Checking brake disc lateral runout

1. Measuring requirements: No tilt play present at wheel. If required, adjust wheel bearing clearance of front wheels.

2. Fit adapter plate (Special Tool 9510/1) to wheel hub. Tightening torque of wheel nuts (mounting nuts): 130 Nm (96 ftlb).

Note

If required, fit dial gauge holder with Ate conversion kit, Part No. 03.9314-5510.3/01 (longer wing screw and bracket for dial gauge if required).

4. Fit dial gauge with a slight preload. Place measuring pointer on maximum diameter of braking surface.

3. Engage dial gauge holder, e.g. Ate Part No. 03.9314-5500.3/01, into brake caliper, determine center position and fit by turning the wing screw.

If the brake disc cannot rotate freely, bush back brake pads slightly. Take care not to damage the tab for the spreader spring on the retainer plate of the four-piston fixed calipers when fitting the dial gauge holder.

5. Rotate brake disc and read off runout on dial gauge.

Max. permissible lateral runout of fitted brake disc max. 0.1 mm.

Note

Lateral runout of removed brake disc : max. 0.05 mm.

Lateral runout of wheel hub : max. 0.05 mm.

6. If the brake disc runout exceeds 0,1 mm, remove the brake disc and check lateral runout of the wheel hub. Mark position of disc with regard to wheel hub.

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VW 387

7. Check wheel hub runout as follows: Measure once outside (arrow) and once within wheel stud area of hub face. Lift off dial gauge carefully in cutout area of hub. To fit the dial gauge, use either a magnetic universal dial gauge holder or the dial gauge holder VW 387.

Note

Make sure the brake hoses and brake pipes are not damaged when the brake caliper is removed and installed.

8. Excessive lateral runout of wheel hub:

Replace wheel hub.

Lateral runout of wheel hub o.k.:

Clean leveling and centering surfaces of brake disc and wheel hub. Then coat centering surfaces of wheel hub with a thin coat of Optimoly TA.

Fit brake disc to wheel hub in another position, offset radially with regard to wheel hub. Repeat measurements with fitted adapter plate - Special Tool 9510/1. If the lateral runout is still in excess of 0.1 mm, the brake pad must be replaced.

Note

If the brake disc runout has been reduced by offsetting the brake disc radially with regard to the wheel hub, one 6 mm screw may be omitted if two 6 mm countersunk screws had been fitted.

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/C PyjÇU^

Do It Yourself Car Diagnosis

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