is a greater loss than any removal of gases. Furthermore you are a moron if you are using $4.99 lifetime warranty pads and expect any decent level of performance from them.

slots > holes

[Doppelgänger]

These days, some higher-end cars will use cross-drilled rotors to increase rotor diameter and reduce mass. BUT. These rotors, as seen on Porsches, Ferrari etc... and as well as Brembo, use rotors that are cast with the holes in place. This forms the metal grain around the holes and makes them far less prone to cracking. A rotor that has been drilled is weak because holes a drilled into the metal grain which weakens the metal around the holes.

[BABY J]

^^ Yeah - a high end set of CAST brakes costs more than most people's car on here.

[AnthonyF]

As cool as this is, I thought it was widely known already?
I agree. But remember, there are new car enthusiasts coming every single day that do not know this. They feel cross drilled is the ultimate shit w/o doing any research on brand, thickness, material, etc...

-Ant.

[Doppelgänger]

^^ Yeah - a high end set of CAST brakes costs more than most people's car on here.

Tell me about it, I've been looking into replacement Brembo rotors for my brake kit...I don't like to think about what it's going to cost me :(

[Doppelgänger]

I just lol'ed...


They actually bite more as they warm up.


:doh:

[swimshark]

These days, some higher-end cars will use cross-drilled rotors to increase rotor diameter and reduce mass. BUT. These rotors, as seen on Porsches, Ferrari etc... and as well as Brembo, use rotors that are cast with the holes in place. This forms the metal grain around the holes and makes them far less prone to cracking. A rotor that has been drilled is weak because holes a drilled into the metal grain which weakens the metal around the holes.

yep exactly. people try to argue at first that these cars use the drilled rotors but they are cast and not cnc machined.

[claybird]

this is some good info thanks

[speedminded]

I honestly don't see much factual info going on there...actually a majority of it is pretty much bullshit lol!

[speedminded]

Originally Posted by markmdz89hatch
What was wrong with the old ones? ...or did you just buy the new ones for the cool factor of the c/d look?

The reason I ask is because if the old rotors were good (ie. no pulsating pedal upon braking), then they are still true. You can just slap them back on, and with the new pads you'll be back in business and without the shake or any further expenses.

If the new rotors are warped already, there's a slight chance they were slightly off when you got them, in which case it might be worth the try to get them turned. The only thing you have to keep in mind is that every time you get a rotor turned, you're making the material thinner which means it will heat up faster and be more prone to warpage down the road.As long as they still meet factory spec upon turning they are just fine. Remember the orange highlighted for later.


As for the argument of cross drilled, slotted, both, or blanks, I've had lengthy conversations with Brembo, Baer, and some very willing and knowledgeable guys over at Willwood, and they were pretty much in complete agreement with these facts:Seriously doubtful.


Cross drilled: This practice was used in racing applications to reduce weight of the rotating masses. It was also done promote better heat dissipation on the old steel rotors with the older (less high-tech) compounds that pads use to be made of. Finally, it was also believed to allow off-gassing of the pads to escape from the contact surface faster instead of acting as a lubrication between the rotor and pad surfaces which would make the braking less effective.

There are disadvantages to consider as well. Cross-drilled rotors are significantly weaker than a 'blank' or solid rotor of the identical material. This has proven itself time and again to cause a pre-mature cracking of the rotor which deems it useless.

Sounds like all positives with not too many negatives right? Well, yes, but things have come a long way since then. This just contradicted exactly what was said about turned rotors above...less mass equal more heat right? So how on earth is removing mass by cross drilling going to dissipate heat? Cross drilled rotors ACTUALLY operate hotter than an identical spec blank because they have LESS mass. Cross drilling has never been done legitimately to reduce weight, it was solely down because of out-gassing created from the materials brake pads were made of YEARS ago. Today those gases are not nearly as present until they are overused and overheated.


Slotting: These slots cut into rotors will allow the off-gasses to escape, and the slotting can (somehow, but I don't completely understand it) pull the the pad back to the surface of the rotor and promote its 'bite' under heavy braking. Because the rotor surface is only gouged and not drilled through, they are structurally much stronger than the cross-drilled rotors. But because the surface is slightly compromised, they will cause the rotor to wear or warp faster, and because they're making your braking more effective, they will wear the pads a bit faster than a blank as well.The slots DO NOT IN ANYWAY create more bite of a pad. They simply keep the surface area clean reducing the glazing effect that happens on overworked pads. If the pads are spec'd properly for the application they will not be overworked and no need for slotting.


Dimpled: This gives the 'cool' look of cross-drilling without the negative side effects of cracking. However, the dimpling has proven not to do much of anything with regards to anything performance oriented. They just look pretty cool. But again, you're compromising the surface of the rotor, so it too will warp and/or wear faster than a blank.Yep pretty much all true there. Marketing scheme, the look without as many negative effects lol!


Blank: While this is far more boring, and less aestetically pleasing than a cross-drilled, or slotted rotor, it does withstand more daily driving punishment than really any other rotor treatment. These will be the least likely to warp. While they will probably not dissipate off-gassing of rotor-to-pad quite as well as the slotted, they will do a damn good job of stopping you on command.Bingo. BUT again, if the pads are properly spec'd then out-gassing will never be an issue.


