The cardan shaft is a thin-walled steel pipe, to which a splined tip is welded on one side, and a universal joint fork on the other. A sliding fork of the second hinge is put on the splined tip. The spline joint is sealed with an oil seal pressed by a clip, and a steel plug is pressed into the hole in the sliding fork on the side of the cardan joint. Both hinges are connected to flanges, one of which (sliding fork side) the shaft is attached to the flange of the transfer case, and the other (from the side of the welded fork) - to the gearbox flange. The cardan shaft assembly with flanges is dynamically balanced on special stands; imbalance is balanced by welding balancing plates to the shaft tube. When disconnecting the cardan shaft parts, note (paint or core) their relative position in order to put them in their places during assembly. Driveshaft needs to be rebalanced (or replace) in case of loss of balancing plates, deformation (first it is ruled), replacement of driveline parts (sliding fork, flange, cross with bearings). However, if, when replacing the cross, it was not necessary to select new retaining rings (new and old are the same size), then, as a rule, you can do without balancing. Imbalance of the driveline leads to noticeable vibrations at high speeds (above 60–80 km/h). A strong imbalance can cause destruction of the driveline and neighboring units.
The cardan joint consists of two forks interconnected by a cross. The cross has four spikes on which bearing housings with needles are put on (thin rollers). To protect against dirt, the bearing is sealed with an oil seal. Since 1988, the design of the hinges has been changed. The diameter of the spikes of the cross and bearings has been increased, and the latter have become stamped (used to be chiseled). Accordingly, the size of the forks and the holes in them has changed. Therefore, the individual parts of the cardan transmission of the new and old models are not interchangeable, but the shafts can be replaced as an assembly. In addition, the design of the stuffing box has been changed: one more working edge has been added, which made it possible to seal the bearing both in the radial and in the end direction. To reduce friction, a plastic washer is installed between the bearing housing and the end of the cross spike; high temperature does not occur at the contact point and the lubricant does not «welded». On the surface of the washer facing the spike of the cross, grooves are made from the center to the periphery for supplying lubricant from the cavity of the spike to the bearing needles. Lubricators are installed in the hinges and in the sliding fork to replenish the lubricant. For lubrication of hinges, Fiol-2U or grease No. 158 is used, for spline connections - Fiol-2U or Fiol-1.
In connection with the change in the design of the hinge, the procedure for its dismantling has changed (see Dismantling the universal joint) and selection of retaining rings. Retaining rings are available in eight sizes, different colors depending on the thickness: 1.45 mm - unpainted, 1.48 mm - yellow, 1.52 mm - brown, 1.56 mm - blue, 1.60 mm - black, and also 1.40 mm and 1.67 mm blank (thickness is controlled by measurement). When replacing the hinge, it is recommended to note the position of the retaining rings and install them in their original places.
After pressing the bearing (force not higher than 1500 kgf) the rings should fit snugly into the gap between the end of the fork groove and the bottom of the bearing. If the old rings do not enter the gap or do not fit tightly, we select new ones as described above (if rings of smaller thickness are needed, you can carefully grind the old ones). After installing the rings, we hit the hinge forks with a hammer with a plastic striker (or conventional through a wooden spacer), so that the bearing housings are firmly pressed against the circlips (check if the rings are tight), and an axial clearance of 0.01–0.04 mm appeared in the bearings. A correctly assembled bearing should have no appreciable play (the gap is very small and, in addition, the bearing housing is preloaded with an oil seal) and at the same time should rotate easily and without jamming.