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BRAKES
5-35
Fig. 5-54 Seating Boot
(a) The brake hose must be connected to the brake line
at the frame bracket.
Use extreme care to orient the hose so that the keyed
hose end fitting aligns with the slot in the bracket without
twisting or kinking the hose.
(b) After overhaul
--
or any time that the brake hose or
line is disconnected
--
the calipers must be bled.
ROTOR SERVICING
Checking Lateral Runout
1. Lateral runout is the movement of the rotor from side-
to side as it rotates on the steering knuckle spindle. This could
be described as "rotor wobble."
2. The movement of the rotor from side to side in the
lateral plane causes the brake shoe and lining and pistons to
be knocked back into their bores. This results in additional
pedal travel required and a vibration during the braking
action.
3. To check lateral runout, first tighten the wheel
bearings until all of the play is out of the bearings. Fasten a
dial indicator to some portion of the suspension so that the
point of the stylus contacts the rotor face approximately one
inch from the rotor edge. See Fig. 5-55. Set the dial at zero.
Move the rotor one complete rotation, checking the indicator
as the rotor moves.
4. Lateral runout should not be over
.004 total indicator
reading.
Parallelism Check
1. Parallelism is the measurement of the thickness of the
rotor at four or more points around the circumference of the
rotor. All measurements must be made at the same distance
in from the edge of the rotor.
2. A-rotor that varies over .0005 causes pedal vibration,
as well as front end vibration during brake applications. A
rotor that does not meet these specifications may be
Fig. 5-55 Checking Rotor For Lateral Runout
refinished to specifications if precision equipment is available.
Rotor Tolerance and Surface Finish
In manufacturing the brake rotor, tolerances of the
rubbing surfaces for flatness, for parallelism and for lateral
runout are held very close. The maintenance of these close
controls on the shape of the rubbing surfaces is necessary to
prevent brake roughness.
In addition to these tolerance the surface finish must be
held to specific range. The control of the rubbing surface
finish is necessary to avoid pulls and erratic performance and
to extended lining life.
Light scoring of the rotor surfaces not exceeding .015 in
depth, which may result from normal use, is not detrimental
to brake operation.
Machining
Since accurate control of the rotor tolerances is
necessary for proper performance of the disc brakes,
machining of the rotor should be done only with precision
equipment.
WARNING: ALL BRAKE ROTORS HAVE
A M I N I M U M THICKNESS DIMENSION
CAST INTO THEM. THE DIMENSION IS
THE M I N I M U M WEAR DIMENSION AND
NOT A REFINISH DIMENSION. DO NOT
USE A BRAKE ROTOR THAT WILL NOT
MEET
THE
SPECIFICATIONS,
AS
SHOWN BELOW, AFTER REFINISHING.
REPLACE WITH NEW BRAKE ROTOR.
ROTOR THICKNESS
H Series
Maximum
....................................................................
.880
Refinish
....................................................................
.820
Discard
..................................................................
. 8 15
Except H Series
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