The cardan shaft consists of an intermediate cardan shaft, an intermediate bearing, a rear cardan shaft and three cardan joints.
The intermediate propeller shaft is made of thin-walled steel tube.
A shank with external splines is welded to the rear end of the intermediate shaft, and a fork is welded to the front end, to which a sliding front fork with an internal spline hole and a dirt deflector is attached through the cardan joint.
The front fork (shank) is inserted into the extension of the rear case of the transmission and engages with the splines of the output shaft.
When the rear suspension is in operation, the driveline is longitudinally displaced.
In this case, the shank, moving along the splines of the gearbox output shaft, compensates for these shifts.
The splined joint is lubricated with oil in the gearbox housing.
The intermediate support is a rubber corrugated element; a closed ball bearing is vulcanized to it from the inside, and a bracket from the outside.
The rubber layer prevents the transmission of vibrations to the body and allows the driveline to move along the longitudinal axis of the vehicle. The intermediate support bracket is bolted to the frame cross member.
The support bearing does not require maintenance throughout its entire service life.
The rear propeller shaft is made of a thin-walled tube, to the ends of which the forks are welded.
A splined yoke of the middle joint is attached to the front of the shaft through the cardan joint.
It is put on the rear splined part of the intermediate shaft after the intermediate support.
It is secured from displacement along the slots with a bolt with a lock washer. A flange with a centering collar is connected to the other part of the rear propeller shaft through the hinge crosspiece.
It is attached to the final drive pinion flange with four bolts.
The universal joint consists of forks and a crosspiece with four sealed needle bearings. Each of them has 20 rollers (needles) with a diameter of 2 mm.
The needles are made with high precision, matched to the given bearing assembly with a cross and are not interchangeable for different bearings.
Therefore, it is unacceptable to replace only the crosspiece or bearings, the entire set is replaced as a complete set, even if at least one bearing is damaged.
A grease nipple is screwed into the crosspiece. From it, the oil, pumped by a grease gun, flows through the internal channels to the bearings.
Oil retention inside the bearings is ensured by a spring-loaded rubber sleeve. When the universal joint is “injected”, the spring stretches and the excess oil flows out.
Needle bearings are pressed into the coaxial holes of the forks and are fixed in them with snap rings.
Cardan joints of all GAZ vehicles are traditionally lubricated with transmission oil. This is not very convenient, you have to often inject the connection.
Fill the bearings with # 158 grease, and you can forget about their existence for a long time.
When, during the repair of the cardan transmission, you find that the wear of the crosspiece is not great, and it will still serve, turn it 180˚ around one of the axes of the cleats and assemble the hinge in this position.
The spikes will start working on the unworn side and the resource of the knot will almost double.
Cardan transmission specifications
Maximum permissible radial play of the cross-piece bearings - 0.1 mm
Maximum permissible runout of the propeller shaft tube - 0.6 mm
Runout of the landing collar of the drive gear flange 0.15 mm
Runout of the output shaft of the gearbox 0.15 mm
Possible malfunctions of the cardan transmission. Their causes and methods of elimination
- Cause of malfunction
Vibration of the cardan transmission when driving:
- Deformation of the propeller shaft tube
Replace the propeller shaft tube or repair it with mandatory dynamic balancing
- Loosening the fastening of the rear propeller shaft to the rear axle
Tighten threaded connections
- Separation of the balancing plate from the shaft tube
Replace the propeller shaft tube or repair it with mandatory dynamic balancing
- Increased backlash of the crosspiece in the cardan joint bearings
Replace the bearings and crosspieces of the universal joint
- Increased runout of the landing collar of the drive pinion flange of the rear axle reducer
- Increased runout of the sliding fork installed in the gearbox
Eliminate the causes of the output shaft runout.
Replace transmission extension due to worn out steel-babbit bushings
- Defective bearing of the intermediate support
- Loosen the fastening of the intermediate support to the bracket or the bracket to the bottom of the body
Tighten threaded connections
Knocks when there is a sharp change in the amount of torque transmitted by the cardan transmission to the drive wheels (start of movement, transition to engine braking, gear shifting):
- Increased backlash in spline joints, as well as wear of bearings and crosspieces of cardan forks
Replace defective parts and assemblies
Malfunctions revealed during external examination:
- Oil leaks from the hinges due to damage to the cuffs
- Rotation of the cap with the cuff relative to the needle bearing cup (loss of a fixed fit and violation of the hinge tightness)
Replace the cross-piece with bearings, balance the cardan transmission.
- Rotation of the needle bearing cup in the bore of the hinge yoke
Replace worn parts, balance driveline
- When lubricating the hinge after 40,000 km of run, oil does not appear from under all the seals
Remove the cardan gear, disassemble the hinge, clean the channels of the crosspiece, close the bracelet springs in a ring and put them on the cuffs.
After assembling the joint, dynamically balance the propeller shaft
Inspection, check and lubrication of the driveline
First of all, inspect the driveshafts and forks - cracks, dents or other deformations are unacceptable.
The polished surface of the sliding fork must be free from wear and tear.
The splines of the sliding fork, the output shaft of the gearbox, and the rear hinge must be free of corrosion and signs of wear.
Inspect the support - rubber peeling from reinforcement, cracks and breaks are not allowed here.
The support bearing should rotate easily, without jamming and backlash.
On the removed cardan gear, you can assess the condition of the hinges without disassembling them.
Rock each joint in a different plane. There should be no noticeable backlash along the spike axis and no seizure.
If necessary, you can measure the radial clearance in the bearings of the crosses with an indicator.
To do this, grip one of the hinge forks in a vice on the cross-piece bearings.
Pressing the indicator leg against the free tab of the other fork, swing it around the propeller shaft axis.
