Measuring the front brake disc lateral runout: Notes

Includes: Measuring the brake disc thickness tolerance

Measuring prerequisite: No tilt play at the wheel.

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, possibly, also a bracket for the dial gauge).
Do not damage the expanding spring when fitting the dial gauge holder.

Mount the adapter plate 9510/1 on the wheel hub. Tightening torque of the wheel bolts (fastening screws): 130 Nm (96 ftlb.).

Fig 1: Identifying Adapter Plate 9510/1
Courtesy of PORSCHE OF NORTH AMERICA, INC.
Insert dial gauge holder, for example, ATE order No. 03.9314-5500.3/01, into the brake caliper, align it and secure it by tightening the clamping wing screw. If the brake disc cannot be turned freely, set the brake pads back a little.
Secure the dial gauge with some preload. Put the measuring tip against the largest diameter of the brake surface.

Fig 2: Checking Brake Disc Lateral Runout With Dial Indicator
Courtesy of PORSCHE OF NORTH AMERICA, INC.
Turn the brake disc and, when doing so, read off the lateral runout at the dial gauge.
NOTE:
- Lateral runout of the removed brake disc: max. 0.03 mm!
- Wheel hub lateral runout: max. 0.03 mm!
- The permissible lateral runout of the installed brake disc is max. 0.06 mm!
- Do not damage the brake hoses or brake lines during removal/installation of the brake caliper!
If the brake disc lateral runout exceeds 0,06 mm, mark the position in relation to the wheel hub and remove the brake disc. Check the wheel hub lateral runout.
Check the wheel hub lateral runout as described below: 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. Fasten the dial gauge using a commercially available universal dial gauge holder.

Fig 3: Measuring Wheel Hub Lateral Runout At Outside & Inside Of Wheel Bolt Area
Courtesy of PORSCHE OF NORTH AMERICA, INC.

Wheel hub lateral runout is too large:

Replace the wheel hub.

Wheel hub lateral runout OK:

Clean the levelling and centring surfaces on the brake disc and wheel hub. Next, apply a thin coat of Optimoly TA to the centring surface on the wheel hub. Fasten brake disc on the wheel hub in a different position than before - radially offset with respect to the wheel hub. Repeat the measurement with adapter plate 9510/1 fitted. If the lateral runout is still greater than 0.06 mm, replace the brake disc.