Checking for lateral run-out and variation in thickness, front wheels

Raise the car and remove the front wheels.
Start by control measuring on one side.
Press in the piston
- Levels 1, 2 and 4: Prise against the brake pad with a screwdriver.
  
  Fig 1: Illustration For Steps 3-4
  Courtesy of SAAB-SCANIA OF AMERICA, INC.
- Level 3: Prise between the brake disc and the brake caliper using a screwdriver.
  
  Fig 2: Illustration For Steps 3-4
  Courtesy of SAAB-SCANIA OF AMERICA, INC.
Remove the brake caliper retaining bolts and lift of the caliper.
NOTE: Make sure the cable to the wheel sensor is not damaged.
Suspend the caliper with cable ties.

Fig 3: Identifying Brake Caliper
Courtesy of SAAB-SCANIA OF AMERICA, INC.
Fit the five wheel bolts with one washer, part no. 80 73 124, on each.

Fig 4: Identifying Wheel Bolts
Courtesy of SAAB-SCANIA OF AMERICA, INC.
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.
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.

Fig 5: Identifying Dial Gauge On Brake Disc
Courtesy of SAAB-SCANIA OF AMERICA, INC.
Rotate the disc and read the gauges. Note the runout (A) and variation in thickness (B).
Check that the readings are within specified intervals, see Specifications .
Remove the dial gauges, brake disc measuring tool and wheel studs with washers.
If runout and thickness variation exceeds specified tolerances, the discs must be machined or replaced. see BRAKE DISC, FRONT .
Fit the brake caliper. Secure the bolts with 74 96 268 Thread locking adhesive.
Tightening torque: 210 Nm +30° (155 lbf ft +30°)

Fig 6: Identifying Brake Caliper Bolts
Courtesy of SAAB-SCANIA OF AMERICA, INC.
Fit the wheel
Repeat this method of measurement on the other brake disc.
Lower the car and depress the brake pedal to press out the brake pads.