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Old 06-07-2006, 05:46 PM   #11
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Most brake shops won't turn drilled rotors. So plan on possibly throwing them away in a year if they even last that long (instead of having them turned).

Reducing braking surface with holes is ridiculous. The holes do nothing for performance on a street car. Slots do.
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Old 06-07-2006, 05:52 PM   #12
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Quote:
Originally Posted by willwren
Most brake shops won't turn drilled rotors. So plan on possibly throwing them away in a year if they even last that long (instead of having them turned).

Reducing braking surface with holes is ridiculous. The holes do nothing for performance on a street car. Slots do.
uummm willwren i have road in my brothers truck and the Holes do make a big siffrence, my head almost hit the windsheld when hit slams them on. and man it stops vary fast from80 or so...

and if the less braking surface is back with the holes why to brand new rice bikes come with swiss cheese roters? they stop just fine...

my bro did ALOT of research on them befor he got them... and wow it maid a HUGE diffrence is stoping power
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Old 06-07-2006, 05:57 PM   #13
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Bandit, new rotors and pads do make a difference. If you drilled your current rotors and made no other changes, you would lose braking efficiency.

Motorcycles have holes CAST into the blanks because they can make the rotors larger in diameter to gain back the surface area they lose from the holes.
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Old 06-07-2006, 06:11 PM   #14
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Quote:
Originally Posted by willwren
Bandit, new rotors and pads do make a difference. If you drilled your current rotors and made no other changes, you would lose braking efficiency.

Motorcycles have holes CAST into the blanks because they can make the rotors larger in diameter to gain back the surface area they lose from the holes.
then how come if the less surface make brake * dont stop as good then why are my brothers brake working better now then when he used reguler roters?
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Old 06-07-2006, 06:35 PM   #15
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Different pad and rotor materials or quality. If the holes were filled, he'd have better braking.

You're not understanding all the dynamics here. Drilled rotors micro-crack with heat cycling over time. Each hole weakens the rotor. When the rotor is weakened, and it heats up, it can crack and break. This can cause caliper damage, wheel damage, tire damage, or any number of other issues. This is why most brake shops won't turn drilled rotors:

1. They don't want the liability. Lawsuits suck.
2. The already weaker rotor becomes even weaker when material is removed during turning.
3. The rotors can come apart during turning if they've already cracked.
4. Most crossdrilled rotors are used on rice for show, no go (or stop) and are typically abused.
5. Most brake shops know the applications and proper brake component selections.

Premium 'crossdrilled' rotors aren't actually drilled. The holes are cast into the blanks first, then hardened, then turned to the final thickness before being sold. This procedure is used on PREMIUM performance rotors. Perhaps 5% of the drilled rotors on the market. They are also typically part of a 'big brake' kit, or are replacement rotors for cars that had these rotors OEM from the factory, and the larger diameter was pre-designed into them.

95% of the 'drilled' rotors on the market today are for show. And they are inferior because of it.
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Old 06-07-2006, 06:42 PM   #16
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Quote:
Originally Posted by willwren
Different pad and rotor materials or quality. If the holes were filled, he'd have better braking.

You're not understanding all the dynamics here. Drilled rotors micro-crack with heat cycling over time. Each hole weakens the rotor. When the rotor is weakened, and it heats up, it can crack and break. This can cause caliper damage, wheel damage, tire damage, or any number of other issues. This is why most brake shops won't turn drilled rotors:

1. They don't want the liability. Lawsuits suck.
2. The already weaker rotor becomes even weaker when material is removed during turning.
3. The rotors can come apart during turning if they've already cracked.
4. Most crossdrilled rotors are used on rice for show, no go (or stop) and are typically abused.
5. Most brake shops know the applications and proper brake component selections.

Premium 'crossdrilled' rotors aren't actually drilled. The holes are cast into the blanks first, then hardened, then turned to the final thickness before being sold. This procedure is used on PREMIUM performance rotors. Perhaps 5% of the drilled rotors on the market. They are also typically part of a 'big brake' kit, or are replacement rotors for cars that had these rotors OEM from the factory, and the larger diameter was pre-designed into them.

95% of the 'drilled' rotors on the market today are for show. And they are inferior because of it.
unfortunately bill, your first comments give the impression that no matter what, anything that are typically called cross-drilled rotors are all junk and will do more harm than good on a street application...

whereas in real life, SOME drilled rotors are simply drilled OEM spec rotors and SOME are actually a better quality cast rotor...
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Old 06-07-2006, 06:54 PM   #17
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Most are junk and not appropriate for street use.

Some (limited few) are OEM applications and good-quality, but the diameter should be increased when going to those. Most of us can't afford these limited few good ones.

One more thing during turning: The cutting tool can chip away the entrance to the hole during turning as the tool catches the brittle edge. This isn't a problem on quality slotted rotors, as they predetermine the slot valley angle to account for turning. Quality drilled (cast hole) rotors have a generous chamfer on the entrance and exit of the hole for this reason.
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