Contents: Cleaning ↓ Clutch housing, gearbox housing,…↓ Oil seals, sealing gaskets ↓ Shafts ↓ Gears ↓ Bearings ↓ Rods, forks ↓ Hubs, couplings, synchronizer…↓ Differential ↓ Gear selection and shifting…↓
Cleaning
Before inspection, gearbox parts are cleaned. Using a brush or scraper, remove all deposits and clean the holes and splines from possible contamination, then wash and blow with a stream of compressed air. It is especially necessary to blow out the bearings, directing the stream of compressed air so that rapid rotation of the rings does not occur.
Clutch housing, gearbox housing, cover
There should be no cracks or chips on the gearbox and clutch housings, and no wear or damage on the surface of the bearing holes. There should be no damage on the mating planes of the clutch and gearbox housings to prevent shaft misalignment and loss of sealing of the gaskets.
Check the condition of the rear cover to make sure that the breather is in good condition, not dirty, and the surface of the cover that contacts the gearbox housing is not damaged. Clean the magnet from particles of wear of parts. Minor damage to the surfaces is eliminated with sandpaper. Damaged or worn parts are replaced with new ones.
Oil seals, sealing gaskets
Check the condition of the working edges of the seals. No unevenness or significant wear is allowed on the edges. Formation of a cylindrical belt of more than 1 mm as a result of wear on the working edge is not allowed. Even if there is minor damage, the seal is replaced with a new one. It is recommended to replace the sealing gaskets with new ones.
Shafts
Check the condition of the teeth of the gears of the primary and secondary shafts. The teeth should not have chips, nicks or wear. There should be no scoring or wear on the shaft seating belts for the bearings. The splines and grooves of the shafts should not have dents, scoring or wear to ensure a backlash-free fit of the synchronizer hubs. If the specified damage is present, replace the shaft with a new one.
Gears
The gears must not have chipping, wear or nicks on the end face of the synchronizer ring. The contact patch between the gear teeth in engagement must extend over the entire working surface of the teeth; the specified surface of the teeth must not have wear. Check the gap in the engagement of the gear teeth with an indicator, having first installed the gearbox shafts in a special housing with windows for access to the gears. The installation gap should be 0.10 mm, the maximum gap 0.20 mm.
Bearings
Ball, roller and needle bearings must be in perfect condition. The radial clearance of ball and roller bearings must not exceed 0.05 mm. No damage is allowed on the surfaces of balls, needles and rollers, as well as on the raceways of the rings. Damaged bearings are replaced with new ones. Needles and separators of needle bearings must not have damage or signs of wear.
Rods, forks
Deformation of forks, rods and gear selection and shift levers is not allowed. The rods must slide freely in the crankcase holes and in the bushings. The condition of the springs and locking balls is checked. Parts that show signs of seizing or wear are replaced with new ones.
Hubs, couplings, synchronizer locking rings
Check that the hubs are not damaged, especially on the sliding surface of the couplings. Pay special attention to the condition of the ends of the coupling teeth. Excessive wear of the locking rings, damage or traces of seizure on the balls, springs and crackers are not allowed. Possible irregularities that prevent the free sliding of the couplings and locking rings are removed with a velvet file. Parts that are damaged and worn are replaced with new ones.
Differential
Check the condition of the surface of the satellite axle, half-axle gears, satellites and the mating spherical surface of the differential box. Check the condition of the bearing seat belts on the differential box.
In case of minor damage to the surfaces, the unevenness is removed with fine-grained sandpaper, and in case of significant damage, the parts are replaced with new ones.
Gear selection and shifting mechanisms
Check the condition of the forward and reverse gear selector lever, thrust bushing and washer, gear selector lever axles and locking brackets. Replace worn and damaged parts. Check the condition of the gear selector rod, the fastening and condition of the gear selector lever, the condition of the oil seal and protective cover. Replace worn and damaged parts. Check the fit of the gear shift lever in the ball joint. The lever must rotate freely in the support, without jamming and must not have free play. Deformation of the drive rod and damage to the protective cover are not allowed. A deformed rod is replaced or straightened.
The dimensions of the main mating parts and the limits of permissible wear during operation are given in Table 8.
