M46, M47 & M47-II
NOTE:
The M47 (1985 version) has the 5th gear synchronizer located on the mainshaft and M47-II (1986 version) has the 5th gear synchronizer located on the intermediate shaft. See Figure and Figure.
- Install transmission in work stand and drain lubricant. Disconnect wires at overdrive solenoid, back-up light switch and overdrive switch (if necessary). Remove gear shift assembly. Remove transmission top cover and gasket.
- Lift out interlock spring and ball. Remove selector plate assembly, return spring and glide washers. See Fig 1. On M46 transmissions, remove overdrive retaining nuts from intermediate flange and remove overdrive. Remove gearshift selector rod lock pins and remove gear shift assembly. Unbolt intermediate housing from transmission and remove with gasket and shims.
- On all transmissions, remove clutch fork and release bearing. Save spacer washer for reassembly. Remove clutch housing, gasket and shims. On M47 and M47-II transmissions, remove gear shift assembly. Lock transmission into gear. Remove drive flange retaining nut and drive flange, using Puller (5304). Remove rear cover and seal from cover.
- On M47 transmissions only, remove bolt, washer and shims from intermediate shaft. Using Puller (988-7693-0), remove rear housing and gasket. Remove thrust washer and roller bearing with washer. Drive out 3 lock pins. Remove selector shaft(s), shift forks and selector shaft seal. Pull 5th gear from intermediate shaft using appropriate puller on bolt head. Remove 5th gear and synchronizer ring. Remove long bolt from intermediate shaft.
- On M47-II transmissions only, remove bolt, washer and shims from intermediate shaft. Replace bolt in intermediate shaft. Using Puller (988-7693-0), remove rear housing and gasket. Remove thrust washer and roller bearing with washer. Drive out 3 lock pins. Remove selector shaft(s), shift forks and selector shaft seal. Pull 5th gear from intermediate shaft using appropriate puller on bolt head. Remove 5th gear and synchronizer ring.
- To disassemble synchronizer assembly, clamp a box-end wrench in a vise. Using Shaft (5986) and torque wrench, loosen retaining nut. If retaining nut comes loose at a torque lower than 22 ft. lbs. (30 N.m), replace retaining nut. Any further disassembly should be done only if parts are being replaced. To remove intermediate shaft bearing, insert Puller (5261) between rollers, pull out spindle and expand puller. Remove bearing holder from rear face.
- On M46 and M47-II transmissions, drive out lock pin(s). Remove selector shaft(s), shift forks and selector shaft seal. Remove spring and disassemble 5th gear synchronizer. On M47-II transmissions, remove spring and disassembly 5th gear synchronizer. Remove 2 retaining screws and remove hub using Puller (5262). Save adjusting shims.
- On M46 transmissions with cast iron housings, remove intermediate shaft rear bearing race by tapping shaft back until race is free, then tap forward until front race can be removed. On aluminum housings, tap shaft back and forth enough to install Puller (5177) and remove races. On all M46 transmissions, remove lock ring and pull off overdrive oil pump eccentric.
- On all transmissions, place Adapter (2985) between input shaft and front synchronizer ring. Using Puller (5058), Adapters (5148 or 5248) and Puller Bolt (5147), pull off mainshaft bearing. On M46 transmissions, remove thrust washer, leaving Adapter (2985) in place. See Fig 2.
- On all transmissions, pull out input shaft and synchronizer ring. If bearing remains tight in its bore, ensure front of countershaft is contacting lower portion of housing, leave Adapter (2985) in place and tap mainshaft with a soft mallet.
- Turn transmission and lift out mainshaft. Turn transmission back and remove countershaft. It may be necessary to tap out rear bearing. Remove reverse gear and shaft. Remove selector for reverse gear.