for modern brake pads, crossdrilled/slotted won't enhance their performance. really they'd just increase brake dust. if you want to keep oem rotors, have them surfaced so that the new pads dont' wear out too fast.
Rotor's Question
Hi Guys
General, straight to the point question-- For regular road driving, do slotted and/or cross drilled rotors do anything for braking? Or is it just a waste of money?
I do plan on the Hawk HPS pads when its time to change, but should I change the rotors at the same time? And if so....should I go OEM or slotted and/or cross drilled?
Thanks gang.
-Everett
General, straight to the point question-- For regular road driving, do slotted and/or cross drilled rotors do anything for braking? Or is it just a waste of money?
I do plan on the Hawk HPS pads when its time to change, but should I change the rotors at the same time? And if so....should I go OEM or slotted and/or cross drilled?
Thanks gang.
-Everett
1 - 20 of 20 Posts
Sorry but I strongly disagree. While slotted disk are actually bad for the general everyday driver, the crossdrilled brakes will greatly enhance your performance.
The slotted disk are more geared toward [glow=green,2,300]racing[/glow]. When racing and braking excesively, a dew tends to build up, so the slots act as blades that cut that away.
For us normal drivers, that slot will actually just cut away at the brake pad and shorten its lifespan.
While crossdrilled will actually lengthen the lifespan of the pads and the rotors itself, creating a cooler enviornment to work in.
Please look at getting these sort of brakes, that are much more effective and funner. [glow=red,2,300]:klavergreg:[/glow]
The slotted disk are more geared toward [glow=green,2,300]racing[/glow]. When racing and braking excesively, a dew tends to build up, so the slots act as blades that cut that away.
For us normal drivers, that slot will actually just cut away at the brake pad and shorten its lifespan.
While crossdrilled will actually lengthen the lifespan of the pads and the rotors itself, creating a cooler enviornment to work in.
Please look at getting these sort of brakes, that are much more effective and funner. [glow=red,2,300]:klavergreg:[/glow]
Hardly. Cross drilling actually causes you to have less surface area for contact of the pad/rotor and often leads to premature cracking in the rotors. It looks cool, though. With modern pads, your best bet is just stock rotors.
cross drilled rotors do provide more cooling. if solid vented rotors were best then they wouldnt put them on high performance cars like corvettes as stock parts
A quality set will not crack with hard street use. If you have a set that isnt drilled properly, you can bank on it, but anyone reputable, and you will be fine. I bought an excellent set on Ebay for my Vic. I added ceramic pads and synthetic fluid. Stopped soooo much better, and I never got the brake fade that I did before from the weight of the vehicle. It is true that there is less rotor area for the pads, but if the gases are building up behind the pad, then that point becomes null. Slotted/drilled give the escape route for the gases keeping the pads on the rotors. I had less brake dust as well with this combo. On somthing this small, is it something you need.....NO, is it something you want....YES! I wont run out and get them on this car, but when mine wear out, you can bet I will be upgrading. :agbullet:
Heh, the cooling is a myth and I've even seen Brembo cross drilled rotors crack. Here is some good reading about rotors you guys should read.
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
[quote author=kdmxdgt link=topic=69460.msg1219779#msg1219779 date=1172021377]
cross drilled rotors do provide more cooling. if solid vented rotors were best then they wouldnt put them on high performance cars like corvettes as stock parts
[/quote]
if cooling was an issue larger rotors like stock on corvettes are more effective than the holes in the rotors
cross drilled rotors do provide more cooling. if solid vented rotors were best then they wouldnt put them on high performance cars like corvettes as stock parts
[/quote]
if cooling was an issue larger rotors like stock on corvettes are more effective than the holes in the rotors
[quote author=j-so link=topic=69460.msg1219899#msg1219899 date=1172024197]
Heh, the cooling is a myth and I've even seen Brembo cross drilled rotors crack. Here is some good reading about rotors you guys should read.
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
[/quote]
that was a good read!
Heh, the cooling is a myth and I've even seen Brembo cross drilled rotors crack. Here is some good reading about rotors you guys should read.
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
[/quote]
that was a good read!
Yup. I won't lie cross drilled rotors look cool but they don't provide the performance people think. Slotted is really better. Personally I would like to get some slotted/drilled rotors just for the bling factor, lol.
Another issue with cross drilled and slotted rotors is weight. In high performance cars, every ounce of weight matters, so cross drilling allows a reduced unsprung mass, which results in much lower rotational inertia of the wheels, thus better acceleration and deceleration. I think the difference for the 3 will not be at all noticeable. I think they are more for aesthetics (they look cool) than anything else for a car this size.
[quote author=j-so link=topic=69460.msg1219899#msg1219899 date=1172024197]
Heh, the cooling is a myth and I've even seen Brembo cross drilled rotors crack. Here is some good reading about rotors you guys should read.
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
[/quote]
Yeah, good write up.
