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Thread: Portable disc brake rotor lathe - GIF

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    Jon is offline Jon has agreed the Seller's Terms of Service
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    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?

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    Supporting Member hemmjo's Avatar
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    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;

    Your dad was correct.

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    Quote Originally Posted by hemmjo View Post

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

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