Sprocket lock nut Sprocket lock washer Oil deflector Chain sprocket Main drive gear

6. Thrust washer

7. Roller bearings (44)

8. Main drive gear oil seal

9. Oil seal cork washer 10. Main drive gear spacer

11. Main drive gear spacer key

12. Bearing race retaining ring

13. Bearing race

14. Gear box

15. Main drive gear bushing

Figure following name of part indicates quantity necessary for one complete assembly.

Figure 4D-14. Main Drive Gear - Exploded View light side of case, slipping third gear (10), retaining washer (11), spring lock ring (12) and shifter clutch (13) off left end of mainshaft and out through shifter cover opening in case.

If bearing housing does not come out with bearing when mainshaft assembly is being removed, slide gear (8 or 8A) along mainshaft until edge of large gear is against bearing housing and drive out housing together with mainshaft. To avoid damage to case, make sure gear is positioned so it does not overlap housing.

Disassemble the mainshaft gear and ball bearing assembly only if inspection shows a need for replacing worn or damaged parts.

Clamp mainshaft in copper-faced vise jaws. Bend ear of lock washer (5) away from flat of nut (4) and remove nut and washer. Bearing (6) and gear (8) may then be removed with the All Purpose Claw Puller, Part No. 95635-46 or an arbor press. If using claw puller, insert center adapter, Part No. 95636-46, into end of shaft to prevent damage to shaft. Bearing and gear are removed separately.


Position gear box in vise and nail or bolt length of rear chain to bench. Engage chain on sprocket teeth to keep sprocket from turning.

Bend ear of lock washer away from flat of nut and remove sprocket lock nut (1) and washer (2). Nut has left hand thread. Lift oil deflector (3) and chain sprocket (4) off gear. Push main drive gear (5) into case and withdraw it from top. Thrust washer (6) usually comes out with gear. Remove the 44 roller bearings (7). Be sure all rollers are accounted for and wrap them in paper or cloth. If any of these rollers are lost or if rollers from another bearing become mixed with them, the entire set must be discarded and a new set fitted, even though the old rollers are in serviceable condition.

Do not remove main drive gear oil seal (8) or main drive gear spacer (10) unless inspection shows damage or wear. Complete instructions for removing oil seal and spacer may be found in Section 4D.


Clean all parts except gaskets (all gaskets should be replaced) with cleaning solvent and blow dry with compressed air.

Inspect all gears. If teeth are pitted, scored, cracked, chipped or if case hardening is worn through, replace with new gears.

Inspect all bushings, bearing races and shafts. If bent or worn, install new parts. If mainshaft ball bearing (6, Fig. 4D-13) is worn to point where play is obviously too great, install new bearing.

To install main drive gear bearing race (13, Fig. 4D-14), heat case to about 300 degrees and press out old race with arbor press after removing bearing race retaining ring (12). Reheat case and press in new race until flange is seated against case. Install new bearing race retaining ring.

Oil seal cork washer (9) and oil seal (8) should not be reinstalled if they have been removed. An oil leak will probably develop. Use new parts.

Carefully check shifter clutches (13, Fig. 4D-12 and 4D-13) and engaging dogs on gears. If they are rounded or battered appearing, they must be replaced.

Worn shifter clutch and gear dogs result from shifting abuses or from out-of-adjustment clutch that does not release fully. Damaged engaging dogs try to creep out of engagement under a steady load. This creeping action develops great side pressure that results in damage to shifting mechanism and all thrust points along shaft assemblies.

Check bearings (7, Fig. 4D-14 and 18, 22, Fig. 4D-12) for proper fit in races according to tolerances shown in "Transmission Specifications," Section 4A. Replacement rollers are available standard, .0004 in. and .0008 in. oversize.



Assuming that main drive gear oil seal (8), oil seal cork washer (9) and gear spacer (10) are assembled in case (replacing these parts must be done before gear box is disassembled or after it is repaired and assembled as described in Section 4A), install rollers (7) in bearing outer race (13), holding rollers in place with a light coat of grease.

Install main drive gear thrust washer (6) on main drive gear. Insert main drive gear (5) into gear box. Be sure rollers stay in place as gear is inserted.

Install main drive gear spacer key (11), registering longer section of key in any splineway on main drive gear and shorter section of key in slot in outer edge of main drive gear spacer.

