LEAD OR PULL TO THE LEFT INSTALL SHIMS OR LEFT MOUNT. Buick Riviera 1990

SOME 1990-1992 ELDORADOS, SEVILLES, ALLANTES, RIVIERAS, AND TORONADOS MAY EXPERIENCE A LEFT LEAD OR PULL CONDITION AT HIGHWAY SPEEDS. LEADS AND PULLS ARE DEFINED AS FOLLOWS:

LEADS: ON A SMOOTH, FLAT (CROWN-FREE) ROAD WITH THE TRANSAXLE IN NEUTRAL, THE VEHICLE DOES NOT REQUIRE A NOTICEABLE TORQUE INPUT TO THE STEERING WHEEL TO MAINTAIN A STRAIGHT PATH. HOWEVER, WITH HANDS REMOVED FROM THE STEERING WHEEL THE VEHICLE DRIFTS TO THE LEFT OR RIGHT.

PULLS: ON A SMOOTH, FLAT (CROWN-FREE) ROAD WITH THE TRANSAXLE IN NEUTRAL, THE VEHICLE REQUIRES A NOTICEABLE TORQUE INPUT TO THE STEERING WHEEL TO MAINTAIN A STRAIGHT PATH.

NOTE: "LEADS" AND "PULLS" ARE TERMS FOR THE SAME CONDITION WITH DIFFERENT LEVELS OF SEVERITY. LEAD REFERS TO THE PATH DEVIATION (USUALLY A LANE CHANGE IN .2 MILES OR LESS WITH HANDS REMOVED FROM THE STEERING WHEEL). PULL INFERS THAT TORQUE IS REQUIRED AT THE STEERING WHEEL TO MAINTAIN A STRAIGHT PATH.

WHEN PERFORMING A DIAGNOSTIC RIDE FOR LEADS AND PULLS IT SHOULD BE DONE ON A SMOOTH, FLAT (CROWN-FREE) ROAD. IT IS ALSO IMPORTANT TO REPEAT THE ROAD TEST IN EACH DIRECTION TO ELIMINATE CROSSWIND AFFECTS. ROAD CROWN AND CROSSWIND INDUCED LEADS AND PULLS ARE NORMAL.

THE LEFT LEAD CONDITION MAY BE CAUSED BY ONE OR ALL OF THE FOLLOWING:

O TIRE LEAD O POWERTRAIN POSITION IN THE VEHICLE O WHEEL ALIGNMENT

THIS CONDITION MAY BE REPAIRED USING THE FOLLOWING PROCEDURE:

1. RAISE CAR ON HOIST.

2. REMOVE BOTH FRONT WHEELS.

3. SUPPORT TRANSAXLE WITH A TRANSAXLE JACK.

IMPORTANT: DO NOT USE A SCREWJACK UNDER THE LIP OF THE TRANSAXLE PAN. THIS COULD CRUSH THE TRANSAXLE PAN GASKET AND RESULT IN TRANSAXLE OIL LEAKS AT A LATER DATE.

4. REMOVE TWO UPPER TRANSAXLE MOUNT NUTS.

5. RAISE POWERTRAIN WITH TRANSAXLE JACK APPROXIMATELY 6 MM.

6. INSTALL A 4 MM SHIM ON THE TOP SIDE OF THE MOUNT BETWEEN THE MOUNT AND TRANSAXLE. A STACK OF SIX ALIGNMENT SHIMS (P/N 14047730, SHIPPED IN PACKS OF 10) MAY BE USED FOR THIS PURPOSE. REFER TO FIGURE 1.

7. LOWER THE TRANSAXLE JACK.

8. INSTALL THE TWO TRANSAXLE MOUNT NUTS AND TORQUE TO 45 N.M (35 LBS. FT.).

IMPORTANT: A MINIMUM CLEARANCE OF 12 MM (.5 INCH) MUST EXIST BETWEEN THE BRAKE LINE BUNDLE AND THE LEFT TRANSAXLE MOUNT BRACKET AFTER INSTALLATION OF THE SHIM. IF NECESSARY, MOVE THE BUNDLE UPWARD TO GIVE ADEQUATE CLEARANCE.

9. CROSS FRONT WHEELS SIDE TO SIDE.

10. LOWER CAR.

11. CHECK AND RESET ALIGNMENT TO THE FOLLOWING SPECIFICATIONS:

FRONT

CASTER 2.3 DEGREES +/- 1.0 DEGREES CROSS CASTER 0.0 DEGREES +/- 1.0 DEGREES CAMBER - LEFT -0.5 DEGREES +/- 0.5 DEGREES CAMBER - RIGHT +0.5 DEGREES +/- 0.5 DEGREES CROSS CAMBER -1.0 DEGREES +/- .75 DEGREES TOE PER WHEEL 0.1 DEGREES +/- 0.1 DEGREES SUM TOE 0.2 DEGREES +/- 0.2 DEGREES STEERING WHEEL ANGLE 0.0 DEGREES +/- 2.5 DEGREES

REAR

TOE PER WHEEL 0.1 DEGREES +/- 0.1 DEGREES SUM TOE 0.2 DEGREES +/- 0.2 DEGREES THRUST ANGLE 0.0 DEGREES +/- 0.1 DEGREES

12. DRIVE THE CAR TO EVALUATE LEFT LEAD CONDITION.

13. IF THE CAR STILL EXHIBITS AN OBJECTIONABLE LEFT LEAD, INSTALL A LEFT TRANSAXLE MOUNT KIT (P/N 22113141). THIS MOUNT KIT HAS LONGER STUDS AND CAN ACCOMMODATE UP TO 8 MM OF SHIM WHICH ARE INCLUDED IN THE KIT. THE SHIMS SHOULD BE INSTALLED ON THE TOP SIDE OF THE MOUNT.

PARTS ARE EXPECTED TO BE AVAILABLE ON JUNE 8, 1992. IN CASE OF LIMITED INVENTORY, PARTS WILL BE PLACED ON 400 CONTROL TO WAIVE VIP SURCHARGES. ONLY VERIFIABLE EMERGENCY VIP ORDERS WILL BE ACCEPTED. SPO WILL MAKE EVERY EFFORT TO OBTAIN PARTS. HOWEVER, THE PART WILL BE SHIPPED PREMIUM TRANSPORTATION AT DEALER'S EXPENSE, AND ALL OTHER ORDER TYPES WILL BE PLACED ON BACK ORDER UNTIL THE 400 CONTROL IS REMOVED.

FOR WARRANTY PURPOSES USE LABOR OPERATION T6634 AT 1.3 HOURS (INCLUDES CAMBER ADJUST). IF A NEW MOUNT IS INSTALLED, ADD 1.0 HOUR.

Object Number: 78904 Size: FS

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.