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Drilled and Slotted Rotors

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Old 09-14-2004, 03:23 PM   #1
ddonzella
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Default Drilled and Slotted Rotors

Was looking at purchasing drilled and slotted rotors for my 86. One guy reccommended I purchase a dimple and slotted rotor instead. Said there better for the street and more durable, very simular look.

Would appreciate any opinions or experiance on these.
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Old 09-14-2004, 03:58 PM   #2
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Your guy is right.

Cheaply done "drilled" rotors will crack at the holes. Properly done "drilled" rotors are rather expensive, mainly, cause the holes are CAST into the rotor, not just drilled.

Dimples and slots will work just fine for the street (releasing gas buildup between the pad and rotor) without fracture. Plus, they will add the visual excitment you are looking for.
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Old 09-14-2004, 05:02 PM   #3
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Thank you! The drilled ones are cheap in cost. Made in Brazil. Any other views out there?
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Old 09-14-2004, 06:28 PM   #4
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Run, do not walk, away from cheapie drilled rotors. Hard braking will cause them to crack around the holes at first and may fail at a point when you really want good braking.

Slotted rotors will look nice and they do work. Just be careful when getting the slotted rotors as some need a specific pad composition for them to work properly. Look here for some good information on drilled/dimpled/slotted rotors: http://www.tirerack.com/brakes/index.jsp

Early C4 brakes are smaller in diameter than the later C4's and you might want to consider upgrading to the later 13" J55 rotors or even a C5 brake system. Really good performance pads are hard to find for both front and rear brakes on the 84-87 cars. You can get Hawk or Performance Friction for the front but there is not much for the rears. EBC has some good pads for street,vautocross and the occasional track day use (Greenstuff) and the Redstuff pads work for more serious autocross and track days but not for street use.
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Old 09-14-2004, 09:59 PM   #5
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Hell, even the cross drilled rotors that are done right aren't necessary - decrease the surface of the rotor = increase braking distance. Slotted rotors are all anyone needs for the street or even (most) track use.
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Old 09-14-2004, 10:53 PM   #6
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Quote:
Originally Posted by c4cruiser
...
Early C4 brakes are smaller in diameter than the later C4's and you might want to consider upgrading to the later 13" J55 rotors or even a C5 brake system.
...
Be sure and keep in mind that these brake upgrade require you to replace your wheels. The 13 inch'ers will not fit behind the stock 16 inch rims. And finding the right size for an 84-87 vette is a serious pain..... unless you want the same 5 spoke ZR-1 rim that EVERYBODY else uses.
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Old 09-15-2004, 01:55 AM   #7
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I liked my dimpled ones which were made by GT Rotor. Sadly, I have not been able to find them anymore. Anyone know of a source?
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Old 09-15-2004, 01:14 PM   #8
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You really don't even need slotted rotors these days. Pad materials don't out-gas like they used to. Your best bet is a well made solid rotor, most people are moving back to solid rotors for track applications (street cars, anyway).

However, if you're looking for the "racing" look but aren't actually tracking the car, get slotted over drilled for the reasons mentioned above. You're not really gaining any performance (in fact you're decreasing pad and rotor life), but you're not losing any, either.

Last edited by ScaryFast; 09-15-2004 at 01:19 PM.
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Old 09-15-2004, 02:48 PM   #9
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Quote:
Originally Posted by aeronautica86
Hell, even the cross drilled rotors that are done right aren't necessary - decrease the surface of the rotor = increase braking distance. Slotted rotors are all anyone needs for the street or even (most) track use.
say what? Do you really think that by "drilling" rotors, they are going to lose enough surface area to actually INCREASE braking distance?

If that was the case, why to all forms of pro racing use drilled rotors?

It's because it helps braking... the drilling releases gas built up during hard breaking. That pressure will actually push a pad away from the rotor.

It also acts, to a degree, like a cheese grater, which lowers the chances of the pad glazing.

Finally, the holes help dispell heat, too, by providing better cooling.
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Old 09-15-2004, 09:11 PM   #10
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Quote:
Originally Posted by aklim
I liked my dimpled ones which were made by GT Rotor. Sadly, I have not been able to find them anymore. Anyone know of a source?
I think they went out of business, they used to be right around the corner from me.
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Old 09-16-2004, 02:28 PM   #11
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Quote:
Originally Posted by bogus
say what? Do you really think that by "drilling" rotors, they are going to lose enough surface area to actually INCREASE braking distance?

If that was the case, why to all forms of pro racing use drilled rotors?

It's because it helps braking... the drilling releases gas built up during hard breaking. That pressure will actually push a pad away from the rotor.

It also acts, to a degree, like a cheese grater, which lowers the chances of the pad glazing.

Finally, the holes help dispell heat, too, by providing better cooling.
For the past 15 or so years pads with little to no outgassing have been available; want to stop faster, go with a good pad and a solid rotor. Those same pads won't glaze, so no need for any "cheesegrating" action Reduced surface area really does = less friction, so with no outgassing, the point is moot. As per cooling, get directionally vented rotors (as opposed to radially) - will cool much better then simply cross drilled.

The pad compounds have come a long way, but a lot of people still believe it's all in the rotor :-/
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Old 09-17-2004, 12:06 AM   #12
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Actually, "drilled" rotors have more surface area and that would mean more area to dissapate heat. On the other hand, they have less pad contact area. Also, as stated before, there are set ups with good NON drilled rotors and pads that are better than drilled. Now days its more for looks, old days they were the way to go.
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