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Old 06-08-2007, 07:28 PM   #1
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slotted vs cross drilled rotors

slotted vs cross drilled rotors. Which would be better for street and some track/autocross? Also can either be resufaced like regular flat rotors?

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Old 06-08-2007, 07:33 PM   #2
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For the past 2 years i have used the cross drilled. From my understanding either will work on the track very well, the cross drilled would work better in wet conditions.
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Old 06-09-2007, 02:23 PM   #3
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The drawback to cross drilled is there tendancy to develop hairline cracks. Rule of thumb is once the cracks link one hole to another, the rotor is done. Slotted rotors don't behave this way and would likely be a better choice for your needs.

People don't re-surface rotors much anymore.

Also consider that a change of brake pad compound and brake fluid bleeding can have a greater impact on braking than simply changing the rotor.
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Old 06-09-2007, 04:28 PM   #4
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Quote:
Originally Posted by racer_d
The drawback to cross drilled is there tendancy to develop hairline cracks. Rule of thumb is once the cracks link one hole to another, the rotor is done. Slotted rotors don't behave this way and would likely be a better choice for your needs.

People don't re-surface rotors much anymore.

Also consider that a change of brake pad compound and brake fluid bleeding can have a greater impact on braking than simply changing the rotor.
agreed. there's very little differenc in performance between flat, slotted or drilled rotors. there is, however, a HUGE difference in performance between pad compounds. if you REALLY want to stop well, realize that the weak link in your braking system is usually your tires, so upgrade those.

if you go to the track a lot, consider getting your rotors cryo treated. it's about $30 per rotor and will keep them from warping. they will also last much longer.
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Old 06-10-2007, 12:27 PM   #5
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I don't really know much about this, but for heavy use on the track isn't there an advantage to the drilled b/c of airflow and cooling.
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Old 06-10-2007, 01:10 PM   #6
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I don't really know much about this, but for heavy use on the track isn't there an advantage to the drilled b/c of airflow and cooling.
supposedly. i don't think that the airflow issue matters much as essentially all high performance rotors are vented anyway; this provides the primary means of convection cooling. i DO think that drilled or slotted rotors help w/ green fade or with transfer buildup by giving escaped gasses, brake dust, etc a place to go rather than between the rotor and pad.

i don't think you can install a drilled rotor on a car and really tell the difference between a solid one. if it makes a difference, it's secondary, and it carries an added risk of cracks and an added disadvantage of reducing swept area. i DO know that plenty of race teams opt for solid rotors.
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Old 06-12-2007, 11:56 AM   #7
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Why not get the best of both worlds? They do make cross-drilled and slotted together in one rotor you know. The slotts are placed in between the drilled spots. That's what I'm getting.

Last edited by porsche986spyder; 06-12-2007 at 12:03 PM.
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Old 06-12-2007, 03:25 PM   #8
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I have slotted and cross drilled rotors now. As mentioned there does not seem to be much of a difference vs solid rotors. EXCEPT that after my 1st DE the pads glazed over. My brakes squealed for a week. I was told that this was because the gas produced by the heat and heavy use on the track formed a glaze on the pad. I was also told that either slotted or drilled rotors would solve this problem and it did. I sure hate it when my Boxster's brakes squeal so much people think a bus is pulling up alongside them. I was also told that slotted rotors would wear your pads faster though as they will be creating a slight slicing action as the pad goes across the slot. Also at high speed there is a humming sound when you hit the brakes. I kind of like it.

I don't want to open the whole stopping power can of worms but you should really put some Pagid orange's on for a track day. I swear they have a tremendous amount of stopping power.
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Old 06-12-2007, 03:35 PM   #9
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I don't know anything about this subject, but I can offer the following:

1) Cross drilled rotors look cool!
2) Cross drilled rotors dump dirty water all over your clean wheel barrels after washing the car, when you first move it.
3) Drying your car with a leaf-blower greatly reduces the negaitive effects of #2 by >90%

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