Bronco Full Size V8-302 5.0L (1986)
Brake Rotor/Disc: Service and Repair
Servicing
Each time the brakes are serviced, the disc brake rotor should be checked for scoring, runout, parallelism and thickness.
ROTOR MACHINING
Do not machine, cut or true up new front disc brake hub and rotors prior to installation on vehicle. Making a light cut on a new front disc brake
hub and rotor may cause excessive runout and result in brake shudder several thousand miles later. It is best to clean oil film off new front disc
brake hub and rotor with Brake Cleaner or equivalent install it on vehicle.
Never use a brake lathe that cuts only one face of the front disc brake hub and rotor at a time. It must be a simultaneous straddle cut. All front disc
brake hub and rotor refinishing must adhere to the rule that equal amounts of front disc brake hub and rotor stock are removed from each braking
surface each time a front disc brake hub and rotor is refinished.
On-vehicle brake lathes, machine the front disc brake hub and rotor while it is on the hub and is turning on the same axis as the hub. This
procedure reduces front disc brake hub and rotor lateral runout to near zero by cutting the front disc brake hub and rotor perpendicular to the axis
of the hub, therefore cancelling the affect of stacked tolerance of the front disc brake hub and rotor and front wheel spindle. Follow the on-vehicle
brake lathe manufacturer's instructions on machining procedures.
A bench-mounted disc brake lathe machines the disc brake hub and rotor to the axis of the lathe arbor and will not reduce total lateral runout
associated with stacked tolerances of the front disc brake hub and rotor and front wheel spindle. Follow manufacturer's instructions on machining
procedures.
With both types of brake lathes, set cutting tool to just contact the high spots on the front disc brake hub and rotor then adjust cutting tool to the
minimum depth required to clean up the front disc brake hub and rotor face. The total material removed (combination of both sides) must not
exceed the minimum discard thickness that is marked on the inside of the front disc brake hub and rotor.
To improve initial brake pedal feel and surface finish on a machined front disc brake hub and rotor, lightly sand rotor surface with 120 grit paper
prior to road testing.
