On front wheel and all wheel drive cars, the axle shafts are what connect the transmission with the wheels, driving the vehicle along.

This is a view of a front, outer drive axle joint boot or "CV" boot (stands for Constant Velocity) that has torn open. The greasy mass inside is the actual joint itself. The exposed grease quickly slings out under centrifugal force as the axle rotates while driving and the joint subsequently becomes contaminated with sand, dirt, rocks and water, rapidly wearing the joint components. Excessive wear may necessitate replacement of the entire axle shaft as an assembly… a much more expensive proposition than replacement of the boot itself.

Regular inspections at Motor Works will prevent this and lower your overall transportation costs!