The u-joint is a very durable unit – far more so than the modern Hardy Spicer counterparts. Its durability stems from the fact that it is well-sealed with no bearings to seize or otherwise deteriorate.The working parts are entirely covered by a steel cover that bolts to the drive flange sandwiching a paper gasket. Two smaller metal collars sit inside and outside the cover to keep grease in and dirt out of the unit as it rotates. The larger of these two (with the Hardy Spicer inscription) sits outside the main cover and has a rubber gasket to help seal the unit.
The interior working parts look like a typical U-joint consisting of two hinges and a yoke. However, rather than needle or roller bearings, the ends of the yoke rotate in four hardened steel bushings. Two of the bushings are held into place with wire clips slipped into the matching retaining grooves on the bushings and housing. Two are not.
Maintenance of the unit is limited to greasing in accordance with the schedule in the owners manual. However, after seventy years or so, it is wise to disassemble them, examine for wear and give them a thorough cleaning.
The front unit on my Le Mans was packed with hardened dirt and grease which restricted mobility at least when turned by hand. The rear unit had very little grease at all. Both units had some play from wear, but not enough for me to consider replacing them. This undoubtedly would require machining new bushings, as they are not readily available over the counter.
Once cleaned, the units were re-packed with grease and reassembled.
