Slotted vs. Cross Drilled
01-13-2002, 07:22 AM
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Slotted vs. Cross Drilled
Which is better Slotted vs. Cross Drilled rotors. What is the difference? What is the best after market kit, APR, Bremmo, Big Brake Kit?? What pads are the best for street use? Are they hard to install? Any thoughts will be great.
Manity
Manity
01-13-2002, 08:28 AM
#3
slotted tend to last longer unless the cross drilled are stress relieved.
Even then, the holes tend to cause cracking over time.
Cross drilled does work very well on the track. Slotted works well, but not quite a match for drilled - doesn't seem to have the cracking issue.
Cross drilled does work very well on the track. Slotted works well, but not quite a match for drilled - doesn't seem to have the cracking issue.
01-13-2002, 09:10 AM
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For maximum performance, and where cost is not a consideration ...
... the Williams F1 car used slotted, not drilled, cast iron rotors for qualifying in the '99 Austrian GP. Compared to the "normal" F1 carbon brakes, the superior pedal feel provided by the cast iron rotor in the multiple short 3-lap sprints of a qualifying session was considered worth the weight penalty. [Cast iron rotors have not been used in a F1 race since 1985.]
In our 990 lb Formula Continental, we do use drilled rotors, but for the weight savings; and as you can see in the photo, we remove as much metal as possible.
<img src="http://pictureposter.audiworld.com/17157/drilled.jpg">
The holes are all chamfered to minimize cracking; but as April points out, at the end of a season these rotors must be replaced because of the cracks that initiate at the holes.
IMHO, drilled rotors on a street car are only useful for cosmetics, in spite of Brembo's use of drilled rotors on Porsches. They don't provide any advantage over slotted rotors and are prone to cracking.
In our 990 lb Formula Continental, we do use drilled rotors, but for the weight savings; and as you can see in the photo, we remove as much metal as possible.
<img src="http://pictureposter.audiworld.com/17157/drilled.jpg">
The holes are all chamfered to minimize cracking; but as April points out, at the end of a season these rotors must be replaced because of the cracks that initiate at the holes.
IMHO, drilled rotors on a street car are only useful for cosmetics, in spite of Brembo's use of drilled rotors on Porsches. They don't provide any advantage over slotted rotors and are prone to cracking.
01-13-2002, 09:19 AM
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My thought..."What are you going to do with the car" ?
I think the answer is going to be cross drilled is a waste of time and money for you but that is just a guess.
I needed to do my brakes and upgraded to slotted rotors in front and Rofren pads all the way around. I had to do the brakes and took the money I saved by doing the work myself and put it into a slight upgrade.
<img src="http://pictureposter.audiworld.com/12414/driverfront.jpg">
I needed to do my brakes and upgraded to slotted rotors in front and Rofren pads all the way around. I had to do the brakes and took the money I saved by doing the work myself and put it into a slight upgrade.
<img src="http://pictureposter.audiworld.com/12414/driverfront.jpg">
01-13-2002, 09:38 AM
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Some data. :)
<center><img src="http://www.imagestation.com/picture/sraid28/pf2a907fa5db87308704b4ad449b77f23/fe008c8f.jpg.orig.jpg"></center><p>Slots are for keeping the pads biting nicely. It is for race cars. Rotors after an F1 race are thrown away. Porsche and Ferrari use crossdrilled because the holes vent the steam from environmental moisture that accumulates when water hits hot brake parts and get between rotor and pad reducing force of contact. Venting of organic pad gases is pretty much obsolete with the new compounds of today. Notice pic of cracked slots. Hope this info helps. 
<ul><li><a href="http://www.kvrperformance.com/newpage4.htm">KVR Performance</a></li></ul>
<ul><li><a href="http://www.kvrperformance.com/newpage4.htm">KVR Performance</a></li></ul>
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01-13-2002, 10:04 AM
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The craziest car nut I know. Read his stories for a good laugh. Pulp Racing products are fun too. He went from drilled with stock pads, to slotted with different pads, etc. Read the story parts to understand why he made these choices.
http://www.nsxfiles.com/NSX_mods.htm
Ford boys with big motors.
http://www.shotimes.com/brakes/part2.html<ul><li><a href="http://www.surrealmirage.com/subaru/brakes.html">Direct response to KVR</a></li></ul>
http://www.nsxfiles.com/NSX_mods.htm
Ford boys with big motors.
http://www.shotimes.com/brakes/part2.html<ul><li><a href="http://www.surrealmirage.com/subaru/brakes.html">Direct response to KVR</a></li></ul>
01-13-2002, 10:15 AM
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Regarding the cracked rotor photo ...
.... it's interesting that the slots did not seem to initiate the cracks, but I'd say that this rotor is right on the edge of catastrophic failure.
We certainly replace the drilled rotors on our FC long before they look this bad!
We certainly replace the drilled rotors on our FC long before they look this bad!