Have a yen to cross-drill your motorcycle discs? Whether you have a Honda, Yamaha, Suzuki, Kawasaki, Triumph or anything else we are trying to gather successful drilling templates here. So far all of these have been provided by Murray Feldman of Murray’s Carbs – Thanks Murray!
Most of these will be able to be adjusted to your rotors by dropping the image into Photoshop over an image of your rotor (or using the dimensions of the image to match your rotor’s dimensions) and adjusting the size to suit.
- Non-model-specific – Normal and Reversed
- Non-model-specific – more holes per spiral arm – Normal and Reversed
- Honda CB400 Fast Spiral
- Honda CB550
- Yamaha XS850 3-2-3 Pattern
- Yamaha XS850 Spiral
For those interested in the engineering side of things the formula is like this:
- t: Disc thickness
- d: Hole diameter
- If d<2t the surface area will increase
- If d=2t the surface area will stay the same
- If d>2t the surface area will decrease
- The change in weight will be 3.1415 <number of holes>² t / 4 * <material density>.
Update 2019: Reader Sigurd sent in the following:
It seems your formula for calculating the weight saving is missing the hole diameter, and the number of holes should not be squared. The correct formula should be: 3.1415 * (d^2)/4 * t * * .
Try not to reduce the surface area of your brake rotor! The main job of the holes is to prevent a gas barrier/layer in wet conditions which reduces braking power, sometimes substantially. What you want to avoid, though, is lessening the surface area of the rotor so that it cannot dissipate heat as well as it should. You should be aiming to increase the area through your drilling.
Got some of your own? Let us know via the Contact Form and we will add them.