VW Passat & Audi A4 1990-2000

Brake Disc (Rotor)

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REMOVAL & INSTALLATION

NOTE
If the brake rotors are directional rotors, they are different from side to side. To differentiate from side-to-side, the left side brake rotor part number ends in an odd number, the right side rotor part number ends in an even number.


WARNING
The balancing clips in the venting of the rotor must not be moved or removed. This will cause an imbalance of the rotor.

  1. Block the rear wheels and apply the parking brake.
  2.  
  3. Loosen the front wheel bolts 1 / 8 turn.
  4.  
  5. Raise and support the vehicle. Remove the front wheels.
  6.  


NOTE
Do NOT loosen or disconnect the brake caliper fluid hose. Once removed, support the caliper assembly with mechanic's wire to avoid damaging the line.

  1. Remove the brake caliper as outlined in this section.
  2.  
  3. If equipped, remove the brake caliper bracket as outlined in this section.
  4.  
  5. If equipped, remove the brake disc retaining fastener. If equipped with a Phillips screw, it may be necessary to remove the screw using a hand impact driver and a suitable Phillips bit. If the fastener is corroded in place, spray it with a penetrating lubricant and use a hand impact driver to loosen.
  6.  
  7. Remove the brake rotor. If the brake rotor is seized in place;
  8.  
    1. If equipped, remove the brake rotor retaining bolt.
    2.  
    3. Spray a penetrating lubricant around the rotor-to-hub seam.
    4.  
    5. Install 2 wheel bolts approximately 10 turns and using a suitable hammer, rap sharply on the flat surface of the flat wheel-to-brake rotor-to-hub surface. Do NOT contact the machined area of the brake pad-to-rotor surface. The shock from the impact should eventually loosen the brake rotor from the hub.
    6.  




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Fig. If the brake rotor is retained by a Phillips screw, use a hand impact driver and a suitable bit to loosen it



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Fig. If the brake rotor is seized onto the front hub, spray a penetrating lubricant around the rotor-to-hub seam, then install 2 lug bolts and . . .



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Fig. . . . using a suitable hammer, rap sharply on the flat surface of the brake rotor. The shock from the impact should eventually loosen the rotor



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Fig. Clean the hub, then before installing the brake rotor, apply a light coat of anti-seize compound

To install:

  1. Check the rotor and replace as necessary.
  2.  
  3. If a new rotor is to be installed, make sure the rotor is free of any protective coatings. Remove the protective coating as recommended by the manufacturer.
  4.  
  5. Clean the hub and brake rotor surfaces, then before installing the brake rotor, apply a very light coat of an anti-seize compound.
  6.  
  7. If equipped, install the brake rotor retaining fastener and tighten to 12 ft. lbs. (16 Nm).
  8.  


WARNING
If equipped, the brake rotor fastener must be reinstalled. If damaged or missing, replace. Failure to install the fastener could result in the lug bolts being sheared off during hard braking.

  1. The balance of the installation is in reverse order of removal noting the following steps.
  2.  
  3. Install the wheels and hand tighten the lug bolts. Lower the vehicle carefully until the tires begin to contact the surface and torque the lug bolts to specification in a crisscross pattern to:
  4.  
  5. M12 x 1.5 lug bolts: 81 ft. lbs. (110 Nm)
  6.  
  7. M14 x 1.5 lug bolts: 89 ft. lbs. (120 Nm)
  8.  


WARNING
Failure to properly torque the wheels to the correct torque using the proper sequence could cause a brake pulsation and rotor warpage.

  1. Press the brake pedal down slowly about 2 inches (50mm), then slowly release. Continue to press and release the brake pedal in slow even 2-inch (50mm) strokes until the pedal is firm.
  2.  
  3. Burnish the rotors by making 5 full stops from 30 mph (50 km/h), and then allow the brakes to cool. Make 5 additional stops from 30 mph (50 km/h) and allow the brakes to cool again. This will burnish the rotors and allow full braking efficiency.
  4.  

