Front Brake Disc Inspection

Runout


1.Raise the front of the vehicle, and make sure it is securely supported. Remove the front wheels.

2.Remove the brake pads.

3.Inspect the disc surface for damage and cracks. Clean the disc thoroughly, and remove all rust.

4.Install suitable flat washers (A) and wheel nuts, and tighten the nuts to the specified torque to hold the brake disc securely against the hub.

 

5.Set up the dial gauge against the brake disc as shown, and measure the runout at 10 mm (0.4 in.) from the outer edge of the disc.

Brake disc runout: 
 Service limit: 0.10 mm (0.004 in.) 

6.If the disc is beyond the service limit, refinish the brake disc.

Max. refinish limit: 21.0 mm (0.83 in.) 

NOTE:

Thickness and Parallelism


1.Raise the front of the vehicle, and make sure it is securely supported. Remove the front wheels.

2.Remove the brake pads.

3.Using a micrometer, measure disc thickness at eight points, approximately 45° apart and 10 mm (0.4 in.) in from the outer edge of the disc.

Brake disc thickness: 
 Standard: 24.9-25.1 mm (0.98-0.99 in.) 
 Max. refinishing limit: 23.0 mm (0.91 in.) 

Brake disc parallelism: 0.015 mm (0.0006 in.) max. 

NOTE: This is the maximum allowable difference between the thickness measurements.

 

4.If the smallest measurement is less than the max. refinishing limit, replace the brake disc.

5.If the disc is beyond the service limit for parallelism, refinish the brake disc with an on-car brake lathe.
The Kwik-Lathe produced by Kwik-way Manufacturing Co. and the ‘‘Front Brake Disc Lathe'' offered by Snap-on Tools Co. are approved for this operation.