Contents: Cleaning ↓ Crankcase and covers ↓ Seals ↓ Shafts ↓ Gears ↓ Bearings ↓ Rods and forks ↓ Hubs, clutches and synchronizer…↓
Cleaning
Before inspecting the gearbox parts, clean them thoroughly. Use a brush or scraper to remove any deposits and clean the bores and splines of any possible contaminants, then rinse to remove and dissolve any oil residue.
Blow the parts with a stream of compressed air and wipe them carefully. Blow the bearings especially carefully, directing the stream of compressed air so that the rings do not rotate quickly.
Crankcase and covers
There should be no cracks in the crankcase, and no wear or damage on the surface of the bearing bores.
The mating surfaces with the clutch housing, rear and lower covers must be free of damage to prevent oil leakage. Smooth out minor damage with a file. If the parts are too damaged or worn, replace them with new ones.
Check the condition of the front cover and make sure that the input shaft does not touch it when rotating. If misalignment of the shaft and cover is detected, replace the damaged parts. Check whether the oil drain hole in the cover is clogged (shown by the arrow in fig. 3-15). Clean the drain plug.
Seals
Check the seals and make sure there is no damage, unacceptable wear or unevenness on the working edges. The wear of the working edges of the seals in width is allowed to be no more than 1 mm. If even a minor defect is detected, replace the seals with new ones.
Shafts
The working surfaces and splines of the secondary shaft must not be damaged or subject to excessive wear. The rolling surfaces of the needles at the front end of the shaft must not have any roughness or scoring.
Check the condition of the rolling surface of the needles in the bore of the primary shaft.
Inspect the intermediate shaft for chipping or excessive tooth wear.
The surface of the reverse gear pinion axle must be completely smooth, without any signs of seizing. The installation clearance between the axle and the intermediate reverse gear bushing is 0.056-0.09 mm, the maximum permissible clearance is 0.15 mm. Check the clearance by measuring the axle diameter and the pinion bushing hole. The axle diameter of new parts is 19.079-19.094 mm, and the inner diameter of the pressed bushing is 20.05-20.07 mm.
Remove minor surface irregularities with fine sandpaper. In case of major damage and deformation, replace the shaft with a new one.
Gears
There should be no damage or excessive wear of the teeth on the gears. Pay special attention to the condition of the ends of the teeth on the synchronizer rings.
The contact patch of the gear teeth engagement must be located over the entire surface, which must be smooth and without signs of wear. Check the clearance in the engagement between the gear teeth, the installation value of which must be 0.10 mm; wear limit - gap -0.20 mm.
The mounting clearance between the bushings and the gears of the 1st and 5th gears and between the secondary shaft and the gears of the 2nd and 3rd gears should be 0.05-0.10 mm; wear limit gap - 0.15 mm.
If wear exceeds permissible limits, replace the gears with new ones.
Bearings
Ball or roller bearings must be in perfect condition. Their radial clearance must not exceed 0.05 mm.
Pressing the inner ring to the outer ring with your fingers, rotate one of them in both directions, the rolling should be smooth. No damage is allowed on the surface of the balls or rollers and the raceways of the rings. Replace damaged bearings with new ones. When replacing the front bearing of the primary shaft, use the ejector A.40006 (fig. 2-11); in this case, the flywheel does not need to be removed.
Rods and forks
Deformation of the gear shift forks is not allowed. The rods must slide freely without significant clearance in the crankcase holes.
Check the condition of the rod locking crackers, springs and locking balls. Replace parts that show signs of seizing or wear with new ones.
Hubs, clutches and synchronizer locking rings
Check for signs of seizing on the coupling hubs, especially on their sliding surfaces. Pay particular attention to the condition of the coupling tooth ends.
Excessive wear of the surface of the locking rings is not allowed. They must be replaced if their end is resting against the synchronizer clutch. Any possible irregularities that prevent free sliding should be removed with a velvet file. Replace parts that are worn beyond the permissible limits with new ones.