Drilled stock rotors?

Samelak
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Drilled stock rotors?

Post by Samelak »

I have been thinking about drilling my stock rotors but I am unsure if its worth the effort.I am a machinist by trade and have access to a CNC mill that woud make the task simple. Any opinions from the forums would be appreciated.

Thanks, Lee

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zxbob
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Re: Drilled stock rotors?

Post by zxbob »

Drilled disks are a ++ (IMHO)

Bob
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NobleHops
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Re: Drilled stock rotors?

Post by NobleHops »

Samelak wrote:I have been thinking about drilling my stock rotors but I am unsure if its worth the effort.I am a machinist by trade and have access to a CNC mill that woud make the task simple. Any opinions from the forums would be appreciated.

Thanks, Lee
IIRC you are restoring an 80, yes? Would you do a few others while you're setup?

N.
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Re: Drilled stock rotors?

Post by EMS »

Drilling rotors is a pain in the neck. I had several sets done in our shop and the number of bits the guy went through did hardly make it worth it. Make sure you have a decent pattern to use as a template. Ideally you would use a rotor that is already drilled and set it up as a guide.

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spencer
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Re: Drilled stock rotors?

Post by spencer »

I've always wondered, and maybe you guys can tell me; what is the reason to drill brake rotors? Do they cool better? I doubt it. Is it because they look cool? The only real effect I can see is that there is slightly less friction area, which would make them not work as well as solid rotors. I'm not throwing cold water on the idea. I really do wonder why people drill them.
SCH Rochester, MN

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NobleHops
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Re: Drilled stock rotors?

Post by NobleHops »

spencer wrote:I've always wondered, and maybe you guys can tell me; what is the reason to drill brake rotors? Do they cool better? I doubt it. Is it because they look cool? The only real effect I can see is that there is slightly less friction area, which would make them not work as well as solid rotors. I'm not throwing cold water on the idea. I really do wonder why people drill them.
I understood the benefits to be threefold: better cooling, better bite when wet, and less rotational mass/unsprung weight. Oh and they look cool :-).

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zxbob
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Re: Drilled stock rotors?

Post by zxbob »

NilsMenten wrote: I understood the benefits to be threefold: better cooling, better bite when wet, and less rotational mass/unsprung weight. Oh and they look cool :-).

N.
Thats 4 :wink:

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Re: Drilled stock rotors?

Post by NobleHops »

:-)

Got me there. Off to the garage to shine up the bike and then possibly to a vintage meet! Will post pics if I do

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Re: Drilled stock rotors?

Post by EMS »

Performance in the wet is definitely the major reason for cross-drilling rotors.

4139

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spencer
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Re: Drilled stock rotors?

Post by spencer »

Well, I guess I don't need to worry about drilling mine then. Since I have owned my CBX, other than washing it, it has only been slightly damp once. I have never had to ride it in a rain. :dance:
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SteveG
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Re: Drilled stock rotors?

Post by SteveG »

Well, I guess I don't need to worry about drilling mine then. Since I have owned my CBX, other than washing it, it has only been slightly damp once. I have never had to ride it in a rain.
It seems like every time I head out for a good ride I get rained on. And that is half the fun, the unknown. But what matters is riding the CBX. Rain, shine, who cares.

Steve

PS - The brakes work more than well enough in the rain without being drilled.

On my way to the Luray, Virginia fall ride in '08:

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In Rhinebeck, New York at the Antique Bike Show / Meet in'10:

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82 CBX, 82 CB900F Project, 81 CB900(985)F, 79 CB750(810)F, 06 Wee-Strom

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Re: Drilled stock rotors?

Post by alimey4u2 »

I drilled my originals on my 80, worked out fine. Sold them on e-bay when I upgraded to PM & the fellow was delighted...
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59Cushman
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Re: Drilled stock rotors?

Post by 59Cushman »

Just attended a driving event held by Cadillac, with instructors from the Skip Barber school. The subject of drilled rotors came up, and the experts asked if anybody had ever seen a drilled rotor on a true racing car. Nobody had. While drilling does remove some weight, it weakens the material and leaks to stress fractures. They had plenty of photographs to back this up. I don't need to worry about a disc failure due to wanting a higher "cool" quotient.

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Re: Drilled stock rotors?

Post by ericfreeman »

Here's a photo of the brake disc on a Porsche 917-30, arguably one of the fastest road racing cars ever built. Sure looks like holes in that disc to me.....Guess those Skip Barber fellows need to get out more often.

Eric

Image

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spencer
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Re: Drilled stock rotors?

Post by spencer »

917-30? That would be Mark Donahue's number 6 or 7. (Actually, I guess about 5 exist, but only two were actually raced.) Absolutely my favorite race car of all time. Do you have any more pictures of it? I only have a few from when I saw Mark race it at Road America, in 1973.
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