Truing And Sizing Pinion Shaft Bearings Race

Before fitting new pinion shaft bearings, lap bearing race in crankcase to true and remove traces of wear at sides of roller paths. A smooth velvety finish should result. A race that is worn beyond limits of oversize bearing rollers must be replaced. See "Engine Specifications," Section 3A, for shaft fit in roller bearing.

To remove worn bearing race, remove two bearing bushing screws (15, Fig. 3E-20) from inside of right case and press out bearing race. Heat cases to 275° - 300°F. Heating expands case and makes it possible to remove bearing race using less force. Press worn race out and new race in. New race must be lapped slightly to true and align with left case bearing, and to attain a size compatible with roller sizes available.

Lap bearing race by inserting guide sleeve (1, Fig. 3E-28), Part No. 96728-56, from inside of case, through complete Timken bearing assembly on sprocket side of crankcase. Turn nut finger tight on sleeve. See "Assembling Crankcase," to install Timken bearing. This pilot will line up lapping arbor shaft through both bearing races so that an accurately lapped pinion shaft bearing race bore is obtained.

Temporarily assemble right and left cases with stud (9), bolts (3) and bolts (2, Fig. 3E-19). Securely tighten bolts to assure perfect alignment between left and right cases.

Insert crankcase main bearing lap (2, Fig. 3E-28) through pinion shaft bearing race and into guide sleeve in opposite race as shown in Fig. 3E-29.

Tighten arbor expansion collars using a length of 5/32 in. rod as spanner wrench until arbor begins to drag. Do not adjust arbor loose in bushing or bushing will "bell," a condition where hole is larger at ends than it is in the center.

Withdraw arbor far enough to coat lightly with fine lapping compound. Do not apply a heavy coat. Reposition lap in bushing and turn handle at moderate hand speed. Work lap back and forth in bushing as it is revolved to avoid grooving and tapering.

Figure 3E-29. Lapping Pinion Shaft Bearing Race

1. Screw 4. Outer race spacer and

2. Driver oil seal sleeve

3. Bearing sleeve

Figure 3E-30. Sprocket Shaft Timken Bearing Assembling Tool

At frequent intervals, remove lap from crankcase, wash and inspect bushing. Lapping is completed when entire bushing surface has a dull, satin finish rather than a glossy, smooth appearance. If necessary, flush off lap in cleaning solvent, air dry and apply fresh, light coat of fine lapping compound.

0 0

Post a comment