DIY Disc Brake Resurfacing with the Flex-Hone® for Rotors

Do your disc brakes squeak or squeal? As DSPORT magazine explains in a new article, and as Brush Research Manufacturing (BRM) shows in a new YouTube video, you may want to look at your brake rotors. Brake pad glaze and surface corrosion are common causes of noisy disc brakes. Fortunately, there’s a surface finishing solution that’s as easy-to-use as a power drill. Trusted by professional and DIY brake mechanics alike, the Flex-Hone for Rotors® is ideal for new and turned rotors.

Rotor Refurbishment 

In Glaze is for Donuts: Do-It-Yourself Disc Brake Resurfacing, Jun Chen of DSPORT magazine explains why BRM’s Flex-Hone® for Rotors is the right tool for rotor refurbishment. For years, Flex-Hone® users such as machine shops, manufacturers, and engine builders have been using flexible hones to improve the surface finish of cylinder walls. The Flex-Hone® for Rotors is designed for flat surfaces instead, but uses BRM’s Flex-Hone® technology to impart a superior, non-directional surface finish.

As the “Quick Tech” article in DSPORT’s August edition explains, some motorists blame vibrations while braking on warped rotors. Most modern rotors are made of iron, however, and are unlikely to warp because of this metal’s hardness and stability. Typically then, brake vibration is caused an uneven layer of material that’s transferred from the brake pad to the brake rotor. Improper pad bedding isn’t the only cause of brake problems, however, as surface corrosion and improper machining may be to blame.

Brush Tool Selection and Use

Suitable for use with a handheld electric drill, the Flex-Hone® for Rotors comes in coarse, medium, and fine grits. Coarse-grit brush tools remove heavy buildup and corrosion. They also remove sharp edges on rotor slots and cross-drilled holes that can contribute to rotor cracking. Medium-grit Flex-Hone® for Rotors tools also remove layers of pad material, but impart a smoother surface. Fine-grit flexible rotor hones impart the finest finish of all, and may be used after coarse-grit and then medium-grit tools.  

To test the Flex-Hone® for Rotors under real-world conditions, DSPORT magazine acquired four brake rotors from a race car with some time at the track. Equipped with cordless drill and a coarse-grit brush tool, the crew removed the transfer layer from each rotor’s face. The DIY mechanics then switched to a medium-grit tool, and finally to a fine-grit tool. Because the Flex-Hone® for Rotors is self-leveling and applies uniform pressure, keeping the brush tool square and flat was an easy task.

Best Practices for Resurfacing Brake Rotors

“Be sure to have at least a 50-percent overlap between passes to ensure that no rough our untouched edges remain,” author Jun Chen advised DSPORT readers. As BRM explains in its Flex-Hone for Rotors® brochure, users should work in towards the center and then out to the edge, applying light pressure to the rotor’s face. Rotate the tool between 300 and 600 RPM, and remember that dwell time – not excessive pressure – produces the desired finish.

BRM also advises Flex-Hone® for Rotors users to hold the rotor in a brake lathe, and to spin the rotor between 125 and 210 RPM during honing. DSPORT magazine recognized that some DIY brake mechanics don’t have a lathe, however, so its crew placed the brake rotors on a workbench. “This process will leave a finish very similar to a new rotor”, the author explained before concluding that “the Flex-Hone for Rotors can help you save a few bucks and get rid of that annoying brake judder for good.