Which precision measurement tool should you use to measure excessive wear on U-joints?

To measure excessive wear on U-joints, you should use a Dial Indicator. Here are the steps:

1. Secure the U-joint in a vise or similar holding device.
2. Set up the dial indicator so that the plunger or rod is perpendicular to the surface of the U-joint that you want to measure.
3. Zero out the dial indicator.
4. Apply a force to the U-joint in the direction you want to measure. This could be done by hand or with a tool.
5. Read the measurement on the dial indicator. This will tell you how much the U-joint has moved, which indicates wear.
6. Compare this measurement to the manufacturer's specifications for the U-joint. If the measurement is outside of these specifications, the U-joint is excessively worn.