The Differences Between a U-joint and a CV Joint

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Tip from Dick:

A normal, simple "u-joint" has a single cross, and 4 cup style needle bearings. There are no other "moving" parts (forgetting that of course the whole shebang rotates with the driveshaft). In fact, if the shaft angles are perfectly aligned, and nothing ever moved laterally or vertically, you could eliminate the u-joint and drive the car with a shaft of metal, ALA mid 60's tempest "rope" drive. The length of a simple u-joint varies with the strength requirement and thus the size of the parts, of course, but typically, from the weld bead of the driveshaft yoke to the junction of the opposite yoke with the trans. or differential shaft is around 4 to 5 inches.

The constant velocity, or CV, joint ( this is the correct term, based on its function, which is to provide smooth motion regardless of adjacent shaft angles) has two complete normal u-joints as described above PLUS the centering yoke and bearing assembly. For more detailed information, take a look at section 16 of your shop manual for many if not all Chryslers of the 60's and 70's. The total length of the CV joint as applied to Imperials will be around 8 to 10 inches, thus very easy to identify as different from a normal u-joint.


A U-joint (U is for "Universal"), which is also called a "Cardan" joint after the guy who invented it, is a type of flexible coupling typically used on both ends of the driveshafts. Each U-joint consists of a four-legged center cross with needle bearing cups on the ends of each leg of the cross. The bearing cups on one pair of legs are mounted to the driveshaft. The other pair of cups are held in place by a pair of U-bolts attached to a yoke that mates to either the transmission or differential. The bearing cups allow the joint to swivel and bend as the driveshaft follows the motions of the differential and axle as the suspension bounces up and down.  These may need periodic lubrication.

A CV (for constant velocity) joint does essentially the same thing as a U-joint, only better. There are two basic types: "ball-and groove" CV joints and "tripod" CV joints.

Ball and groove CV joints, which are used as the outer joints on most front-wheel drive cars, consist of a cup-shaped outer housing, a center race and cage assembly. Machined into the outer housing and center race are six grooves that hold six steel balls. The balls are held in position by windows or slots cut into the cage assembly. The joint is designed so that when it bends, the balls are always positioned at the midway point inside the joint. This eliminates the cyclic variations in speed that a U-joint experiences when it operates at more than a few degrees off-center.

The tripod style of CV joint consists of a three-legged cross or trunnion with roller bearings on the end of each leg. The trunnion is attached to the driveshaft, and the roller bearings run in machined grooves or channels in an outer "tulip" housing. This type of joint is also designed to plunge in and out, and is used as the inner CV joint on most domestic front-wheel drive vehicles.

All CV joints are enclosed by a rubber or hard plastic boot. The boot keeps grease in and contaminants out. CV joints do not require periodic maintenance or greasing, and are engineered to last 100,000 miles or more.

All front-wheel drive cars have four CV joints: one inner joint and one outer joint on each of the vehicle's two driveshafts (which are also called "halfshafts").

This page last updated October 25, 2003.  Send us your feedback, and come join the Imperial Mailing List - Online Car Club