1995 - 2002 Corvette: Service Bulletin: Warranty Admin. - Brake Rotor Warranty Service Procedure


Number: 00-05-22-002A
Subject: Brake Rotor Warranty Service Procedure
Model Year: 1995-2002 Passenger Cars and Light Duty Trucks

This bulletin is being revised to add model years, change the service category and update the information. Please discard Corporate Bulletin Number 00-05-22-002 (Section 05 - Brakes).

This bulletin outlines GM's standard procedures and guidelines for brake rotor service and brake wear. Brake rotor service to correct scoring or pulsation is covered by the GM New Vehicle Limited Warranty unless there is evidence of the vehicle being subject to severe use.

Important
Certain conditions may apply to individual vehicles regarding specific repairs which differ from those outlined in this bulletin. For information regarding lateral runout correction, refer to Corporate Bulletin Number 01-05-23-001, Brake Align System for Brake Rotor Lateral Runout Correction. For other conditions, refer to those specific repairs in applicable bulletins.

Original equipment rotor surfaces are ground to ensure smooth finish and parallelism between mounting and friction surfaces. New rotors SHOULD NOT be resurfaced before installation. When rotor turning is necessary, it is essential that you use a high quality brake lathe. Rotors, when remounted on the hub, should have less than .055 mm (.002 in) lateral runout. Brake rotors should only be turned when one of the following rotor surface conditions exist:

    1. Severe scoring -- depth in excess of 1.5 mm (0.060 in).
    2. Pulsation concerns from:



Rotors are not to be resurfaced in an attempt to correct the following conditions:


Explanation of Brake Rotor Warranty Service Procedure

 


Brake Service Techniques

  1. Clean and lubricate all metal-to-metal contact points (i.e. caliper to knuckle, pad to knuckle, etc).
  2. Clean and lubricate slide pins, if applicable.
  3. Set correct clearances (i.e. caliper to knuckle, etc), if applicable.
  4. Clean rotor and hub mounting surfaces. Use Kent Moore tool J-42450 to clean around the wheel studs.
  5. Verify lateral runout of the rotor with a dial indicator (rotor held on hub with 3 or more wheel nuts and washers).

    Important
    Refer to the appropriate Service Manual for more specific procedures.


Pulsation

Important
Brake pulsation is often caused by factors outside customer control. In these instances, the repair is covered under the GM New Vehicle Warranty.

Brake pulsation concerns may result from two basic conditions:


GM highly recommends the use of on-car brake rotor turning as a method of eliminating the stack up of lateral runout which is a potential source of brake pulsation. GM has identified superior equipment through testing and evaluation. The *Pro-Cut PFM900 or Hunter OCL360 will consistently deliver machined rotors that meet GM specifications (lateral runout less than .055 mm (.002 in) and are the only on-car brake lathes that are currently recommended by GM. The use of this on-car rotor turning technology has proven to significantly reduce the repeat occurrences of brake pulsation. If on-car brake rotor turning equipment is not available, refer to Corporate Bulletin Number 01-05-23-001 for brake rotor lateral runout correction procedure.

*We believe these sources and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the equipment from this firm or for any such items which may be available from other sources.

The following are examples of pulsation conditions and reimbursement recommendations:

  1. If a customer noticed the condition after 4800-11300 kilometers (3000-7000 miles) and it gradually got worse, normally the repair would be covered. The customer may tolerate the condition until it becomes very apparent.
  2. If a customer indicated they had wheel service, ask who performed the service. Then:


Customer assistance concerning brake pulsation and brake wear should always take into account the individual circumstances on a case by case basis. The recommendations mentioned previously should only be used as a general guide. REMEMBER THAT CUSTOMER SATISFACTION IS CRITICAL TO GM AND THAT OFTEN IT IS IN GM'S BEST INTEREST TO SATISFY AND EDUCATE THE CUSTOMER CONCERNING FUTURE BRAKE SERVICE.

Rotor Grooving
Excessive grooving can be caused by foreign material in contact with the rotor, but most often rotor grooving is the result of normal brake wear. Do not resurface rotors for light grooving. Resurface rotors only when grooves of 1.5 mm (0.060 in) or deeper are present.

A dime may be used to determine disc brake groove depth. Place a dime in the groove, with Roosevelt's head toward the groove. If the dime goes into the groove beyond the top of his head, the groove exceeds 1.5 mm (0.060 in) and the rotor should be serviced. In Canada, if any portion of the letters of "Canada" are covered, the rotor should be serviced. If the groove is too narrow for the dime to be inserted, it is not a cause for concern.

High Pedal Effort
Follow the Service Manual diagnostic procedures for this condition. Service (replace or resurface) rotors if they have been recently resurfaced. The surface finish may be out-of-specification.

Lightly Rusted Rotors
Light surface rust on rotor braking surfaces is often cosmetic and can be eliminated during a few normal driving stops. Rusting may occur when a vehicle is not driven for extended periods. Rotors with surface rust on unsold new cars can usually be burnished clean by performing 15 moderate stops from 62-75 km/h (35-40 mph) with cooling time between stops.

Facts About Brake Noise
Brake noise is normal and differences in loading, type of driving, or driving style can make a difference in brake wear on the same make and model. Depending on weather conditions, driving patterns and the local environment, brake noise may become more or less apparent.

Brake noise is caused by a "slip stick" vibration of brake components. While intermittent brake noise may be normal, performing 3-4 aggressive stops may temporarily reduce or eliminate most brake squeal. If the noise persists, a brake dampening compound may be applied to the back of each pad. Use Permatex Disc Brake Quiet #126hb, or equivalent. Also, clean and lubricate all metal-to-metal contact areas between pads, pad guides, caliper and knuckles with a thin layer of high temperature silicone grease. This allows parts to slide freely and not vibrate when moving relative to each other.

The following noises are characteristic of all braking systems and are unavoidable. They may not indicate improper operation of the brake system.

Squeak/Squeal Noise


Grinding Noise


Groan Noise
A small groan may be heard when stopping quickly or moving forward slowly from a complete stop. This is normal.

Brake Wear
Several factors impact brake lining wear and should be taken into account when reviewing related issues.
The following are conditions that may accelerate brake lining wear:


The following are conditions that may extend brake lining wear:


GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

© Copyright General Motors Corporation. All Rights Reserv


Article ID: 452
Created On: Wed, Jul 23, 2014 at 9:25 PM
Last Updated On: Wed, Jul 23, 2014 at 9:25 PM

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