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Early U-Joint Assembly Tool (1928-1939)

By Stephen Kassis

U-jointU-joint

Early passenger car & 1/2 ton u-joints are held together with two round plates bolted together around the pivot balls of the U-joint trunnion. When reassembling this type of U-joint, a special tool is available to assist in this procedure.

The plate at the front yoke has four fixed studs fixed into it. This plate must fit over the round pivot balls, locking them into the recesses of the plate. Holding this plate steady while assembling the U-joint is the main purpose of this tool.

Before assembly, it is a great opportunity to check the condition of the driveshaft bushing. This bushing sits inside the torque tube and his held in place by a dowel pin. If this bushing is bad it can cause vibration when driving. To check the driveshaft bushing, grab the splines of the propeller shaft within the torque tube. If you can move the shaft up and down without moving the outer tube, the bushing should be replaced. Both the bushing and seal should be replaced before assembling the U-joint. (See separate installation instructions that come with torque tube bushings.)

The first step in assembling the U-joint is to check the ball housing gaskets. These gaskets must be installed prior to assembling the U-joint. New gaskets are always recommended. If these gaskets are not fresh, leaks may occur. Prior to assembly of the U-joint, it is important to adjust the gaskets on the ball housing to achieve proper sealing. The U-joint gasket set consists of 4-5 adjusting shims, large collar gasket and small rear housing gasket. Install the metal collar without the collar gasket. Put in 4 or 5 adjusting shim gaskets (with four holes) and tighten down the collar onto the ball housing. Check that it is a tight fit but not binding. A good test is to hit the rear of the ball housing lightly with a rubber mallet. If the housing will not move, add a shim. If it is too loose, remove a shim.

On early vehicles, prior to 1933, the rear of the ball housing has a permanently fixed gasket at the rear. It is two metal washers with a cork gasket in between. To replace this gasket, dig out the old cork with a small screwdriver and blow out with compressed air. Lubricate a #327 neoprene O-ring with grease and push it in between the two washers. For later models, the ball housing has a screw-on flange which allows for easy gasket replacement. Once the gaskets are adjusted properly, install the collar gasket, slide the collar over the ball housing and push the assembly onto the torque tube. Be sure to hang the shim gaskets in place as they cannot be added after the U-joint is assembled.

Assure the balls are installed on the trunnion properly. Each ball has a flat side and a recessed side. The flat side should be faced outward on each stud. This will leave the recessed side facing inward. The orientation of these balls is important for proper lubrication of the trunnion. With the balls installed properly, seat the stud plate against the two balls of the front yoke and hold temporarily while installing the tool.

Slide the forks of the tool behind the stud plate. Center the tool at the end of one of the trunnion arms and tighten the thumb nut. This should bring the stud plate up snugly against the U-joint pivot balls. This will also position the four studs in the plate so they are facing outward. Install the outer ring onto the mating piece and assemble lock washers and nuts. Be sure the transmission is in gear so the U-joint will not turn. Snug down the nuts to hold the plate in place. Remove the installation tool and torque the four nuts to around 8 foot pounds. To tighten all nuts may require turning the U-joint. If this is necessary, put the transmission into neutral, loosen the thumb nut and rotate the assembly without removing the tool. Re-tighten the thumb nut and finish tightening the nuts.

Assemble the ball housing and collar assembly onto the back of the transmission and tighten the four bolts with lock washers.  The final step is to add about 1/2 pint of gear oil (same type as is required for the transmission) into the ball housing. On early transmissions, there is a fill plug at the top of the ball housing at the rear. If there is no fill plug, it will be necessary to remove the speedometer drive gear to fill the U-joint with gear oil. IMPORTANT: DO NOT use grease to lubricate this U-joint. This assembly requires gear oil and using grease will eventually cause driveshaft bushing failure.

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