Backlash of more than 0.1 mm is unacceptable. It indicates wear of the hinge and the need to replace the bearings and crosspiece.
If the holes in the forks themselves are worn out, the propeller shaft assembly must be replaced.
Having cleaned the grease nipple from the dirt, we inject the gear oil with a syringe into all the hinges.
In this case, its excess must come out from under the cups of all four bearings.
If the oil does not come out somewhere, then the hinge needs to be sorted out - the lubricating channel is clogged, the oiler valve or a spring has jumped off one of the cuffs.
Removing the cardan transmission
If the movement of the car was not accompanied by vibrations caused by the cardan transmission, then during the subsequent assembly, the pre-existing position relative to the gearbox and rear axle should be maintained.
To do this, turn on any gear in the box.
We mark with a chisel or a file the position of the front fork (dirt deflector) of the universal joint relative to the gearbox extension
We mark with a chisel or a file the position of the rear propeller drive flange relative to the rear axle flange.
Using the "13" wrench, unscrew the fastening nuts of the intermediate support, holding the bolt with the "12" wrench.
Using the keys "14" and "17" we unscrew the bolts securing the cardan transmission to the flange of the driving gear of the main drive.
By sliding the cardan drive back, remove the sliding fork shank from the extension of the rear gearbox housing and remove the cardan drive.
To prevent dust from entering the gearbox and oil leakage from it, plug the hole in the crankcase with a clean rag
We install the cardan transmission in reverse order, aligning the marks made.
We tighten the bolts of the propeller drive flange to the main drive pinion flange to a torque of 30-36 Nm.
Nuts of the bolts securing the intermediate support of the universal joint to the frame cross member 12-18 Nm.
Dismantling the cardan transmission and replacing the crosspieces
Since the cardan transmission is balanced at the factory, each time it is disassembled and reassembled, it is necessary to maintain the original relative position of the shafts.
Otherwise, noticeable vibration may occur when the vehicle is moving.
So that, when assembling, the splines of the intermediate shaft shank and the splined fork take the same position, we make marks with paint or a chisel on the intermediate shaft pipe
We make marks with paint or a chisel on the spline fork of the middle hinge
Use a screwdriver to bend the protrusion of the lock washer located inside the slotted fork
Having inserted a knob or a screwdriver into the plug, hold the hinge and unscrew the bolt three turns
We take out the U-shaped plate with pliers
Using a copper hammer or through a spacer, knock the fork off the slots of the intermediate shaft
We unscrew the bolt with a lock washer
Striking the intermediate shaft with a splined shank on a wooden lining, knock down the intermediate support
We take out the protective rings from the intermediate support
Before assembling the cardan gear, we put the Litol-24 grease into the grooves of the protective ring from the side facing the cardan shaft, and insert the ring.
We cover the splines of the intermediate shaft with the SHRUS-4 grease.
Using a mandrel made of a pipe (with a diameter approximately equal to the diameter of the intermediate bearing inner ring), press the support onto the intermediate shaft splines until it stops.
We put grease on the other side of the bearing and put on the second protective ring.
Install the O-ring into the groove of the rear propeller shaft fork.
We wrap the bolt with a lock washer put on it into the end of the shaft, after having lubricated the threaded hole with a few drops of sealant
Applying a sealant belt 10 mm wide on the lead-in part of the front shaft splines, put on the fork, aligning the previously applied marks
We insert the U-shaped plate under the lock washer so that the protrusion on the plate goes into the groove of the fork slot, and the tendril on the lock washer - into the cutout of the plate.
We wrap and tighten the bolt. We stop the bolt by bending the protrusion of the lock washer to its edge.
The tightening torque of the slotted fork mounting bolt is 50-56 Nm.
Dismantling the universal joint
Having washed the hinge parts with kerosene, we mark their mutual position.
Prying off with a screwdriver, carefully remove the bearing retaining rings.
It is more convenient to disassemble the hinge with a special puller.
If it is absent, we press out the bearing in a vice, for this we select a thrust ring and a mandrel from pipe sections or rings of old bearings.
We clamp the hinge in a vice so that the mandrel is located on the side of the oiler and press out the bearings.
Having removed the bearings assembled with cuffs from the crosspiece, remove the fork.
Similarly, we press out the second pair of bearings (the cuffs should remain in the bearing housings) and take out the crosspiece.
If a new hinge is installed, we wash its parts from conservation grease.
We wash each bearing separately so as not to mix the needles. There should be chamfers on the ends of the cuffs; they can be made with a small file.
After drying the washed parts, we put on the cuffs on the spikes of the cross so that the springs face the dirt deflectors.
Pour some oil into the bearing cups and put them on the crosspiece.
Now we remove three of them together with the cuffs, and leave the fourth (from the side of the oiler).
Further assembly of the hinge does not differ from assembling the hinge with used parts.
We put the free spike of the crosspiece, opposite the oiler, into the eye of the fork, and then the opposite spike with the bearing and the retaining ring put on it - into the opposite eye
We put on the bearing on the free spike by inserting it into the hole of the fork ear
After making sure that both bearings are directed into the fork holes, we clamp the hinge in a vice, placing a thrust ring between the vice jaw and the fork eye
Press in the bearing on the side of the oiler until the lock washer touches the fork eye.
We put the second locking ring on the opposite bearing.
We assemble both halves of the hinge in the same way, but do not forget to restore the mutual position of the forks using the marks made before disassembly.
When assembling the rest of the hinges, install the crosses so that the grease fittings of all hinges are in the same plane and on one side of the hinge.
Tool for disassembling universal joints
Disassembling any cardan joints will be easier and more convenient if you use the device shown in the figure.
The distance between the base plates is selected depending on the dimensions of the hinge.