ALL SUBARU MODELS
BRAKE VIBRATION DIAGNOSIS AND REPAIR
When encountering a customer complaint of brake vibration on any Subaru vehicles, the procedures are required to ensure a proper repair.
BRAKE ROTOR RESURFACING PROCEDURE
Resurfacing rotors with excessive run out is best done on the vehicle when possible, using a Twin Arbor Vehicle-Mounted Brake Lathe, such as the Ammco 710 model.
- When using an on-the-vehicle resurfacing lathe:
- Measure the thickness of the rotor after resurfacing to confirm if it's within specification. (See specifications)
- If the thickness is less than specification, replace the rotor with a new one.
- Run out doesn't need to be re-checked after resurfacing the rotor when using the on-the-vehicle resurfacing lathe.
- When using an off-the-vehicle resurfacing lathe. (i.e. Ammco Model 4000). (This method is not recommended.)
- Remove rust and foreign material completely from mounting area of rotor using solvent or wire brush.
- Secure the rotor on both sides and mount rotor using a centering cone. See Figure 1.
- Measure the thickness of the rotor after resurfacing to confirm it is within specification. (See specifications)
- Reinstall the brake rotor on the vehicle using all lugs. Install the lugs with their flat side in and tighten slightly, using a socket or wrench, then re-check run out.
- If rust was evident before resurfacing the rear rotor, replace the brake pads using Part Numbers: 26296AA061 for Legacys with Solid Rotors and 26296AA081 for Legacys with Ventilated Rotors.
CHECKING PROCEDURE FOR BRAKE ROTOR RUN OUT
The rotor specifications should be used to determine if a rotor is to be replaced or resurfaced.
- Measure free play of bearing by pushing and pulling hub in an axial direction.
Mount rotor to the hub securely with all lugs, flat side in and tighten slightly, using a socket or wrench.
- Confirm free play of bearing in an axial direction is 0.05 mm or less.
- Front wheel bearing free play on all models except Legacy, SVX, and XT6 is not required to be measured due to the ball bearing design.
- Clean pad contact surfaces of rotor (especially where measurement will be taken).
- Attach dial indicator gauge on caliper mount or strut and measure maximum run out of rotor on both sides at a point of 5 mm inside from the circumference of rotor by rotating rotor gradually. See Figure 2. Run out is best checked when the rotor is cool. (See specifications.)
- In case the run out of a new or resurfaced rotor is out of specification when re-checking, relocate the rotor to another position on the hub and re-check run out. Repeat the process of relocating the rotor to compensate for minor run out variations between the rotor and hub.
- If relocating the rotor does not correct run out, check the hub run out for inaccuracy and repair as necessary.
BRAKE SERVICE FACTS
- Brake rotors can be resurfaced more than once for poor run out or thickness variation if still within the minimum thickness standard after resurfacing.
- Brake rotor discoloration or visible brake pad imprints on the rotor, do not warrant brake rotor replacement.
- Resurfacing or replacing rotors is not necessary unless a vibration complaint is confirmed or the rotor is scored because a brake pad was allowed to wear to the backing plate.
- Never resurface or remove the zinc coating on a new rotor. The zinc coating will be eliminated after the first few stops.
- Resurfacing rotors is not a recommended repair for brake noise.
- Brake pads should be reused if not worn to their limit when a brake rotor is replaced or resurfaced for vibration.
- A major cause of brake vibration is inaccurate rotor resurfacing due to incorrect rotor lathe mounting and a brake lathe with excessive shaft run out.
- When brake pads are worn to the minimum limit and brake pad replacement is necessary, only replace the brake pads. Rotor replacement or resurfacing is not necessary.
- For any brake repair procedure always inspect the brake system for abnormalities. Example: Sticking or binding caliper, tight or binding pads, uneven wear, rust, foreign material, lack of lubrication, etc.