Drilled Rotor Hole Size?

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Drilled Rotor Hole Size?

Post by BOOT » Sat Mar 09, 2019 11:54 am

I'm gonna install some drilled rotors on a car this spring and it occurred to me I could prob enlarge the holes a bit(I know small difference). Then I rem, that I also have another brand of drilled/slotted rotor and when I got them out saw they have larger drilled holes than these. I also have a 3rd brake set by another brand for another project but I don't feel like digging them out atm. So now I'm wondering what is the safest hole size?

I also noticed roughly(didn't feel like grabbing a caliper) that both chamfers were about the same OD size and of course the larger inner holes had less chamfer ID.
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Re: Drilled Rotor Hole Size?

Post by FC-Pilot » Sun Mar 10, 2019 5:12 pm

What is the application? I would say leave them. One of the beauties of slotted or drilled rotors is the lack of pad glazing we see in testing. Then again we also see about a 30% increase in pad wear. You also have the added noise you get with them. If you know what it is and anticipate it you can learn to deal with it. OEM’s that have them spend a considerable amount of time playing with different hole spacing to get the least amount of noise knowing that customers will bring their stuff in for the slightest thing

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Re: Drilled Rotor Hole Size?

Post by BOOT » Mon Mar 11, 2019 9:38 am

Noise is not a concern.

Even if I enlarged the holes past chamfer and had to rechamfer with a bit of breaking loss, is also not a concern.
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Re: Drilled Rotor Hole Size?

Post by jed » Wed Mar 13, 2019 9:51 pm

What is the purpose of larger holes?
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Re: Drilled Rotor Hole Size?

Post by Dan Timberlake » Sun Mar 17, 2019 8:19 am

In one of the late great Carroll Smith books I think he talks about detailing drilled rollers to delay cracking which can be inevitable in an application that really uses the brakes, like road racing. I think it may have been using a hardened steel ball from a ball bearing assembly and a hammer to peen each hole's chamfer at the friction surface. I think seem to recall drilled rotors were generically more problematic than slotted rotors in regards cracking.

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Re: Drilled Rotor Hole Size?

Post by BOOT » Tue Mar 19, 2019 12:25 am

weight


Interesting info, not gonna use em too hard or see a ton of use just gonna drill em a bit more like my others at least before I slap em on.
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Re: Drilled Rotor Hole Size?

Post by FC-Pilot » Tue Mar 19, 2019 2:34 pm

Admittedly I don't understand the desire to drill the holes out bigger as the weight reduction will be minimal and any performance improvement minimal at best. If you want to drill them larger and don't plan on running them hard go ahead.

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