UNIVERSAL JOINTS

PURPOSE Allows flexing of the driveshaft due to suspension movement. Allows flexing of the driveshaft due to suspension movement.

CONSTRUCTION A steel ‘X’ with each end precision machined. A steel ‘X’ with each end precision machined. Bearings caps with small needle bearings fit over each end. Bearings caps with small needle bearings fit over each end. Grooves for retaining rings are cut into each cap. Grooves for retaining rings are cut into each cap. A grease fitting is fitted to allow for regular lubriciation. A grease fitting is fitted to allow for regular lubriciation.

LOCATION One universal joint is attached to the driveshaft at each end. One universal joint is attached to the driveshaft at each end. The front u-joint is also attached to a slip yoke which fits into the tailstock of the transmission. The front u-joint is also attached to a slip yoke which fits into the tailstock of the transmission. Some heavy duty vehicles with a two-piece shaft have three u-joints. These vehicles will also have a hanger bearing which may require service at the same time. Some heavy duty vehicles with a two-piece shaft have three u-joints. These vehicles will also have a hanger bearing which may require service at the same time. Some older 4 wheel drive vehicles have a u-joint at each front wheel also. Some older 4 wheel drive vehicles have a u-joint at each front wheel also.

PROBLEMS Universal joints wear from high mileage and a lack of regular lubrication. Universal joints wear from high mileage and a lack of regular lubrication. Dry u-joints rust and seize, causing noises and vibration. Dry u-joints rust and seize, causing noises and vibration. Excessively worn u-joints can break, causing costly damage. Excessively worn u-joints can break, causing costly damage.

DIAGNOSIS A light squeaking noise that increases with vehicle speed. A light squeaking noise that increases with vehicle speed. Heavy clunking when shifting into drive or reverse. Heavy clunking when shifting into drive or reverse. Heavy vibration at highway speed. Heavy vibration at highway speed. Powdery rust coming from the bearing cap. Powdery rust coming from the bearing cap. Rock vehicle back & forth with transmission in park, observe u-joint for play. Rock vehicle back & forth with transmission in park, observe u-joint for play. Pry u-joint with a large pry bar and watch for visible movement. Pry u-joint with a large pry bar and watch for visible movement.

APPROXIMATE COST OF REPAIR Depending on vehicle design and load capability, u-joints are relatively cheap. Depending on vehicle design and load capability, u-joints are relatively cheap. Usually between $20 - $50 each, it is recommended to replace all u-joints at the same time. Usually between $20 - $50 each, it is recommended to replace all u-joints at the same time. 1-2 hours labour to diagnose and replace 2/3 u- joints. 1-2 hours labour to diagnose and replace 2/3 u- joints. Special skills and procedures are needed to replace a u-joint without damaging the drive shaft. Special skills and procedures are needed to replace a u-joint without damaging the drive shaft.