Drive shafts require joints at either end to allow for angular change. Drive shafts turn at high speed. The Universal and Constant Velocity Joints allow drive to be transmitted through an angular change. This requires the shafts to be well balanced with minimal free movement. The objective of this procedure is to show you how to check drive shaft joints for wear.
Part 1. Preparation and safety
- Check drive shaft joints for wear.
Whenever you perform a task in the workshop you must use personal protective clothing and equipment that is appropriate for the task and which conforms to your local safety regulations and policies. Among other items, this may include:
- Work clothing - such as coveralls and steel-capped footwear
- Eye protection - such as safety glasses and face masks
- Ear protection - such as earmuffs and earplugs
- Hand protection - such as rubber gloves and barrier cream
- Respiratory equipment - such as face masks and valved respirators
If you are not certain what is appropriate or required, ask your supervisor.
- Never hold a shaft that is being driven by the engine.
- Make sure the vehicle is safely supported on a suitable vehicle hoist. The wheels need to be free to turn.
- Make sure that you understand and observe all legislative and personal safety procedures when carrying out the following tasks. If you are unsure of what these are, ask your supervisor.
Points to note
- Drive shafts require joints at either end to allow for angular change. The most common type of joint is referred to as a "Universal Joint", however the correct term for it is a "Hookes Joint". They can also be known as a "Cross and Yoke Joint" or a "Cardan Joint".
- Drive shafts can contain components referred to as "Constant Velocity Joints". These are in the form of a "Lobro Joint" or a "Double Cardan Joint".
- Drive shafts turn at high speed. The Universal and Constant Velocity Joints allow drive to be transmitted through an angular change. This requires the shafts to be well balanced with minimal free movement.
- A large amount of torque is transmitted through the shafts, so joint wear is normal.
- Constant Velocity Joints, mounted at the end of axles or half shafts, pass more torque than Universal Joints mounted in drive shafts; they also operate at greater angles. Although they are larger, they are still subject to wear. The indication of excessive wear is a clicking noise when the vehicle is driven with the wheels at full lock. The noise is caused by the drive balls being forced into, and out of the wear grooves. Severe cases are indicated by noise at lesser steering angles.
- Drive shafts pass less torque than axles but they turn at much higher speeds. A small amount of wear will cause an imbalance, which will lead to a vibration creating more wear.
- Any wear in a Hooke's Joint or a Constant Velocity Joint requires replacement of the entire joint.
Part 2: Step-by-step instruction
- Check driveshafts for looseness
On any rear wheel drive vehicles, including pick-ups and SUVs, inspect the drive shaft universal joints for signs of excess movement or rust. With the vehicle in a condition where the drive wheels can be turned,
- Rotate shaft & flange
rotate the shaft and flange in opposite directions to check for wear. There should be no movement in the joint. Any lateral movement, noise or signs of rust, should be reported to your supervisor. Repeat this for each universal joint. On the 4WD vehicles, repeat this procedure on the front drive shaft universals.
- Raise the vehicle and turn wheels by hand
With the vehicle driving wheels in a raised condition where they can be rotated, turn the steering wheel to maximum lock, and rotate the road wheel. You should not hear any abnormal noises such as clicking or grinding. If you hear a distinct clicking noise as the wheel rotates on full lock, it indicates that the balls and their housing inside the joint are excessively worn. Turn the wheel to the opposite lock and repeat the procedure for the other side.
- Check sealing boots and clamps
Check the condition of the sealing boots. Make sure there are no tears or splits, and that the retaining clamps are tight. A common practice to confirm that the joint needs replacing without stripping the joint, is to drive the vehicle in a tight circle in a safe place in one direction and then the other. If the noise increases and decreases in intensity in relation to the rotational speed, the joint needs replacing, and you should report your findings to your supervisor.