Install sprocket (4) with flat side outward. Install oil deflector (3), lock washer ^2) and sprocket lock nut (1). Hold sprocket as outlined in disassembly procedure and tighten nut securely. Check main drive gear assembly end play. See "Transmission Specifications," Section 4A, for proper tolerances. Bend one ear of lock washer against flat of nut.


Assemble parts 4 through 8 to mainshaft before installing mainshaft in gear case. Position gear (8) on shaft splines. Press or fit ball bearing housing (7) over ball bearing (6) and press onto shaft. Assemble lock washer (5) and nut (4) to shaft and tighten securely. Bend over one ear of lock washer against flat of nut.

Insert mainshaft assembly into gear box far enough to install gear (10), thrust washer (11) lock ring (12) and shifter clutch (13) over shaft. Always install new lock rings and make sure they are properly seated in lock ring groove. One side of mainshaft shifter clutch is stamped "HIGH." Make sure this side faces main drive gear.

With a screwdriver or other suitable tool, work lock ring onto shaft splines. Use screwdriver wedged against shifter clutch to force lock ring into seat in shaft.

With a soft-metal hammer or brass drift, tap mainshaft assembly into case until flange on ball bearing housing is t'.ouldered against case. Install retaining plate (3), oil deflector (2) and four screws (1).

If working on three-speed transmission, install reverse idler gear (31, Fig. 4D-12) and shaft before installing retaining plate.


Before installing countershaft gear train to shaft and case, it is necessary to check bearing fit and shaft end play.

If countershaft mounting collars (32 and 33) were removed for replacement, press or drive old parts out and new parts in after gear case has been heated to approximately 300 degrees to expand case and facilitate pressing.

Install roller sets (18 and 22) in countershaft gear (25), holding them in place with a coat of grease. Be sure lock rings (20 and 24) and bearing retaining washers (19 and 23) are in place before installing bearings. Install bearing thrust washer (21) in its recess in left end of countershaft gear. Install countershaft temporarily to check bearing fit. See "Transmission Specifications," Section 4A, for tolerances.

Install countershaft gear in case holding end play adjusting washer (9) in place with daub of heavy grease. Install countershaft.

Check end play with feeler gauge between end play adjusting washer and end of countershaft gear. Consult transmission specifications for tolerances. Increase or decrease end play as necessary by fitting end play adjusting washer of required thickness. Washers are available in thicknesses of .074, .078, .082, .085, .090, .095 and .100 in. When correct gear end play has been established, remove countershaft and gear from case. Set aside adjusting washer until needed for assembly.

Install gear bushing (17), gear (16), thrust washer (15) and gear lock ring (14) on countershaft gear (25).

Install shifter clutch (13), thrust washer (12), gear bushing (11) and gear (10) on countershaft gear. Check to make sure all rollers are in place in gear.

Place end play adjusting washer (9) on end of countershaft gear, holding in position with daub of grease. Position assembly in case and insert countershaft (8) and lock plate (7). Straight edge of lock plate fits against edge of bearing retaining plate (3, Fig. 4D-13). Install lock washer (6) and nut (5). Tighten nut se curely and bend over one ear of lock washer against flat of nut.

Install gasket (4) and end cap (3) with washers (2) and screws (1). Install gasket (29), drive unit (28), washer (27) and screw (26).

Install shifter cover, starter clutch, starter cover and clutch as described in pertinent sections.

Assemble transmission to motorcycle and connect controls in reverse order of stripping procedure described in "Stripping Motorcycle for Transmission Repair," Section 4A.


A three forward speed and reverse transmission cannot be installed on a foot shift model motorcycle, and a three-speed transmission cannot be assembled in a four-speed gear case.

The disassembly, repair and assembly procedures for a three-speed and reverse transmission are the same as for a four-speed transmission except for the procedures described in operations to four-speed model and following differences:

Refer to Fig. 4D-12. In three-speed and reverse countershaft assembly, omit shifter clutch (13), lock ring (14), thrust washer (15) and gear bushing (17).

Substitute gear 10A for 10, 16A for 16, and 25A for 25.

Substitute 8A for 8 and 10A for

Refer to Fig. 4D-9. Substitute 8A for 8.

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