Checking for lateral run-out and variation in thickness, front wheels
Checking for lateral run-out and variation in thickness, front wheels |
1. |
Raise the car and remove the front wheels.
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2. |
Start by control measuring on one side.
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3. |
Press in the piston
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Levels 1, 2 and 4:
Prise against the brake pad with a screwdriver.
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Level 3:
Prise between the brake disc and the brake caliper using a screwdriver.
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4. |
Remove the brake caliper retaining bolts and lift of the caliper.
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5. |
Suspend the caliper with cable ties.
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6. |
Fit the five wheel bolts with one washer, part no. 80 73 124, on each.
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7. |
Fit
89 96 639 Gauge, brake disc
to the upper mounting lug for the brake caliper with an M10 bolt and nut. Fit a
78 40 622 Dial gauge
on either side.
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8. |
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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9. |
Rotate the disc and read the gauges. Note the runout (A) and variation in thickness (B).
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10. |
Check that the readings are within specified intervals, see Brakes - Footbrake system - Technical data - Brake discs.
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11. |
Remove the dial gauges, brake disc measuring tool and wheel studs with washers.
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12. |
If runout and thickness variation exceeds specified tolerances, the discs must be machined or replaced. see
Brake disc, front
.
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13. |
Fit the brake caliper. Secure the bolts with
74 96 268 Thread locking adhesive
.
Tightening torque: 210 Nm +30° (155 lbf ft +30°) |
14. |
Fit the wheel
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15. |
Repeat this method of measurement on the other brake disc.
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16. |
Lower the car and depress the brake pedal to press out the brake pads.
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