We wash the outer part of the gearbox, prepare the keys for repairing the gearbox
Having installed the gearbox on the workbench, use a 10 mm wrench to unscrew the two bolts securing the locking plates of the differential bearing nuts and remove the plates.
Use a punch to mark the bearing bed and the corresponding cover so that the covers can be installed in their places during assembly.
Use a 17 mm wrench to loosen the cover mounting bolts bearings.
We take out the outer bearing rings and adjusting nuts from the differential housing.
If we do not change the bearings, then we mark the outer rings so as not to mix them up during installation, because the bearings have individually run in and it is not advisable to disassemble them.
We check for radial play in the axle gears.
We press off the inner bearing rings with a puller.
Using a 17 mm wrench, unscrew the eight bolts securing the driven gear to the differential housing and remove it.
Use a punch to knock out the satellite axle.
We turn the axle gears and take out the satellite gears
We take out the axle gears with adjusting washers, marking their position
We take out the drive gear and the deformed spacer sleeve from the crankcase.
When assembling the gearbox, we replace the sleeve with a new one.
Using a soft metal punch, knock the inner ring of the tapered bearing off the pinion shaft.
An adjusting ring is installed under the bearing, ensuring the correct relative position of the main gear gears.
Using a suitable tool, knock out the outer rings of the tapered bearings from the crankcase
Thoroughly wash the gearbox parts in kerosene and carefully inspect them.
If at least one tooth is damaged (chipping, waves, scores, scoring on the working surfaces), replace the gears with new ones.
The edges between the vertices and the working and the surfaces of the driven gear teeth must be sharp.
If the slightest nicks or roundings are visible, replace the main pair with a new one.
Minor damage to the satellite axle, the necks of the half-axle gears and their mounting holes is eliminated with fine sandpaper followed by polishing.
During assembly, replace the cuff, flange nut and spacer sleeve with new ones.
If the gearbox is to be assembled in the old crankcase, then the change in the thickness of the adjusting ring of the drive gear can be calculated as the difference in the deviations in the sizes of the old and new gears.
The deviation in size with a “+” or “–” sign in hundredths of a millimeter is engraved on the shaft of the drive gear.
For example, -12 is engraved on the old gear, and -12 on the new one 4.
The difference between the two adjustments is 4–(–12)=16.
This means that the new adjustment ring should be 0.16 mm thinner than the old one.
With the opposite ratio of adjustments (4 on the old one, and –12 on the new one), the ring should be 0.16 mm thicker than the old one.
For a more accurate determination of the thickness of the adjustment ring, we make a device from the old drive gear.
Weld on a plate 80 mm long and face it to a size of 50–0.02 mm relative to the plane under the bearing.
The factory number and the size deviation are engraved on the conical part of the shaft.
We grind the bearing seats (you can process them with fine sandpaper) to a sliding fit.
We press the outer rings of the front and rear bearings into the crankcase.
We install the inner ring of the rear bearing on the manufactured device and insert the device into the crankcase.
We install the inner ring of the front bearing, the flange of the drive gear and tighten the nut with a torque of 0.8–1.0 kgf.cm.
We set the crankcase to a horizontal position according to the level.
We put a round even rod (an extension from a set of socket heads) in the bed of the differential bearings and use a flat feeler gauge to determine the value the gap between it and the fixture plate.
The thickness of the adjusting ring is determined as the difference between the gap value and the deviation of the new gear size (taking into account the sign).
For example, the gap value is 2.8 mm, and the deviation of the gear size is -15. This means that it is necessary to install an adjusting ring with a thickness of 2.8–(–0.15)=2.95 mm.
Remove the device from the crankcase.
Install the adjusting ring of the required thickness on the drive pinion shaft and press on the inner bearing ring using a piece of pipe of the appropriate size.
Insert the shaft into the crankcase.
Install a new spacer sleeve, the inner ring of the front bearing, the cuff and the flange of the drive gears.
Gradually tighten the nut with a torque wrench to a torque of 12 kgf/cm
We determine the moment of rotation of the drive gear shaft.
To do this, we tightly wind a strong thread around the flange neck several times and attach a dynamometer to it.
The force at which the flange begins to rotate evenly should be 7.6–9.5 kgf (which corresponds to a torque of 16–20 kgf•cm) (for new bearings).
If the force is insufficient, we tighten the flange nut. In this case, the tightening torque should not exceed 26 kgf cm.
If the turning torque exceeds 20 kgf cm (9.5 kgf) when tightening the nut, disassemble the gearbox and replace the spacer sleeve.
We install the differential housing together with the bearings in the crankcase and tighten the bearing cap bolts.
If axial play was detected in the axle gears, then during assembly we install new, thicker support adjusting rings.
The axle gears should fit tightly into the differential housing, but turn by hand.
From a 2.5–3 mm thick steel sheet, we make a key for tightening the adjusting nuts.
We adjust the clearance in the main pair and preload the differential bearings simultaneously, in several stages: tighten the nut from the side of the driven gear until the clearance in the engagement is completely eliminated;
Use a caliper to measure the distance between the covers
- tighten the second nut until it stops and tighten it to 1–2 teeth of the nut.
The distance between the caps should increase by approximately 0.1 mm;
- by rotating the first nut, we set the required clearance in the engagement of 0.08–0.13 mm.
This is the minimum play that is noticeable with the fingers, accompanied by a slight knock of tooth on tooth;
- we control the constancy of the gap in the engagement by hand and gradually tighten both nuts until the distance between the caps increases by 0.2 mm.
This will ensure the necessary tension of the bearings.
Slowly turn the driven gear three times and simultaneously “feel” the play in the engagement of each pair of teeth.
If it is uniform in all gear positions, then we install the locking plates.
A decrease (increase) in play in any sector indicates deformation of the differential housing and the need to replace it or face it on a lathe.
There are two types of locking plates: with one or two tabs.
Depending on the position of the nut slot, we install one of them.