1942 - 1947 Chevrolet Shop Manual



	*10-6*

	the pendulum swings over the line between the "poor" and "danger" zones. The adjusting rod and weight are used in connection with each other to calibrate the sensitivity of the machine. NOTE-The machine should be calibrated each time a different wheel is balanced. When the adjusting rod is removed from the arbor, the pointer should return over the center line. If it does not, turn the wheel a few inches in either direction until the pointer is directly over the center line. With the pendulum weight properly calibrated, we are now ready to balance the wheel. Replace the adjusting rod on arbor with mark "1" directly in line with mark on end of arbor and then chalk the tire directly below the rod. Without moving the wheel, turn the adjusting rod so that mark "2" is directly in line with the mark on the arbor, and again chalk the tire directly below the rod. Again, turn the adjusting rod 90° to the third position and make a third chalk mark on the tire. Repeat this operation and make a fourth chalk mark on the tire. Now, with the adjusting rod still on the arbor with one of the marks lined up with the mark on the arbor, turn the wheel assembly 90^c (1/4 turn) and then remove the adjusting rod. Indicator pointer at bottom of pendulum will now show condition of the static balance of the wheel assembly. Place necessary weight (or weights) on rim of wheel at chalk mark on right (or high) side of wheel until pointer returns to center line. If two weights are required, they should be placed at equal distances from chalk mark. When proper weight has been determined, fasten securely to rim of wheel. After the wheel assembly has been statically balanced, it should be rotated in short steps, making a complete turn to determine whether the assembly is now balanced statically in all positions. CHECKING FOR DYNAMIC BALANCE A dynamic balancer is composed of the dynamic arbor and leveling plate assembly. The leveling plate assembly is in turn composed of the floating spindle integral with the ball which forms the leveling plate seat, the leveling plate and the mounting cones. (See Fig. 12.) In operation the leveling plate assembly floats free of the dynamic arbor so that any wobble in the wheel will be shown. The leveling plate is a snug fit on its ball seat so that it rotates with the wheel, but may be tilted up or down in relation to the spindle. After the wheel assembly has been statically balanced, it is ready for dynamic balancing. With the wheel bearings in place, lower the wheel as-
		Fig. 12-Installing Leveling Plate sembly onto the dynamic spindle with the brake drum down. Place the small cone over the spindle and adjust the nut snugly so the spindle will rotate with the wheel and not turn separately. Adjust motor height so that the drive pulley contacts the center of the tire; start motor and revolve wheel for 20 or 30 seconds, after which the motor can be switched off and the pulley released from contact with the tire. When a wheel revolves at high speed on a floating spindle, any uneven weight distribution will cause the wheel and floating spindle to change its axis of rotation so that the center line of the weight mass becomes horizontal-or perpendicular-in relation to the dynamic arbor, just as the weight on the string became perpendicular in relation to the hand. With the wheel still revolving at high speed, carefully raise the leveling handle until the fibre button contacts the leveling plate continuously and the plate runs true. Then lower the leveling handle and apply the brake to the tire in order to bring the wheel to a complete stop. When leveled in this manner, the leveling plate is brought into parallel with the center line of the wheel mass, but not necessarily in parallel to the wheel itself because if the wheel was dynamically out of balance, the wheel and leveled plate are not in parallel. Raise the indicator hub carefully into the arbor socket, lifting it as far as possible and holding it there firmly. This operation brings the wheel into perpendicular with the dynamic arbor, and at the same time tilts the leveling plate so that it now has the same tilt or wobble that was formerly in the spinning wheel. Thus, when a reading is taken from the leveling plate, it will show the amount and location of the dynamic unbalance in the wheel.