Inspection

Visually inspect the brake rotor machined surface. Replace the brake rotor if:



The surface is pitted
 
The surface is cracked
 
The surface is uneven or grooved
 
There is an excessive ridge on the outer circumference
 

The brake rotors should be measured for warpage and thickness variation. If a brake pulsation is felt through the brake pedal during braking, there is likely a thickness variation in one or more of the brake rotors. If a brake pulsation is felt through the brake pedal and the steering wheel during braking, there is likely a thickness variation in one or more of the front brake rotors and possibly the rear brake rotors.

If a brake pulsation is felt through the steering wheel, but not through the brake pedal during braking, one or both of the front brake rotors is likely to be warped.

Whenever the brake calipers or pads are removed, inspect the rotors for defects. The brake rotor is an extremely important component of the brake system. Cracks, large scratches or warpage can adversely affect the braking system, to the point of becoming very dangerous.

Light scoring is acceptable. Heavy scoring or warping will necessitate refinishing or replacement of the disc. The brake disc must be replaced if cracks or burned marks are evident.

If the rotor needs to be replaced with a new part, the protective coating on the braking surface of the rotor must be removed with an appropriate solvent before installing the rotor to the vehicle.

Check the run-out of the hub (disc removed). It should not be more than 0.002 inch (0.05mm). If so, the hub should be replaced.

All brake discs have markings for MINIMUM allowable thickness cast on an un-machined surface or an alternate surface. Always use this specification as the minimum allowable thickness or refinishing limit. Refer to a local auto parts store or machine shop, if necessary, where rotors are resurfaced.

If the rotor needs to be replaced with a new part, the protective coating on the braking surface of the rotor must be removed with an appropriate solvent before installing the rotor to the vehicle.

To properly check a brake rotor, the disc runout, thickness and parallelism should be measured. To perform these measurements proceed as follows:

  1. Raise and safely support the vehicle.
  2.  
  3. Remove the tire/wheel assembly for the brake rotor to be inspected.
  4.  
  5. Reinstall the lug bolts with washers and torque to 80 ft. lbs. (108 Nm).
  6.  
  7. Remove the brake pads as outlined in this section.
  8.  
  9. Inspect the brake surface for cracks and damage, then thoroughly clean the brake surface.
  10.  
  11. To measure runout:
  12.  
    1. Attach a dial indicator to a solid portion of the suspension.
    2.  
    3. Set and zero the dial indicator plunger 0.40 inches (10mm) inside the outer circumference of the brake rotor.
    4.  
    5. Rotate the brake rotor and note the amount of runout by reading the dial indicator. If the runout exceeds 0.004 inch (0.10mm), measure the minimum thickness. If rotor thickness is within specification, use an approved on-car brake lathe or remove the rotor and machine.
    6.  

  13. To measure the brake rotor thickness and parallelism proceed as follows:
  14.  
    1. Use a micrometer and measure the brake rotor thickness 0.40 inches (10mm) inside the outer circumference of the brake rotor every 45° ( 1 / 8 turn).
    2.  
    3. Compare the smallest value measured to the minimum thickness specifications stamped on the brake rotor. If the rotor is below the minimum thickness, the rotor must be replaced. If within specification, measure the parallelism.
    4.  
    5. To measure parallelism, subtract the smallest value measured from the largest value measured. The parallelism should be less than 0.0008 inch (0.02mm). If the parallelism is greater than 0.0008 inch (0.02mm), and within the minimum thickness specification use an approved brake lathe and machine the brake rotor.
    6.  



NOTE
If after machining the brake rotor is below minimum thickness, it must be replaced.



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Fig. Using a micrometer to measure the thickness of the brake rotor. Discard the rotor if it is not within the specification stamped on the rotor



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Fig. Use a dial indicator to measure the brake rotor runout



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Fig. Use a micrometer to determine the rotor parallelism and to measure rotor thickness. If the rotor thickness is below the minimum thickness, it must be replaced

 
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