For 1990-2009 cars

# INFO. ON COSMETIC DAMAGE TO ALUMINUM WHEELS DURING BALANC.

REVISION 06/04/93

THIS BULLETIN IS BEING REVISED TO SPECIFY GMC/CHEVROLET TRUCK INFORMATION ONLY AND ADD MODEL YEARS 1985-87. ---------------------------------------------------------------------- SOME ALUMINUM WHEELS ON GM MODELS MAY INCUR COSMETIC DAMAGE DURING BALANCING IF PROPER CARE AND PROCEDURES ARE NOT USED. ALL ALUMINUM WHEELS HAVE A CLEARCOAT PAINT ON THEM THAT MUST BE CARED FOR LIKE ANY OTHER PAINTED SURFACE.

SOME OFF-CAR WHEEL BALANCER RETAINING CUPS USED TO CLAMP THE WHEEL TO THE BALANCER MAY PUT A CIRCULAR MARK INTO THE CLEARCOAT ON THE FACE OF THE WHEEL. LIKE ANY OTHER CLEARCOAT DAMAGE, THIS MAY BE DIFFICULT TO REMOVE OR REPAIR, DEPENDING ON SEVERITY.

ALWAYS USE BALANCER RETAINER CUPS THAT ARE PROTECTED WITH RUBBER, PLASTIC, OR OTHER NONMETALLIC MATERIALS WHERE CONTACT IS MADE WITH THE WHEEL. MAKE SURE THE RETAINER CUP IS FREE FROM DIRT, GREASE, AND GOUGES. MOST WHEEL BALANCERS NOW OFFER THIS TYPE OF PROTECTED RETAINER.

DO NOT ALLOW THE RETAINER CUP TO ROTATE AGAINST THE WHEEL'S SURFACE WHEN TIGHTENING THE WHEEL TO THE BALANCER.

DO NOT OVERTIGHTEN. MOST BALANCERS USE A LARGE "WING NUT" DESIGN TO CLAMP THE RETAINER AGAINST THE WHEEL. HAND TIGHT IS SUFFICIENT.

THIS PROCECURE WILL ALLOW ACCURATE BALANCING USING THE CONVENTIONAL BACK CONE METHOD.

#### IMPORTANT: COATED BALANCE WEIGHTS MUST BE USED ON ALUMINUM WHEELS TO PREVENT DAMAGE TO THE RIM FLANGE.

GMC AND CHEVROLET TRUCK INFO ONLY: EXCEPT FOR THE N90 4X4 WHEEL USED ON T TRUCKS, ALL LIGHT TRUCK ALUMINUM WHEELS WILL ACCEPT EITHER "AW" SERIES OR "MC" SERIES CLIP ON COATED WEIGHTS ON BOTH THE INSIDE AND OUTSIDE RIM FLANGES. THE N90 T TRUCK WHEEL WILL ACCEPT "AW" SERIES WEIGHTS ON THE INSIDE RIM FLANGE ONLY. THE OUTSIDE RIM FLANGE IS NOT DESIGNED TO ACCEPT A CLIP-ON WEIGHT. IF SUCH A WEIGHT INSTALLATION IS ATTEMPTED, A POOR FIT WILL RESULT, AND THE WEIGHT MAY FALL OFF AND/OR CAUSE COSMETIC DAMAGE TO THE RIM FLANGE. THIS WHEEL CAN BE 1) STATIC BALANCED BY CLIPPING ALL THE WEIGHT ON THE INSIDE RIM FLANGE (AS IS DONE IN THE ASSEMBLY PLANT), OR 2) DYNAMIC BALANCED BY CLIPPING A WEIGHT ON THE INSIDE FLANGE AND USING AN ADHESIVE WEIGHT NEAR THE OUTSIDE FLANGE.

THE ATTACHED CHARTS SHOW "AW" AND "MC" BALANCE WEIGHT USAGE. THESE ORIGINAL EQUIPMENT COATED WEIGHTS ARE AVAILABLE AT COMPETITIVE PRICES THROUGH THE GM DEALER EQUIPMENT PROGRAM.

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE 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 A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.

MOPYRIGHT 1993 GENERAL MOTORS CORPORATION. ALL RIGHTS RESERVED.