Lateral Runout

Measuring the front brake disc lateral runout

Includes: Measuring the brake disc thickness

1. Measuring requirement: No tilt play at the wheel.





2. Fit the adapter plate (special tool 9510/1) to the wheel hub. Tightening torque of the wheel bolts (fastening screws) 130 Nm (96 ft. lbs.).
3. Insert dial gauge holder, e.g. Ate order No. 03.9314 - 5500.3/01, into the brake caliper, align it and secure it by turning the clamping wing screw. If the brake disc cannot be turned freely, set the brake pads back a little. Do not damage the spreader spring when fitting the dial gauge holder.

Note If necessary, provide the dial gauge holder with the Ate conversion set, order No. 03.9314 5510.3/01 (longer clamping wing screw and, if necessary, also a bracket for the dial gauge).





4. Secure the dial gauge with some preload. Put the measuring tip against the largest diameter of the braking surface.
5. Turn the brake disc and, when doing so, read off the lateral runout on the dial gauge. The permissible lateral runout for the installed brake disc is maximum 0.06 mm.

Note Lateral runout of the removed
^ brake disc: maximum 0.03 mm.
^ Wheel hub lateral runout: maximum 0.03 mm.

6. If the brake disc lateral runout exceeds 0.06 mm, remove the brake disc and check the wheel hub lateral runout. First mark the position with respect to the wheel hub.
7. Check the wheel hub lateral runout as follows: Measure 1 x outside (arrow) and 1 x inside (arrow) of the wheel bolt area (5-point measuring procedure) on the front face of the wheel hub. Use a universal dial gauge holder, e.g. from SNAP - ON (order No. PMF 137), to secure the dial gauge.

Note Do not damage the brake hoses or brake lines during removal/installation of the brake caliper.





The above SNAP - ON order number PMF 137 applies to a complete dial gauge set, because the dial gauge is not available on its own. The dial gauge set can also be used to check the brake disc lateral runout.

8. Wheel hub lateral runout too great:
Replace the wheel hub.
Wheel hub lateral runout in order:
Clean the levelling and centering surface on the brake disc and wheel hub. Next, apply a very thin coat of Optimoly TA to the centering surface on the wheel hub.
Secure the brake disc to the wheel hub in a different position to the one before and offset radially with respect to the wheel hub.
Repeat the measurement with the fitted adapter plate - special tool 9510/1. If the lateral runout is still greater than 0.06 mm, replace the brake disc.

Note If the brake disc lateral runout was reduced by radially offsetting the brake disk with respect to the wheel hub, one M6 screw can be left off, provided that two M6 countersunk screws were fitted.

Measuring the brake disc thickness tolerance
Measure the brake disc thickness deviation within the braking surface at approximately 8 points by using the micrometer. Thickness tolerance of the brake disk maximum 0.02 mm (new condition maximum 0.01 mm).