Car drive shaft coupling

Joint disk / Hardy disk can replace the joint in the cardan shaft. The cardan shaft connects the gearbox to the rear axle. Therefore, it is necessary in the cars that have drive on the rear axle. Typically, joint disk/ Hardy disk is situated between the cardan shaft and the gearbox driven shaft. The disk is made of rubber or similar material and is surrounded by two metal pillows. Hardy disk was named after the inventor John Leslie Hardy.

In the cardan shaft can occur displacements. Without joint disk/ Hardy disk there would be a strong pressure on the material. In addition, the gearbox and the drive would be affected. The flexible connection provides the displacement alignment. In addition, the disk absorbs small shocks and vibrations. This makes it possible to install a smaller cardan shaft. This reduces the costs any durability and safety losses. In some vehicles joint disk is situated between steering box and steering wheel.

The joint disc / Hardy disc is usually vulcanized in metal liners. However, there are models where the disc has a free position between two support members. A popping noise when starting, changing loads or switching usually indicates that the joint disk is damaged. When you replace the disk, it is necessary to note cardan shaft's position on the steering box not to make a mistake when mounting. You can order many other spare car parts in our Internet store. Here you will find injection valves, rear muffler, flange, transmission bearing, or parking brake cable. With the help of our effective search function you will quickly find the car parts you need.

How to detect the propeller shaft coupling failure

The part examination should be performed every 50,000 - 70,000 km. Cracks, breaks, scuffs, chips, delamination, excessive softness or hardening of the material indicate that the part has failed. It should be dismantled for a more thorough diagnosis. Typically, small cracks become visible only when the coupling is under stress. So to detect them you have to create the conditions that simulate real operation, for instance, mount the coupling on a fastening bolt clamped in a vice and stretch а corresponding coupling section with the help of a screwdriver inserted into the adjacent hole. This procedure should be repeated for each hole in sequence on both sides.

You may identify that the propeller shaft coupling needs diagnostics by the following symptoms:

• vibration is felt in the passenger compartment, increasing during acceleration;
• abnormal sounds are heard from the propeller shaft area while driving;
• propeller shaft mountings are broken.

Causes of the propeller shaft coupling failures

The propeller shaft flexible coupling is exposed to significant loads. To prevent the need for frequent replacement, it is important to buy only high-quality components produced from durable and sufficiently hard rubber.

Premature rubber disruption is contributed by temperature changes, the impact of aggressive chemicals, dirt and moisture. If the car is stored outside or operates in regions where roads are treated with chemicals in cold seasons, the coupling may crack earlier than usual.

Sometimes the part failure is induced by excessive vibration of the propeller shaft caused, for instance, by its deformation, wear of the bearings and bushes, loosening of the securing bolts. Propeller shaft centering bushes that are in direct contact with the coupling are recommended to be replaced together with the coupling.

The risk of the part damage increases substantially if it is mounted lopsidedly, the fasteners are unevenly tightened or the securing bolts are of different length.

Replacement of the propeller shaft coupling

You can replace the part on your own. For this follow the procedure below:

1. Mount the car on a pit, a car ramp or a lift platform.
2. Mark the surface of the propeller shaft and the spline end so as not to mix up their relative positioning during reassembly.
3. Unscrew the propeller shaft fastening bolts and disassemble it, disengaging from the flange.
4. After removing the fasteners, disconnect the coupling with the propeller shaft flange from the gearbox flange.
5. Unscrew the nuts that fasten the coupling to the propeller shaft flange and dismantle the coupling.
6. Install the new part, basing on factory-made marks or on those you made before disassembling.
7. Remove the band from the coupling.
8. If necessary, replace the centering bushes. Heat the propeller shaft flange to facilitate pressing them out. To press in a new part, use a pilot pin of the appropriate diameter.
9. Assemble the unit by following the steps in the reverse order.