Transmission Reassembly

NOTE: For Disassembled View of M-46 Transaxle and Components, see illustration Fig 1 .

Fig 1: Exploded View of M46 4-Speed Transmission Assembly

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Use drift to install intermediate shaft bearings. Use correct type bearings. Use drift to press input shaft bearing on input shaft. Install lock ring. DO NOT install spacer ring on bearing at this time.
NOTE: Intermediate shaft small end bearing is different for diesel applications.
Determine intermediate shaft preload. Place intermediate shaft in housing and use drift to install bearing races. Install clutch housing with gasket and tighten bolts. Turn transmission vertically so clutch housing is down. Use drift to tap rear race in position so that clearance is eliminated and shaft turns in a slightly sluggish manner.
Using a depth gauge, measure distance to outer race from rear surface of housing. Add measured distance to gasket thickness of .010" (.25 mm) plus preload of .001-.003" (.03-.08 mm). Total measurement is shim size required, select shim within this range and set aside for reassembly. Shims are available in the following thicknesses: .002" (.05 mm), .004" (.10 mm), .006" (.15 mm), .014" (.35 mm), .020" (.50 mm), .027" (.70 mm) and .039" (1.0 mm).
Remove clutch housing and gasket, then remove intermediate shaft. See DISASSEMBLY procedures . Install reverse gear shifter and lock ring. Install reverse gear and shaft. Shaft end should be at least .002" (.05 mm) below housing face.
Adjust clearance between reverse gear and shift fork to give .004-.040" (.10-1.0 mm) clearance. Adjust by tapping shift fork pivot pin in or out with a punch. Place intermediate shaft in bottom of housing, then position mainshaft in housing. With positioning lock ring fitted to bearing, fit thrust washer and bearing on mainshaft. See Fig 2 .

Fig 2: Adjusting Clearance Between Reverse Gear and Shift Fork
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Ensure that gears DO NOT interfere with each other and use press tool to press mainshaft bearing into position. If bearing does not align correctly, use spacer between tool spindle and housing front end. Press in until positioning ring is flush with housing face. See Fig 3 .

Fig 3: Installing Mainshaft Bearing
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Install lock ring on mainshaft bearing and insert key in mainshaft keyway. Install oil pump eccentric and lock ring.
Grease and install input shaft roller bearings, then position 4th gear synchronizer ring in synchronizer hub. Push input shaft into position on mainshaft. Lift intermediate shaft so that bearings are correctly positioned in housing.
Pull out input shaft so that spacer ring can be installed on bearing, then push shaft in so ring is against housing. Install outer bearing races for intermediate shaft bearings.
On aluminum housing models, use a depth gauge to measure distance from front of input bearing to surface of housing, then measure distance from clutch housing surface to bottom of bearing seat. See Fig 4 .

Fig 4: Measuring Surface-To-Bearing Seat Depth
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Add .010" (.25 mm) to clutch housing distance, then subtract distance of input bearing extension above housing. Choose shims to give .0004-.008" (.01-.20 mm) end play. Shims are available in the following thicknesses: .024" (.60 mm), .029" (.75 mm), .035" (.90 mm) and .039" (1.0 mm).
Attach clutch housing with shims, clutch fork including spacer and release bearing. Turn transmission to vertical position with housing DOWN. Tap intermediate bearing race in with drift (5180) until clearance is gone and slight drag is felt on shaft when rotated.
On cast iron housing models, determine shim thickness requirement for intermediate shaft to give .001-.004" (.025-.10 mm) axial clearance. Measure distance from rear housing surface to intermediate shaft outer race and add gasket thickness of .010" (.25 mm). Subtract axial clearance of .001-.004" (.025-.10 mm) to determine shim thickness. Shims are available in the following thicknesses: .002" (.05 mm), .004" (.10 mm), .006" (.15 mm), .014" (.35 mm), .020" (.50 mm), .027" (.70 mm) and .039" (1.0 mm).
Measure distance from mainshaft bearing to housing rear surface, and distance from rear cover surface to bottom of rear bearing seat. Allow for gasket thickness of .010" (.25 mm) and select mainshaft shim thickness to give .0004-.008" (.01-.20 mm) axial clearance. Shims are available in the following thicknesses: .024" (.60 mm), .029" (.75 mm), .035" (.90 mm) and .039" (1.0 mm). See Fig 5 .

Fig 5: Measuring Rear Cover Surface To Bearing Seat
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Install shift forks and gear selector rail with shift boss forward. Position gasket and shim pack for intermediate shaft on transmission housing. Use grease to keep mainshaft shim pack in place and install intermediate housing. Install 2 outer (lower) bolts finger tight. Install gearshift rod and sleeve on joint. See Fig 6 .

Fig 6: Installing Shift Forks & Shifter
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Install gearshift carrier. Note proper sequence of installation, bolt, washer, spacer, washer. Tighten rear cover bolts. Install 2 inner (lower) intermediate housing bolts. Tighten 4 lower bolts (2 inner and 2 outer).
Install overdrive unit. Install lock pin for shifter and glide washers for selector plate assembly. Install selector plate assembly and return spring. Install gearshift lever without lock screw and lock ring to check operation. Hold selector plate down with palm of hand and check gearshift operation. Correct as necessary, then remove gearshift lever. See Fig 7 .

Fig 7: Checking Gearshift Operation
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Install detent ball and spring, then install top cover with NEW gasket. Install overdrive switch, back-up light switch and wires at overdrive solenoid. Lower transmission rear and fill with transmission fluid. Install fill plug.