General instructions for inspecting the parts
The dismantling of the transfer box was examined in the article — Dismantling the transfer box.
Before inspection, thoroughly clean all transfer box parts with a brush and scraper, then wash them. Blow the parts with a jet of compressed air.
Wash and blow the bearings especially thoroughly, avoiding their rapid rotation from the compressed air jet so as not to damage them.
Checking the condition of the parts
Crankcase and covers
The crankcase and covers must not have cracks; on the surface of the bores for the bearings, wear or damage (dents, chipping) is not permitted.
Damage to the mating surfaces of the crankcase with the covers can cause misalignment of the shafts and oil leakage.
Clean minor damage with a file.
In case of significant damage or wear, replace the parts with new ones.
Oil seals
Check their condition thoroughly.
If even minor damage is found, replace the seals with new ones.
The wear width of the working edge of the seal must not exceed 1 mm.
Shafts
Damage is not permitted on the working surfaces, the threaded part and the splines of the shafts.
Check the runout of the primary shaft and the drive shafts of the front and rear axles by mounting them on prisms and turning them by hand.
The runout of the end face of the thrust bands for the bearings must be no more than 0.01 mm.
When checking the intermediate shaft, pay attention to the condition of the gear block and the speedometer drive pinion.
Chipping or excessive wear of the teeth is not permitted. Replace defective parts.
Gears
When inspecting the gears, check the condition of the teeth and the seating surfaces.
Chipping of the teeth and their excessive wear are not permitted.
There must be no scores or wear on the seating surfaces of the gears that would cause excessive clearance.
Check the clearance in the gear mesh; the assembly clearance must be 0.10 mm, the maximum permissible — 0.20 mm.
The assembly clearance between the low-range gear and the bush, as well as between the primary shaft and the high-range gear, must be 0.05–0.10 mm, the maximum permissible — 0.15 mm.
In case of wear exceeding the permissible limits, replace the gears with new ones.
Bearings
Ball and roller bearings must not have damage on the races of the rings, on the cages, rollers or balls, nor cracks and chips on the rings.
The radial clearance of the bearings must not exceed 0.05 mm.
When rotated, a clean, dry bearing must not knock.
The movement must be even, without jamming.
Replace damaged bearings.
Rods and forks
Deformation of the forks and jamming of the rods in the crankcase holes are not permitted.
Replace the detent parts with new ones if traces of jamming are found.
Also replace the detent springs if they lose their elasticity.
The length of the spring under a load of 99.15–114.85 N (10.2–11.8 kgf) must be 19 mm, in the free state — 23.3 mm.
Hubs and sleeves
Check for traces of jamming on the hub of the gear engagement sleeve and, especially, on the sliding surfaces of the sleeves, as well as on the splines of the differential housing.
Clean scores and burrs with a file.
Pay special attention to the condition of the ends of the sleeve teeth; if they are destroyed or crushed, which prevents its movement when shifting, replace the sleeve.
Differential
Check the condition of the surface of the pinion shaft and the holes in the differential housing; in case of minor damage, polish the surfaces with fine-grained abrasive paper, and in case of significant damage — replace the parts with new ones.
Check the condition of the surface of the journals of the axle drive gears and their seating holes in the differential housings, as well as the condition of the supporting surfaces on the adjusting washers and the mating end surfaces on the housings and axle drive gears.
Eliminate the detected damage with fine-grained abrasive paper or a smooth file; replace significantly damaged or worn parts.
With the spring washer 14 removed (see figure), make sure there is no radial movement of the circlips 8 in the grooves of the shaft 13. If play is found, replace the circlips.
Testing the transfer box
Test the assembled transfer box on a stand for noise, assembly quality and absence of oil leakage.
Carry out the check successively in high and low range at the following primary shaft speed in both directions:
- I mode — 100–200 min⁻¹;
- II mode — 2000–2500 min⁻¹;
- III mode — 3500–4000 min⁻¹.
In the second mode, carry out the check without load and under load with variable torque, and in modes I and III — without load.
Check the operation of the differential in the first mode, alternately braking the drive shafts of the front and rear axles until they come to a complete stop.
Carry out gear shifting and differential locking with the transfer box shafts stationary.
The following are not permitted in the transfer box: jamming of both the gears and the differential lock, knocking or uneven noise of the gears and oil leakage.
Assembling the transfer box
We assemble the transfer box in the reverse order according to the article — Dismantling the transfer box.
When assembling the inter-axle differential, we align the marks on its housings.
We install the spring washer on the pinion shaft on the side of the blind hole at the end of the shaft.
Using pipe sections or socket spanners of suitable size, we press on the inner race of the front bearing of the intermediate shaft.
We press on the bearing of the front axle drive shaft (the pipe must rest on the inner race).
We press on the differential bearings.
In the same way, we press on the bearing of the rear axle drive shaft, the rear bearing of the intermediate shaft, the front and rear bearings of the primary shaft.
We install the primary and intermediate shafts into the transfer box crankcase simultaneously.
We apply a thin layer of silicone sealant to all sealing gaskets.
Having tightened the nuts of the rear bearings of the primary and intermediate shafts to the prescribed torque, we lock the nuts by pressing their collars into the grooves of the shaft shanks.
After assembly, we fill with oil.
Tightening torques for the fasteners of the transfer box parts
Part — Thread — Torque, N·m (kgf·m)
- Nut fastening the suspension bracket on the cushion axis — M10×1.25 — 26.5–32.3 (2.7–3.3);
- Nut fastening the suspension bracket to the body — M8 — 15.0–18.6 (1.53–1.90);
- Nut fastening the covers of the transfer box crankcase, the front axle drive crankcase, the speedometer drive housing, the control lever bracket — M8 — 14.7–24.5 (1.5–2.5);
- Differential lock switch — M16×1.5 — 28.4–45.0 (2.9–4.6);
- Bolt fastening the forks to the gear engagement rods — M6 — 11.8–18.6 (1.2–1.9);
- Bolt fastening the forks to the differential lock rod — M12×1.25 — 11.7–18.6 (1.2–1.9);
- Bolt fastening the driven gear — M10×1.25 — 66.6–82.3 (6.8–8.4);
- Nut fastening the rear bearing of the primary shaft and the rear bearing of the intermediate shaft — M18×1.5 — 96.0–117.6 (9.8–12.0);
- Nut fastening the propeller shaft flange to the primary shaft and to the front and rear axle drive shafts — M16×1.5 — 96.0–117.6 (9.8–12.0).
Materials and tools used
- Brush and scraper — for cleaning the parts of dirt.
- Compressed air jet — for blowing and drying the parts, especially the bearings.
- File (smooth) — for cleaning minor damage and burrs.
- Fine-grained abrasive paper — for polishing surfaces in case of minor damage.
- Prisms — for checking the runout of the shafts.
- Pipe sections or socket spanners — for pressing on bearings and races.
- Silicone sealant — for the sealing gaskets.
- Engine or transmission oil — for filling after assembly.
- Test stand — for testing the transfer box for noise and tightness.