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Home >> Porsche >> 2014 >> Boxster Base, Automatic DCT Trans >> Repair and Diagnosis >> Brakes >> Mechanical - Hydraulic >> 46 - Brakes - Brake Mechanics -- (981) BOXSTER/CAYMAN >> WM 465004 Measuring Front Brake Discs (All Models) >> Measuring Brake Discs/Wheel Hubs

Measuring Brake Discs/Wheel Hubs

Information 

Measuring the brake disc includes: 

Enter measured values in the brake disc measurement sheet. →  4X00IN BRAKE DISC MEASUREMENT SHEET 

  1. Measure the lateral runout of the brake disc (with adapter plate fitted)  .
    1. 1.1. Fit special tool -1- adapter plate 9510/1  with standard wheel bolts on the wheel hub. Tightening torque 160 Nm.
    2. 1.2. Fit the measuring equipment -2- dial gauge set with ball joint arm Nr.147-1  at a suitable position on the wheel bearing housing.
    3. 1.3. Fit the dial gauge -2-  with some preload and measure the lateral runout at the greatest external diameter of the brake disc.

      Max. permitted brake disc lateral runout = 0.06 mm. →  4X00IN TECHNICAL DATA/BRAKE WEAR LIMIT 

      Fig 1: Measuring Brake Disc Lateral Runout
      G10026588Courtesy of PORSCHE CARS NORTH AMERICA, INC.
  2. Measure the wheel hub lateral runout  .
    1. 2.1. Remove the front brake disc. → 465019 REMOVING AND INSTALLING THE FRONT BRAKE DISC 
    2. 2.2. Fit the measuring equipment dial gauge set with ball joint arm Nr.147-1  at a suitable position on the wheel bearing housing. Fit the dial gauge with some preload.

      Information 

      The front face of the wheel hub must not be corroded. If necessary, clean with fine emery cloth.

    3. 2.3. Measure the wheel hub lateral runout at the front face of the wheel hub. To do this, always take measurements at the external and internal diameter of the wheel bolt area -arrows-  (5 measuring points each).

      Max. permitted wheel hub lateral runout = 0.03 mm. →  4X00IN TECHNICAL DATA/BRAKE WEAR LIMIT 

      Fig 2: Locating Wheel Hub Measuring Points
      G10026589Courtesy of PORSCHE CARS NORTH AMERICA, INC.
  3. Measure the brake disc thickness tolerance  .
    1. 3.1. Using a suitable micrometer screw gauge, measure the thickness tolerance at 8 points within the braking surface. Thickness tolerance of brake disc: maximum 0.02 mm. (New brake disc = max. 0.01 mm). →  4X00IN TECHNICAL DATA/BRAKE WEAR LIMIT 
  4. Procedure in the event of different lateral runout measured values: 
    1. 4.1. Wheel hub lateral runout is too large: Replace the wheel hub.
    2. 4.2. Wheel hub lateral runout is OK, but lateral runout on brake disc (measured with brake disc fitted on wheel hub) is not OK:
      • Clean the levelling and centering surfaces on the brake disc and wheel hub. Then apply a very thin coat of Optimoly TA (aluminum paste) to the centering surface on the wheel hub.
      • Offset the brake disc radially with respect to the wheel hub (matching/secure on the wheel hub at a different position than before). One of the two M6 countersunk screws can be left out in this case.
      • Repeat the measurement with adapter plate 9510/1  fitted. If the lateral runout is still greater than 0.06 mm, replace the brake disc.
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