may be front, rear, or both depending on model CV joints transfer torque from the transmission to the drive wheels at a constant velocity in reference to the axle shaft. CV joint boots seal in a special grease that protects and lubricates the CV joint. The actual CV joint doesn’t need maintenance and can last a very long time provided the protective boot is not compromised. If you notice a CV joint boot is cracked or damaged, replace it immediately with a CV Joint Boot Kit, which contains all the parts you need to complete the job quickly and easily. If done as a preventative measure, you can keep from having to replace the CV joint.