Portable disc brake rotor lathe - GIF

[Jon]

Portable disc brake rotor lathe.




Previously:

Rail-mounted lathe - photo
Drawknife from disc brake rotor - video
Lathe fixed steady from disc brake rotor - video
Indexing plate from brake disc rotor - video
Glowing brakes - GIF
Exploding disc brake GIF
Formula One front brake assembly - photo
DC-10 wheel and brake cutaway - photo

[bob47907]

So, what’s the conventional wisdom regarding turning disc brake rotors to relieve warpage? My dad suggested, decades ago, that turning would remove mass and weaken the structure.

Are contemporary approaches better in that respect?

[hemmjo]

If your rotors are warped, you have to either turn them, or replace them. If you turn them it trues the surface. The turning of a warped rotor actually make it more likely to warp again. As you mentioned will be thinner than before, which leads to more heat build up. BUT, it will also be of less consistant thickness since you had to cut more off of some spots, and less off of other spots in order to make surface flat.

There are many things that cause rotors to warp. Before you do anything, read this;

https://www.crossdrilledrotors.ca/bl...-rotor-warping

Your dad was correct.

[NeiljohnUK]

There are many things that cause rotors to warp. Before you do anything, read this;

https://www.crossdrilledrotors.ca/bl...-rotor-warping

Interesting, though not entirely accurate, cross-drilling and slotting may assist with cooling, but the main reason for doing such things is to vent the gases evolving from the brake friction material resins that actually grip (brake) the rotor, trapped gases are major cause of fade, slotted pads help too. My father was the Ferodo tech who developed the first slotted pads for a Jag D type racer in Southampton, using two hacksaw blades side-by-side in a standard hacksaw frame, initially for multiple leading edges to clear water as wet discs didn't work as well as drums, then in dry races the racer reported less fade with the 'wet' slotted pads. Having been better braked than the factory D types Ferodo sent an engineer to question what they were doing, soon after slotting pads became a manufacturing process.