The only thing is that a larger rotor WILL increase the available braking force, but it is a trade off with weight. Larger radius rotor means the force applied to the rotor is further away from the center of rotation, giving a greater moment or torque about the spindle. That means more effective force.
Heh, the cooling is a myth and I've even seen Brembo cross drilled rotors crack. Here is some good reading about rotors you guys should read.
http://www.scirocco.org/faq/brakes/pulpfriction/poorrotors.html
[/quote]
Yeah, good write up.
The only thing is that a larger rotor WILL increase the available braking force, but it is a trade off with weight. Larger radius rotor means the force applied to the rotor is further away from the center of rotation, giving a greater moment or torque about the spindle. That means more effective force.
[quote author=j-so link=topic=69460.msg1220883#msg1220883 date=1172071483]
Yup. I won't lie cross drilled rotors look cool but they don't provide the performance people think. Slotted is really better. Personally I would like to get some slotted/drilled rotors just for the bling factor, lol.
[/quote]
me too, I've reallllly been considering it because they look so good.
Yup. I won't lie cross drilled rotors look cool but they don't provide the performance people think. Slotted is really better. Personally I would like to get some slotted/drilled rotors just for the bling factor, lol.
[/quote]
me too, I've reallllly been considering it because they look so good.
My observations:
Brakes function by creating friction between the pad and rotor, and where there's friction there's heat. A larger rotor WILL be able to create more friction so this is why big trucks benefit from huge rotors. Small cars don't need huge brakes so the brakes are smaller.
Rotors dissipate heat by transfering heat to the pads, wheel and suspension, and also to the air. The little holes in the rotor don't do much to cool the rotor. Think about how much air is flowing around the inside and sides of the rotor, then think about how much air is going to be going through the tiny holes. I don't think it's effectively increasing the "air" cooling all that much.
Sure you are increasing the surface area of the "heatsink" with holes, but more importantly you are decreasing the "mass" of the brake pad. If the same amount of heat is put into a rotor with a larger mass, it will result in a lower temperature. This is basic physics with mass and specific heat of materials.
With holes and slots you are also decreasing the contact surface of the pad and rotor. This means less friction the more holes added...
A ceramic rotor will be able to create friction, but not get as hot as metal ones. This is why some race cars use very expensive ceramic rotors. No they will not cross drill them, because that will only weaken them.
In order for some cars to compete, they have to drill their rotors to decrease the weight of the rotor and achieve performance like that of somebody using ceramic rotors. This is probably why you may see some race cars with them. It's a compromise of durability and performance.
The bottom line is most companies will not suggest cross drilled rotors for severe or track use because they are weaker than if they didn't have holes. Many companies offer drilled rotors because they look cool, and sell, more so than because they have better performance.
Nascar and F1 don't do it... Not even 1/10th scale race cars.
The lotus elise street car have cross drilled rotors. The lotus elise exige has slotted... You can see how lotus doesn't put drilled rotors on their model that is more tuned for racing.
Brakes function by creating friction between the pad and rotor, and where there's friction there's heat. A larger rotor WILL be able to create more friction so this is why big trucks benefit from huge rotors. Small cars don't need huge brakes so the brakes are smaller.
Rotors dissipate heat by transfering heat to the pads, wheel and suspension, and also to the air. The little holes in the rotor don't do much to cool the rotor. Think about how much air is flowing around the inside and sides of the rotor, then think about how much air is going to be going through the tiny holes. I don't think it's effectively increasing the "air" cooling all that much.
Sure you are increasing the surface area of the "heatsink" with holes, but more importantly you are decreasing the "mass" of the brake pad. If the same amount of heat is put into a rotor with a larger mass, it will result in a lower temperature. This is basic physics with mass and specific heat of materials.
With holes and slots you are also decreasing the contact surface of the pad and rotor. This means less friction the more holes added...
A ceramic rotor will be able to create friction, but not get as hot as metal ones. This is why some race cars use very expensive ceramic rotors. No they will not cross drill them, because that will only weaken them.
In order for some cars to compete, they have to drill their rotors to decrease the weight of the rotor and achieve performance like that of somebody using ceramic rotors. This is probably why you may see some race cars with them. It's a compromise of durability and performance.
The bottom line is most companies will not suggest cross drilled rotors for severe or track use because they are weaker than if they didn't have holes. Many companies offer drilled rotors because they look cool, and sell, more so than because they have better performance.
Nascar and F1 don't do it... Not even 1/10th scale race cars.
The lotus elise street car have cross drilled rotors. The lotus elise exige has slotted... You can see how lotus doesn't put drilled rotors on their model that is more tuned for racing.
this whole thread is VERY informative... sticky maybe?
[quote author=HouRman link=topic=69460.msg1221144#msg1221144 date=1172077284]
My observations:
Brakes function by creating friction between the pad and rotor, and where there's friction there's heat. A larger rotor WILL be able to create more friction so this is why big trucks benefit from huge rotors. Small cars don't need huge brakes so the brakes are smaller.
