What Are CV Boots?

A Constant Velocity (CV) boot covers the CV joint, which joins to the CV axle of an automobile. It is found in all front-wheel drive vehicles and many four-wheel drive and rear-wheel drive autos as well. It is a rubber casing filled with grease that protects the joint from outside wear and tear and contains lubricant that reduces friction on the joint and prevents friction-related damage in the axle's function.

Purpose

  • The CV boots cover the CV joints in an automobile. There are four of them on two-wheel drive vehicles and eight on four-wheel drive vehicles. They protect the CV joints both from friction-related damage and from external wear. This keeps the axle and steering capabilities of the car functional. The importance of the CV assembly is that it enables torque to be transmitted at a constant speed from the driveshaft to the turning wheels, while accommodating the vertical movement of the suspension.

Location

  • On automobiles that have CV boots, one pair of boots is located on either side of the vehicle along the drive shaft. The outer CV boots cover the joint between the axle and the wheel. The inner boots cover the joint between the axles and the transmission.

Appearance and Materials

  • A CV boot is usually a black rubber casing. It has an accordion-like fold across its surface to allow for the flexing actions of the joint. The overall shape of the boot is conical with the narrow side attached to the axle.

Warnings

  • While it is possible to continue to drive a vehicle with a damaged CV boot, it is not advisable. The more damaged the CV boot, the more the potential damage to the CV joint. A damaged CV joint ceases to transfer power to the wheels, which means the car is stuck where it's parked until the CV joint is replaced. Replacing the CV boot as soon as it demonstrates risk is a good idea because it's far less expensive than replacing the joint.