Dismantling the Mainshaft Remove the 1st gear, baulk ring and needle bearing, and remove the 3rd / 4th hub assembly and baulk ring. Remove the 1st gear bearing track by lightly tapping the inner part of the 1st / 2nd hub assembly. Remove the hub and baulk ring. Using a thin punch or similar tool depress the plunger which locates the 3rd gear thrust washer, rotate the washer until the splines align and the washer can be removed. Remove the 3rd gear, needle bearing, plunger and spring. Using two thin tools depress the two plungers simultaneously through the holes in the cone of the 2nd gear and rotate the thrust washer until the splines align then remove the thrust washer. Remove the 2nd gear, needle bearing, plunger and spring.

Reassembling the Mainshaft Check all parts are cleaned and worn parts replaced. Fit the needle bearing onto the 2nd gear bearing track, slide the spring into the hole fitting a plunger into each side. Slide the second gear over the plungers, you may need to depress them slightly, and onto the bearing, refit the thrust washer depressing the plungers so the thrust washer will slide hard against the gear, rotate the washer until both plungers fall into place. Fit the needle bearing onto the 3rd gear bearing track, slide the spring into the hole and refit the plunger, slide the 3rd gear over the plunger, again you may need to depress it slightly, and onto the bearing, refit the thrust washer, depress the plunger so the thrust washer will slide hard against the gear, rotate the washer until the plunger falls into place. Refit a baulk ring against the 2nd gear cone, slide the 1st / 2nd hub onto the mainshaft, using a suitable tool tap the 1st gear bearing sleeve into position and fit the 1st gear needle bearing, fit a baulk ring and slide the 1st gear into place. Refit a baulk ring onto the 3rd gear cone and refit the 3rd / 4th hub assembly.

Reassembling Gearbox All parts must be clean and worn parts replaced. Slide the selector finger inside the spool then refit this assembly back into the gear box. Refit the bellcranks (61) back onto the top hat bush in the same order as dismantled, slide this assembly back onto the pin in the base of the gearbox and fit the washer and a new locking nut. Slide the 5th / rev selector rod (26) into the bracket (27) and slide this through the 1st motion bearing bore in the case and align holes in the bottom of the case with the holes in the bracket. From the under-side of the gearbox refit the two dowels (90), washers (JK202) and bolts (JK317). The washers and dowels must have sealant around them to prevent leaking and the bolt threads a small amount of loctite. Hold the 3rd / 4th selector rod into position and slide the selector rod through the clutch end of the gearbox case and into the fork. Now hold 1st / 2nd selector fork in position and slide the rod through it and into the other side of the case, align hole in the 3rd / 4th fork and fit a roll pin.

6) Refit the mainshaft assembly. From the speedo end slide a mainshaft ball bearing onto the end of the mainshaft and using a piece of tube or similar tap the bearing inside the case. Using a depth micrometer compare the difference between the depth of the bearing and the depth of the retainer and fit shims of the same size to the nearest .001”. Refit the retainer (116), tab washers and bolts, fold the tab washer back. From the clutch end tap the mainshaft so as to return it back to its correct running position. Refit the 1st motion shaft, needle bearing, baulk ring and circlip.  7) Refit the reverse idler thrust washer (42) and the screw (JK303) that holds it in place with loctite, before doing the screw up tight, refit the shaft (140) to check it lines up, then tighten the screw, remove the shaft and refit the other thrust washer (43), align the hole on the back with the pin (84) in the bracket (41), idler gear (20) and needle bearing (56), slide the shaft(140) through all the parts and fit a new circlip (141) onto the end of the shaft. 8) Refit the laygear (02) , thrust washers and oil pick up pipe and check the end float in the laygear. Slide the layshaft (03) through the case from the speedo end and into the laygear and out the clutch end of the case. Fit the bearing sleeve (151) onto the end of the layshaft . 9) Slide the final drive pinion onto the mainshaft, then the reverse gear, bearing , bearing track and baulk ring. Refit the 5th / rev fork (25) and hub assembly (132) together, sliding them both on the mainshaft and selector rod until the hole on the fork lines up with the hole in the selector rod. Refit the locating bolt (94), nut (JK102) and a new star washer (96). Refit the splined sleeve inside the hub and screw the mainshaft nut (LH) back onto the mainshaft, select two gears, as mentioned in the dismantling procedure and torque the nut up. Remove the layshaft. Slide the over selector stop (93), if fitted, onto the selector rod and a baulk ring into the 5th / rev. Hub. Refit the ball bearing onto the 5th gear with a new circlip, and refit this assembly into the endplate with an internal circlip. With a new gasket (46) refit the endplate (16) assembly with the five bolts, use sealant on both sides of the gasket to prevent leakage. 10) Fit the thrust bearing (85). This bearing is made up of three pieces, the ball race and the two thrust washers. The holes in the thrust washers are different, the larger one must go against the case and the smaller on against the spacer (08). Refit the spacer (08) and slide the laygear (40) into the gap. Hold the gear in position whilst sliding the layshaft assembly, remembering spring washer (2213), through the end plate, laygear (40), laygear (02) and case again, you will need to tap the layshaft bearing gently the last couple of inches ,you may damage the circlip on the end of the layshaft if you hit the bearing to hard. Fit an internal circlip (60) inside the endplate double check both circlips (53 and 60) are fitted and located correctly in their relevant grooves then fit a new bung (68). 11) With the sleeve (151) still fitted, refit a new k-nut (JK133) 12) Refit both the speedo wheel and pinion with new gaskets, and refit the radiator adapter plate with a new tapered locking washer. 13) Place the gearbox on its side with the differential opening upper most, run a bead of sealant around the sealing face of the gearbox. Place the differential into position and refit the differential cover. Refit the two short and two long bolts with new tab washers and refit the three smaller screws, don’t over tighten these screws, the differential must be able to move from side to side. Gentle tap the differential from the speedo end of the gearbox as far as it will go until the differential makes contact with the case . Refit the detent sleeve, ball, spring and O-ring, fit the side plate and gasket on the detent side of the differential, as it tightens down it should push the differential back towards the speedo side of the gearbox. With a depth micrometer measure the depth of the bearing on the speedo side of the differential and also measure the lip on the other side plate, the shims required will be this difference plus .007” for the thickness of the gasket and .004” to correctly pre-load the bearings. Fit these shims and side plate, tighten down all the bolts on the differential cover and side plates, knock back the tab washers.