The Flex-Hone® for Motorcycle Brake Rotors

Motorcycle brakes vibrate if the brake rotors are warped or there’s an excessive build-up of brake pad material on the face of the rotor. During bed-in, bikers can expect the transfer of some material from brake pads to rotor faces. If the bedding-in process leaves a thin, uniform layer of brake material, the motorcycle will provide smooth, cleaning braking. If the build-up is excessive or has high spots, the motorbike will vibrate because the disc pads don’t match the geometry of the brake rotors.

Brake Problems: Brake Rotors or Brake Pads?
When troubleshooting brake problems, mechanics may swap-out or true their motorcycle brake rotors and still experience front-end vibrations. Such was the case with Southbound Pachyderm of Speedzilla Message Boards, an on-line forum for street and track, supermoto, and dirt and off-road bikers. While rebuilding his Honda VFR800 Interceptor, Southbound installed the front-end from a smooth-braking Honda RC51. Unexpectedly, the rebuilt Interceptor then experienced front-end vibrations.

The Flex-Hone® for Motorcycle Maintenance
Southbound installed both new and used brake rotors and even checked the calipers and forks. When his brake problems continued, he received some sound advice from Trace, another Speedzilla member whose Honda motorcycle once suffered “the grabby shakes on perfectly true rotors”. Trace’s solution started with a phone call to Brush Research Manufacturing (BRM), where the Honda owner received some “expert advice” about using the Flex-Hone® tool for “cleaning up a rotor”.

Choosing the Right Abrasive Grit for Flexible Honing
As Southbound learned, the Flex-Hone® is available in a variety of abrasive grits for brake rotors. “The 60 and 125 grits are for heavily grooved or damaged cast iron rotors on cars,” Trace explained, “not for sportbike rotors.” For a bike like the Honda RC51, however, “the 240 grit is ideal for cleaning up a brake rotor, removing pad material, and giving it a nice surface”.  The goal, added a third Speedzilla member, is to remove what is “unscientifically” known as “brake pad gunk buildup”.   

The Flex-Hone® for Rotors with an Electric Drill
“Put the rotors on a brake lathe and set the RPM to about 150”, Trace then instructed. By chucking the Flex-Hone® for rotors into a 500-RPM drill, Southbound could “work from outside to inside for about 15 seconds”. After allowing the flexible hone and brake rotor to cool, the biker was advised to “hit it again for a final clean-up for 10-15 seconds”, but without “overdoing it”. The final step involved cleaning the “crud” out of the cooling holes and wiping the surfaces with brake cleaner.