Rear Axle Companion Flange Runout Check

1. Raise the vehicle on a hoist that supports the rear axles (twin-post hoist).

2. Remove the driveshaft assembly.

3. Check the companion flange for damage to the universal joint bearing locating lugs. If the lugs are shaved (worn) or damaged, replace the flange.

4. The companion flange runout is checked with a dial indicator with 25.4Omm (1.000 inch) minimum travel, and a cup-shaped dial indicator adapter TOOL-6565-AB or equivalent. To fabricate the checking tool, modify a universal joint assembly by removing two bearing cups that are opposite each other, and cutting or grinding off one of the universal joint bearing flanges.

5. Install the cup-shaped adapter on the dial indicator stem. Install the dial indicator on the pinion nose. Position the indicator to allow an indication at the ends of the universal joint bearing cups and the remaining exposed journal of the cross-shaft.

6. Turn the companion flange so that the dial indicator cup-type adapter rests on the machined surface of the bearing cup. Rotate the companion flange side-to-side slightly to obtain a reading indicating that the bearing cup surface is perpendicular to the adapter. This will be the point at which the dial indicator cup is closest to the center of companion flange rotation. It is also the point at which the dial indicator hand will reverse direction as the companion flange is turning.

7. Carefully retract the dial indicator stem and rotate the companion flange 180° to position the machined surface of the opposite universal bearing under the dial indicator adapter tool. Again, slightly rotate the flange side-to-side to position the bearing perpendicular to the dial indicator adapter. Again, this is the point at which the indicator hand will reverse direction as the flange is rotated. Record the flange bearing cup runout reading obtained from the indicator.

Rotate the companion flange 90° and position the dial indicator adapter on the machined end of the exposed journal. Be sure the end surface of the journal is perpendicular to the adapter. This requires that the cross-shaft be moved fore and aft on the flange bearing cups. Note the point at which the indicator hand reverses direction.

Rotate the flange assembly side-to-side until the cross-shaft is perpendicular to the pinion shaft axis, and the indicator hand reverses direction. Zero the dial indicator and check the zero point again by slightly moving the cross-shaft fore and aft; then, rotate the companion flange from side-to-side.

8. With the indicator at zero, carefully retract the dial stem and rotate the flange 18° degrees. Rotate the cross-shaft 180 degrees on the flange bearing cups to position the exposed journal under the dial indicator adapter. Rock the cross-shaft fore and aft and the companion flange side-to-side to establish the point at which the indicator hand reverses direction. This will determine the driveshaft universal cross-shaft runout. Record this reading.




9. Repeat Steps 5 through 8 at least three times and average the indicator readings obtained.




10. To determine the total (combined) companion flange runout, use the combined runout guide. With an indicated 0.003-inch flange bearing cup runout and an indicated 0.004-inch universal cross-shaft runout, the combined companion flange runout will be 0.005-inch.

11. If the reading obtained in Step 10 exceeds specifications, re-position the companion flange 18° degrees on the pinion shaft and repeat Steps 1 through 11.

12. If the repeat readings still exceed specifications, re-position the flange an additional 9° degrees on the pinion shaft and check the runout (Steps 4 through 10).

13. If the runout is still excessive, replace the companion flange and check the runout. If necessary, rotate the new flange on the pinion shaft until an acceptable runout is obtained.

If excessive runout is still evident after replacement of the companion flange, replace the ring gear and pinion and repeat the above checks until the runout is within specifications.