Portable disc brake rotor lathe - GIF

Portable disc brake rotor lathe.

<video controls autoplay loop>
<source src="https://diqn32j8nouaz.cloudfront.net/portable_brake_rotor_lathe.mp4" type="video/mp4">
Your browser does not support the video tag.
</video>


Previously:

https://www.homemadetools.net/forum/...572#post147444
https://www.homemadetools.net/forum/...820#post175196
https://www.homemadetools.net/forum/...787#post175044
https://www.homemadetools.net/forum/...742#post155906
https://www.homemadetools.net/forum/...143#post176460
https://www.homemadetools.net/forum/...7059#post84946
https://www.homemadetools.net/forum/...790#post136946
https://www.homemadetools.net/forum/...415#post135435

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?

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.

Quote:

---

Originally Posted by hemmjo

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.