Document ID# 2056386
Subject: Brake Align System for Brake Rotor Lateral Runout Correction #01-05-23-001B - (01/31/2008)
Models: 2008 and Prior Passenger Cars
This bulletin is being issued to update General Motors' position on correcting brake rotor lateral runout (Refer to Corporate Bulletin Number 00-05-22-002B for additional brake rotor service procedures).
Important: Certain conditions may apply to individual vehicles regarding specific repairs.
Refer to those specific repairs in applicable service bulletins. Make sure other possible sources of brake pulsation, such as ABS pedal feedback, have been addressed before checking rotor runout.
Anytime a new or refinished rotor is installed on a vehicle, the rotor must have .050 mm (.002 in) or less of lateral runout. This specification is important to prevent comebacks for brake pulsation.
Until now, the only acceptable methods to correct brake rotor runout were to index or replace the rotor or to refinish the rotor using an on-vehicle brake lathe.
GM has approved a new technology for the correction of lateral runout on new or refinished rotors. This new method is called Brake Align®*.
It will allow the technician to meet the .050 mm (.002 in) or less requirement for lateral runout by installing a specially selected, tapered correction plate between the rotor and the hub. The Brake Align® Correction system does NOT require the use of an on-vehicle brake lathe to correct for lateral runout.
*We believe this source and their products to be reliable. There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any such items which may be available from other sources.
The Brake Align® Starter Kit will include an ample supply of Correction Plates, in various correction sizes, that will cover most current GM passenger car applications. It will also include a Brake Align® tool kit containing a dial indicator and retaining washers along with other useful tools.
Follow all the procedures referred to in Corporate Bulletin Number 00-05-22-002B. Dealers who have purchased the Brake Align® Starter Kit may use the following simplified runout correction procedure:
The existing rotors must first be machined on an approved, well-maintained bench lathe to guarantee smooth, flat, and parallel surfaces.
Should the rotors require replacement, please note that it is not necessary to machine new rotors.
Make sure all the mating surfaces of the rotor and the hub are clean, using the J 42450-A Wheel Hub Cleaning Kit. Mount the new or refinished rotor onto the vehicle hub using the retaining washers provided in the kit. Do not reinstall the caliper or wheel at this time.
Tighten all the wheel nuts to the proper specification, using J 39544 Torque Socket or the equivalent.
Fasten the dial indicator to the steering knuckle so that the indicator needle contacts the rotor friction surface approximately 12.7 mm (1/2 in) from the rotor's outer edge.
Rotate the rotor and observe the total lateral runout.
Index the rotor on the hub to achieve the lowest amount of lateral runout. This will require removal and reassembly of the rotor until the lowest total lateral runout reading is obtained. If this reading is .050 mm (.002 in) or less, the assembled rotor is within specification. The brake system may be reassembled.
If total lateral runout is greater than .050 mm (.002 in), proceed with determining the correct Brake Align® Correction as follows:
• Rotate the rotor to locate the lowest dial indicator reading and set the dial to zero.
• Rotate the rotor to determine and locate the highest amount of lateral runout.
• Note the AMOUNT and LOCATION of the "high spot" on the rotor and mark the closest wheel stud relative to this location.
Remove the rotor.
Select the appropriate Brake Align® Runout Correction Plate for this vehicle using the included Application Chart.
Make sure the selection corrects the amount of runout that was diagnosed.
Important: Never attempt to stack two or more Correction Plates together on one hub.
Never attempt to re-use a previously installed Correction Plate.
Following the Brake Align® procedures and diagram, install the Correction Plate onto the vehicle between the hub and the rotor. The V-notch in the Correction Plate is to be installed and aligned with the noted location of the "high spot" on the vehicle hub and marked wheel stud.
Install the rotor onto the vehicle with the Correction Plate placed between the hub and the rotor. Be sure to install the rotor onto the hub in the same location as identified in Step 7.
The rotor should then be secured onto the hub and tightened to the proper specification.
The rotor should be dial indicated once more to assure that the rotor is now within specification.
The brake system is now ready for the remaining service and assembly. Once the caliper has been installed, check to ensure that the rotor rotates freely