Rotor Description and Repair

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Rotor Description and Repair
Rotor Inspection & Repair
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Rotors play an important part of any modern vehicle. Proper inspection and repair will result in increased safety while driving and reduce costly and unnecessary repairs to your brake system.

MACHINING ROTORS

It is not always necessary to refinish brake rotors when doing routine brake maintenance such as replacing brake shoe and lining assemblies. Refinish rotors only under the following circumstances:

1. There is brake pedal pulsation.

2. There are heat spots, cracks, or excessive scoring.

Brake rotors have a minimum thickness cast into them. This dimension is called a discard thickness and not a refinish dimension. Do not use a brake rotor that is below the discard thickness after refinishing. Replace it with a new one because a rotor below minimum thickness it will not have the proper heart transfer capabilities. Control of rotor tolerances is necessary for the proper performance of disc brakes.

Always use precision brake lathe for machining rotors. Locate the deepest score and turn the rotor micrometer knobs until the tool bit bottoms out at the deepest point of the score. Zero the scale and back out the tool bits. Advance the cutter hand-wheel until the bits have cleared the inner edge of the rotor face. Adjust the micrometer knobs for approximately .005 " (.0127 mm) more than the first reading. This will ensure clearing the rotor in one cut. It is important that you make the rotor surface non-directional by dressing the rotor surfaces with a sanding block with 150 grit aluminum oxide sandpaper. With the rotor turning approximately 150 RPM, sand each rotor surface using moderate pressure for a minimum of 60 seconds. After sanding the rotor clean with brake rotor with soap and water.

The finished rotor surface should be as close to that of a new rotor as possible.

 

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