Dust build up in cross drilled rotors
05-12-2007, 09:24 AM
#16
Drifting
Originally Posted by Yummybud924
what is the purpose of using crossdrilled rotors?
just wonderign because I read that they serve no purpose and are just put on new cars because they look cool.
just wonderign because I read that they serve no purpose and are just put on new cars because they look cool.
05-12-2007, 10:01 AM
#17
Team Owner
the "Theory" is that when you brake hard the interaction between the pad and rotor creates a gas like substance that will cause brake fade as it will be a barrier between pad and rotor ..yeah like a gas can't be compresed anyway with thousands of pounds per square inch being applied... 
The holes are to vent this gas away. Many people think it is heat dissipation but that is crap anyway ...less mass of rotor aloows heat to build up on what is actually there as the heat dissipation through venting is a secondary function vs heat dissipation through conduction under heavy braking anyway. The heat "flash" needs to be absorbed by the rotor.
May help you very very slightly at the track where repeated heavy braking is done but i have NEVER seen impirical data to prove it NOT put out by a rotor manufacturer.
For street cars it is a total style thing ... most guys who will tell you that they make a difference are the guys who just spent big money on them...
The holes are to vent this gas away. Many people think it is heat dissipation but that is crap anyway ...less mass of rotor aloows heat to build up on what is actually there as the heat dissipation through venting is a secondary function vs heat dissipation through conduction under heavy braking anyway. The heat "flash" needs to be absorbed by the rotor.
May help you very very slightly at the track where repeated heavy braking is done but i have NEVER seen impirical data to prove it NOT put out by a rotor manufacturer.
For street cars it is a total style thing ... most guys who will tell you that they make a difference are the guys who just spent big money on them...
05-12-2007, 10:57 AM
#18
Instructor
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yummybud crossdrilled rotors cool the face of the pads putting holes in the rotor is the only way to get air to the face of the pad . and no a street car does not need them after all how much brake fade do you get going to work ?
05-12-2007, 04:40 PM
#20
Instructor
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The pagids have been on for about 2 weeks now and the "rusty wagon wheel" noise on light braking has completely disappeared. Coming from the OEM pads, 87944, I rather like them. They have a bit more "bite" to them. The rims dust up very quickly though, quick wipe up every week is all.
05-12-2007, 10:15 PM
#23
Three Wheelin'
Jeff,
Porsche sells these sticky spiderweb like pads to put on the back of the pads that fit in the pistons to help keep the pads from moving back and forth in the caliper so they won't squeel....Good luck!!!!
Steve
Porsche sells these sticky spiderweb like pads to put on the back of the pads that fit in the pistons to help keep the pads from moving back and forth in the caliper so they won't squeel....Good luck!!!!
Steve
05-13-2007, 04:01 PM
#24
Intermediate
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Originally Posted by Yummybud924
what is the purpose of using crossdrilled rotors?
just wonderign because I read that they serve no purpose and are just put on new cars because they look cool.
just wonderign because I read that they serve no purpose and are just put on new cars because they look cool.
Well, they do serve a purpose in extreme applications. On a street car they are unnecessary, a simple slotted+vented rotor is more than enough even on spirited drives.
slots and Xdrilled holes are basically there to vent gasses and heat that come off the brake pads... Unless it's a factory or high end Xdrilled rotor the holes end up causing more trouble than they are worth (cracking around the hole and chewing up the brake pads faster)
but they do look cool 
05-13-2007, 08:54 PM
#25
Drifting
having just designed a set, I can tell you it does squat for cooling. In fact the holes are heat concentrators, since they lack the metal to dissipate heat as efficiently around the hole.
The purpose of cross drilling is to remove weight with a negligible change in braking performance.
The purpose of cross drilling is to remove weight with a negligible change in braking performance.
