Reply To: U Joint problems

[Gregory Long]

Thank you Richard, your message will hopefully save some important parts on our Pierce Arrows from inadequate lubrication.

The early u-joints did not have roller bearings. They were plain smooth steel pins that ran in either steel or maybe brass bores. The gap between the pin and it’s bore was hopefully kept lubricated with grease.

The chore of cleaning and lubricatng these large and messy U-joints was often neglected.. It’s something that should be done on the teen’s cars every 500 miles or so.

The reason for the frequent service is that the smooth pin in a smooth bore with side-forces will constantly push the grease out of the gap between the parts. With modern U-joints the smooth pin runs in a roller bearing. The round pin is in contact with 10 or more rollers, but this is a thin line-contact, the remaining area around the rollers and between the pin and the rollers is full of grease. This trapped grease constantly re-plentishes the lubrication in the bearing-to-pin contacts.

I believe that 1931 or 1932 is the first year for a roller-bearing to be used in a Pierce-Arrow U-joint. I am positive that the cars of the teen’s and twenties had plain-bearing u-joints.

The cars of the 20’s had their u-joint enclosed in a curved cup, that had a spring-loaded, felt-sealed cap. The u-joint was lubricated with a ‘special Compound’ lubricant as specified by Pierce Arrow’s maintenance chart. This Special Compound was a sort of liquid grease. it would flow. it is the same as used in the steering gear boxes. The lubricant would flow and re-fill places it had been forced from during operation. Regular chassis grease will not ‘flow’. i does not re-fill areas that it had been forced out of.

In the enclosed U-joints of the ’20’s cars, I use a lubricant like used for the early transmissions and steering boxes. It does tend to ‘flow’ out of the U-joints and make a stripe on the underside of the floor-boards. The enclosure and felt-seals are not perfect at keeping the lubricant inside. BUT using pure chassis grease is dangerous, since it might allow a part of the joint to run without lubrication.

The early U-joints are not available as replacement parts. They have to be machined and rebuilt. This is a costly process. So frequent and liberal lubrication is important.

Greg Long