Axle boots are plastic or rubber bellows that cover the joints of a drive shaft.
The drive shaft transmits the engine torque from the gearbox or differential to the wheels. Because the wheels move up and down during driving, the drive shaft is not rigid. Drive shafts have joints that compensate for the resulting angles and ensure that the shaft does not snap. These joints are protected by axle boots, which are also known simply as the bellows. They prevent dirt and moisture from getting in and are designed to ensure that lubrication of the joints is guaranteed.
Axle boots are wearing parts. Particularly those made of rubber become brittle sooner or later and then tear. Cracks often occur due to stresses during driving. If axle boots crack or are damaged, they must be replaced. Otherwise there is a risk of damage to the axle joints and even the drive shaft. Plastics or thermoplastic elastomers (TPE) are widely used for modern axle boots. This material is more stable and load resistant and less sensitive to temperature.
Axle boots must be replaced in a specialist workshop using the required special tools.
By having the axle boots checked regularly, drivers can detect wear at an early stage and thus prevent faults with the axle joints and the drive shaft.
If axle boots are faulty or worn, grease can escape and be ejected onto the brake disc, which can result in a significant reduction in braking power. A broken or blocked drive shaft can also be a serious safety risk.