At this point, the materials used in rotor and pads are far superior to what they were when the cross-drilling was the thing to do. The newer rotors are stronger, lighter, and the pads are much less prone to heat exhaustion and can deliver great bite even under abuse. (Now that's providing you pay up for good pads as compared to the economy crap pads/rotors available for dirt cheap.) With nearly all cars (and certainly an even greater percentage of race-applications) the rotors are now 'vented' which means two rotor surfaces with a cavity (vents) between the two surfaces. This hugely helps with heat dissipation and cooling, and in turn greatly extends their life.Yes, material is more important than anything.


So at the end of the day, many cross-drilled rotors may look good, but it's really an older technology that doesn't really have a practical application in race purposes. The slotted would be the way I'd go if I'm racing the car, bearing in mind that my rotors/pads will not last as long, but might be a teensie-tiny bit more effective than blanks.Cross-drilling has zero use in any race application....except maybe in carbon composite brakes. What's this guys race background again?


All that said, I currently have Brembo factory cross-drilled rotors both front and back, and Axxis Metal Master Ceramic pads front and back. I did drive it very hard when I was driving it regularly, and never cracked or warped a rotor. And as for the pads, I'm pretty much sold on using these for the foreseeable future. They actually bite more as they warm up.

Anyway, sorry for the rambling, but hope it helps. If not, please disregard.Really? Brakes work better once they warm up? Who would have ever thought?!!! :facepalm:

[Gabe]

ive had cross drilled slotted and dimpled rotors on my car for the past 2 years now without any issues whatsoever . BREMBO FTW!

[Doppelgänger]

Cross drilling has never been done legitimately to reduce weight, it was solely down because of out-gassing created from the materials brake pads were made of YEARS ago. Today those gases are not nearly as present until they are overused and overheated.



Yes and No. Like you said, old pad compounds gassed and original cross-drilling reduced that effect. These days, many of the larger high-performance rotors are drilled to help reduce weight and to help with wet braking.

I think I can understand the explanation of heating up fasterand more heat dissipation. I conclude that he means that the rotors will warm up faster due to the reduced mass, and because of that reduced mass, they cool down faster (with proper ventilation of course). Is this true? I dunno, but in theory it seems to have merrit.

[speedminded]

Yes and No. Like you said, old pad compounds gassed and original cross-drilling reduced that effect. These days, many of the larger high-performance rotors are drilled to help reduce weight and to help with wet braking.

I think I can understand the explanation of heating up fasterand more heat dissipation. I conclude that he means that the rotors will warm up faster due to the reduced mass, and because of that reduced mass, they cool down faster (with proper ventilation of course). Is this true? I dunno, but in theory it seems to have merrit.Yes they would get up to operating temperature faster but they would also operate at a hotter temperature because it's reduced mass is doing the same work as a blank would.

There is a quote somewhere from the current or past Brembo president stating that cross drilled rotors is a cosmetic feature and does not offer better performance, it's only lighter.

[tdurr]

Yes they would get up to operating temperature faster but they would also operate at a hotter temperature because it's reduced mass is doing the same work as a blank would.

There is a quote somewhere from the current or past Brembo president stating that cross drilled rotors is a cosmetic feature and does not offer better performance, it's only lighter.


but yet, along with the less weight part arnt pro racers always lookinf for ways to "reduce weight"???:rolleyes:

[RUFFIAN]

People are much better served upgrading to steelbrake lines and good pads.:2cents:

[tdurr]

People are much better served upgrading to steelbrake lines and good pads.:2cents:

slotted rotors are the coolest! :D

[speedminded]

but yet, along with the less weight part arnt pro racers always lookinf for ways to "reduce weight"???:rolleyes:Show me a single RACE CAR with cross-drilled rotors.


Let's start with F1.

http://images.motortrend.com/photo_gallery/112_0702_10z+f1_driving_contest+brakes.jpg

http://www.autoevolution.com/images/news/how-f1-brakes-work-6936_3.jpg

http://i.pbase.com/u16/nogaroblue/large/38950218.2005F1carrearbrake2.jpg


Nope.



How about C6R brakes?

http://image.vetteweb.com/f/9003510/vemp_0709_07_z+chevrolet_corvette_C6R+brakes.jpg

Nope, but if you're lucky you might see steel rotors with j-hook grooves...

http://image.motortrend.com/f/motorsports/corvette-racing-debuts-next-generation-zr1-based-c6r-racecar-for-alms-gt2-class/29258592+w750/corvette-c6r-brake-disc.jpg


How about Flying Lizard's 997RSR ALMS car?

http://upload.wikimedia.org/wikipedia/commons/2/2c/Flying_Lizard_997_Jacked.jpg

File 404 Error. Cross-drilled rotors not found...

http://forums.pelicanparts.com/uploads15/ALMS+LBGP+4+14+2007+997RSR+Flying+Lizard+brake+rot ors1250111347.jpg



How about a ALMS e92 M3?

http://www.europeanautosource.com/images/vendors/apracing/sebring_wdwt_monday_278_2650x1600.jpg

http://www.europeanautosource.com/images/vendors/apracing/sebring_wdwt_monday_220_2650x1600.jpg


Cross-drilled rotors are a JOKE. It's purely a marketing scheme and nothing else.

Stock e92 M3 "performance" brakes vs. AP Racing BBK.
http://www.m3post.com/forums/showpost.php?p=5309868&postcount=206

Want to lose weight? Get a real caliper. Non-drilled rotors and still 10lbs lighter ;)

[yerrow]

truth, thats why i just ordered blanks with my 4/2 piston calipers

[ej1boy95]

i have drilled and slotted

[tdurr]

blah blah blah blah blah
some cool pics
fancy link
:blah::blah::blah::blah:


lulz. u took the bait. :ninja:

anyways i got powerslot rotors :ninja: