Kawi2strokes.com Forum

Actually, there a percentage of guys that don't care about the weight or stopping power, they just want the "look". And that will decide my reply. As far as holes, there is an equation for the size, but I can't find it.

Intellectually, if one looks at factory discs, street and race, it would be an indicator of what works. Which for many years, has been thin discs with a few smaller holes, and "waves" to remove even more weight. Not a bunch of big holes swiss style, which I have never seen from a factory. That's good enough for me.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

Well, consider these disks were patterned after the 1965 Porsche Can-Am disks, and were done for no other reason than reduction of weight, as I said. We didn't have specialty disks back then, nor fancy stuff to use, we pulled street bike disks from regular parts stock, and worked/ran with what we had.

I have used some of those 1973 drilled disks for 40 years, and not had one issue with failure, nor lack of stopping power, even with lesser Z1 calipers. They work well with Brembo, Lockheed and other "butterfly" calipers.

They were the FIRST effort in disk drilling, and they weren't done for "appearance".

No-one is forcing any one else to use that pattern, and, Kawasaki did not have the rights to use that pattern, so, WE, working with Kawasaki, U.S.A. R&D engineer Hank Hosoi, came up with a different drill pattern, what most stock drilled disks used for DECADES on production bikes.

That IS the history of it all, not speculation, not theory, FACT, and, we both have heard EVERY hair brained and/or idiotic reason/theory for drilling disks, all but one, incorrect. We got the idea that our disks were too heavy after seeing factory race disks on Ron Grant's TR750 Suzuki in 1972, they were radially vented honeycomb style, and, lighter.

The noise these make is the air inside the holes heating from the friction as the pads close the holes off, then open as the holes become uncovered. The noise has NO effect on braking.

I wouldn't e scared to remove materials, and/or thin these disks, and, then run them on any of my bikes, and, I don't ride soft.

Jim, you mentioned you had disk failure(s) with this drill pattern, would you be so kind as to elaborate, I'd like to know what happened, and, why, if you would care to give the info, sir.

It was about 1979. My pattern was with 3/8" holes, and I put a bunch of them in the single disk of my H2. Next time I come across the disk, I'll count, but they were fairly close spaced. Shortly after I put it on, I had the need to stop quickly from about 45 mph, twice in a row. The second time, the disk was so hot that the brake faded badly and I almost sailed through a red light. The pads were stock.

I started thinking about it, and with the thickness of a stock rotor and 3/8" holes, I had removed very nearly the same disk surface area as I had added. That is, the area of the cylinders created by drilling the holes was about equal to the two 3/8" disks I removed. This means I had about the same cooling area, but much less rotor mass. I immediately changed to a dual stock disk and caliper setup, and when I looked at the pads that had been used on the drilled disk, they were almost to the metal backing. They were pretty much burned up.

Maybe semi-metallic pads would have cured the problem, maybe something else would have, but I wasn't going to keep experimenting after almost running a red light at a busy intersection.

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If it surges, that's normal, upshift.

H1 wanted opinions, I gave him mine.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........

The diameter of the holes can be twice the rotor thickness to keep the same surface area. Don't go any bigger than this. As far as how many is to many, I don't have an answer.



I would think you would want the hole to be right out to the edge of the pad or slightly over to get even pad wear. I am pretty sure the holes help to "clean" the pad and any area that is not in contact with one would wear at a different rate. I could be totally wrong on this though, I would have to look at some factory rotor and pad setups.

I only have one season on my disk but zero streaks on the rotor so far.

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http://kawatriple.com/wtf/

And, I gave him what we did to do the first drilling, and, my opinion as well, from practical, hands-on, I was th4ere, did that application, 40 years of it.

Jim, the only reason I can think of for the pads doing that is possibly, the champher on the holes wasn't enough, not the right angle, that stuff does make a difference. We used stock street bike pads as well, nothing special, no aftermarket pads. I can see if the holes weren't champhered enough,m the pads could get cut away, but quick. I would also think that if that occurred, the heat from the process would be intense, possibly enough to elaminate the pad material from the pad backing. NOT GOOD, sir. We ran those setups hard, at a lot of different tracks, long, short, low braking like Talladega, Ontario, to lots of intense braking, like Laguna, Loudon, and never had a problem.

The engineer that did the first pattern for us, Dave Hussey, a Bertea Corporation Engineer that moonlighted doing the reverse blueprints for Elliott Morris (Morris Mags, they were literally on the other side of the wall in the facility we were in, in So. Cal.). Dave was the one that did the investigation of the "holy disks" off the Porsche's, and found the holes should be twice the thickness of the disk. The factory disks were .240 thick, so, we fudged, and "rounded the holes off" to 1/2 inch, from the spec .480 inch diameter, and champhered with a 60 degree angle cutter, .040 deep per hole opening.

We took the swept area of the disk, inner and outer edges, and moved the outer and inner holes IN from the pad edges .100 inch. We did what Walms says, we left the edge of the pad past the hole edge runs.

That's the way we did it for the first time, a long time ago. Somebody had to start this whole "holy disks" mess, just to keep Dave Hussey happy.

This problem was a fast overheat and fade, burning up the pads. You could smell it. It worked fine until I had to do the two fast stops in a row, and then no front brake. It was a single drilled disk, not dual.

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If it surges, that's normal, upshift.

I'll be honest, I only did this for the look. shoot me John!
I noticed no difference in braking power or fading.
No chamfers, the disk was ground after drilling, I didn't even debut the holes.
This disk was also thinned to 6mm.

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http://kawatriple.com/wtf/

BANG!..... LOL, and factory disc's, (including aftermarket disc's) the holes are not chamfered.

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Twist the throttle, tilt the horizon, and have a great time. What triples are all about...........