Rotors dissipate heat by transfering heat to the pads, wheel and suspension, and also to the air. The little holes in the rotor don't do much to cool the rotor. Think about how much air is flowing around the inside and sides of the rotor, then think about how much air is going to be going through the tiny holes. I don't think it's effectively increasing the "air" cooling all that much.
Sure you are increasing the surface area of the "heatsink" with holes, but more importantly you are decreasing the "mass" of the brake pad. If the same amount of heat is put into a rotor with a larger mass, it will result in a lower temperature. This is basic physics with mass and specific heat of materials.
With holes and slots you are also decreasing the contact surface of the pad and rotor. This means less friction the more holes added...
A ceramic rotor will be able to create friction, but not get as hot as metal ones. This is why some race cars use very expensive ceramic rotors. No they will not cross drill them, because that will only weaken them.
In order for some cars to compete, they have to drill their rotors to decrease the weight of the rotor and achieve performance like that of somebody using ceramic rotors. This is probably why you may see some race cars with them. It's a compromise of durability and performance.
The bottom line is most companies will not suggest cross drilled rotors for severe or track use because they are weaker than if they didn't have holes. Many companies offer drilled rotors because they look cool, and sell, more so than because they have better performance.
Nascar and F1 don't do it... Not even 1/10th scale race cars.
The lotus elise street car have cross drilled rotors. The lotus elise exige has slotted... You can see how lotus doesn't put drilled rotors on their model that is more tuned for racing.
[/quote]
and more information on cross drilled versus slotted can be found at http://forums.nasioc.com/forums/showthread.php?s=&threadid=368072
My observations:
Brakes function by creating friction between the pad and rotor, and where there's friction there's heat. A larger rotor WILL be able to create more friction so this is why big trucks benefit from huge rotors. Small cars don't need huge brakes so the brakes are smaller.
Rotors dissipate heat by transfering heat to the pads, wheel and suspension, and also to the air. The little holes in the rotor don't do much to cool the rotor. Think about how much air is flowing around the inside and sides of the rotor, then think about how much air is going to be going through the tiny holes. I don't think it's effectively increasing the "air" cooling all that much.
Sure you are increasing the surface area of the "heatsink" with holes, but more importantly you are decreasing the "mass" of the brake pad. If the same amount of heat is put into a rotor with a larger mass, it will result in a lower temperature. This is basic physics with mass and specific heat of materials.
With holes and slots you are also decreasing the contact surface of the pad and rotor. This means less friction the more holes added...
A ceramic rotor will be able to create friction, but not get as hot as metal ones. This is why some race cars use very expensive ceramic rotors. No they will not cross drill them, because that will only weaken them.
In order for some cars to compete, they have to drill their rotors to decrease the weight of the rotor and achieve performance like that of somebody using ceramic rotors. This is probably why you may see some race cars with them. It's a compromise of durability and performance.
The bottom line is most companies will not suggest cross drilled rotors for severe or track use because they are weaker than if they didn't have holes. Many companies offer drilled rotors because they look cool, and sell, more so than because they have better performance.
Nascar and F1 don't do it... Not even 1/10th scale race cars.
The lotus elise street car have cross drilled rotors. The lotus elise exige has slotted... You can see how lotus doesn't put drilled rotors on their model that is more tuned for racing.
[/quote]
and more information on cross drilled versus slotted can be found at http://forums.nasioc.com/forums/showthread.php?s=&threadid=368072
Ha well that checked me!!!
Thanks, now I can go preach something else that is actually true.
Thanks, now I can go preach something else that is actually true.
Well my 2cents.... I work in a repair shop and deal with this daily. As far as cracking the Cross Drilled... rarely do I see this... I have seen this on Factory Porche rotors, but they have a billion whole drilled very close to each other and some times on the Super Duty or other 1 ton trucks with aftermarket rotors. I have often seen large trucks with factory rotors crack due to sever overheating. I can't remember the last time I have seen auto rotors crack.. As for the pad life of slotted rotors, we have seen just the opposite. extended pad life on the vehichle we equip with slotted rotors. Of course a quality pad has everthing to do with this and should be considered as part of this upgrade. My 3 has the Hawk HPS pads with stock rotors. I have gotten the brakes soooo hot smoke rolls out of the wheels and the rotors have turned blue... and yet they have not cracked...warped the twice in 60K miles. I may try the slots for the track some day but I would put your money in the pads.
Just for a bit of a laugh: whatever performance rotor you end up getting, make sure it's for the rear and not the front - the earlier Mazda 3 seems to do most of its braking in the rear due to the extreme wear rate (see all the rotor wear posts). At 31K miles, my stock front pads and rotors look spanking new and the rear rotors and pads had to be replaced. I think a proportioning valve adjustment is in order ...but that's a dicey thing to mess with.
I think that may be a pad issue... early on I asked about a recall? on the excessive rear pad dust, and the dealer had nothing to say...so I changed out the rears to a DuraLast Gold pad from Auto Zone... Problem solved... I changed them at around 25k or so and the stocks still looked good and no at 60k they still look great .... little to no dust... 
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