Control measuring axial runout and thickness variation
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Control measuring axial runout and thickness variation
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1.
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Raise the car and remove the front wheels.
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2.
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Start by control measuring on one side. Press the brake piston back using a pair of slip-joint pliers.
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3.
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Remove the brake caliper and suspend it from the MacPherson strut with a cable tie.
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4.
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Fit the five wheel bolts with four washers on each bolt.
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5.
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Fit brake disc measuring tool on the lower attaching lug for the brake caliper. Fit the dial indicators. See
78 40 622 Dial indicator
.
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6.
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Rotate the brake disc while observing the outboard dial gauge. Zero both gauges when the negative reading obtained on the outboard one is at maximum.
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7.
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Rotate the disc and read the gauges. Note the runout (A) and variation in thickness (B).
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8.
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Remove the dial gauges, brake disc measuring tool and wheel bolts with washers.
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9.
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Fit the brake caliper, apply Loctite 242 part number 74 96 268 to the bolts and tighten with torque wrench.
Tightening torque 110 Nm (81 lbf ft)
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10.
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Fit the wheels. See
Wheels
.
Tightening torque 110 Nm (81 lbf ft)
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11.
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Repeat this method of measurement on the other front wheel.
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12.
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When the measurements have been completed, lower the car and depress the brake pedal to press out the brake pads.
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