The universal joint, or Hookes joint, is used to carry drive from one shaft to another where the two shafts are not perfectly in line and particularly where they can move relative to each other. It is used in propellor shafts at both the transmission output and the differential input ends, in steering swivels on part-time four wheel drive vehicles, in some steering columns, and in PTO winch drive-shafts.

The joint consists of a cross or spider which carries needles roller bearings at the four extremities. The bearing cups are fitted into yokes, two on the input shaft and two on the output shaft. The arrangement allows drive to be taken through an angle, particularly where that angle can change as it does in a prop' shaft due to suspension movements.

The universal joint is not a constant velocity joint: If there is a non-zero angle of deflection between the input and output shafts and if the input shaft is driven at a constant rate then the output shaft will accelerate and decelerate twice per revolution. This effect can be negligible for small angles of deflection but it increases with the angle of deflection and can cause vibration.

If a harsh vibration at high speeds is keeping you off the interstate, check your U-joints for proper alignment. The rotational speed of a universal joint varies or cycles as it turns through 360 degrees. Since universal joints are almost always installed in pairs, they are normally "phased" so this difference is eliminated. being cancelled out by the two joints. (As one joint speeds the rotation up, the other slows it down so the rotational speed of the output is fairly constant.)

Many driveshafts come apart for easy assembly, usually a splined shaft is used to transmit power from one piece to the next. If the splined parts are connected without insuring that the U-joints are in phase, a tremendous vibration can result at highway speeds.

To check your U-joints, jack up your car and support it on jack stands. (Never crawl under a car supported only by a jack.) A visual check will tell you if your U-joints are lined up correctly. Simply compare each end of the driveshaft to see if the yokes on each end (the parts welded to the driveshaft tube itself) lie in the same plane. (In a Morgan you masy have to open the gear box cover access panel). If they do not line up, or are at right angles to each other, it is usually a simple matter to unbolt the driveshaft and re-orient the splines of the two pieces to bring the universal
joints into proper phasing.

CHECKING  YOUR TEMPERATURE GAUGE

You can check the calibration of the temp gauge by removing the sending unit from the block. (You might loose some coolant, so you might want to have a catch pan handy.)

Take a pan of oil and carefully heat it.  (I suggest maybe using a Pyrex (sp) measuring cup to hold the oil, and placing it in a microwave oven.)  You will also need a candy thermometer, these will usually read to over 300 deg F.  You will also probably have to use a clip lead and connect one end to the sending unit the other end to the block .. to establish a ground.

When the oil is hot, you can measure its temp with the candy gauge.  No take the hot oil and dip the sending unit it in.  Turn your ignition to ON (NOT START) so the gauges have power.  Then watch the temp gauge and the thermometer.  I'd suggest making a small mark on the gauge glass with nail polish at 180, 212, and then 220.

Now you KNOW what temp your eng. is really running at.

John T. Blair
It is suggested that a good cooking oil is used. It could help your marriage. Lorne M. Goldman
jblair@scn.spawar.navy.mil