Closed Driveline Torque Tube
One of the most misunderstood parts on early Chevys is the closed driveline torque tube. Over the 30+ years I have sold parts for these vehicles, I have come across dozens of restorers and professional mechanics that do not understand the basics of adjusting & maintaining them.
Closed driveline manual transmission U-joints from 1929-1954 are designed to be lubricated by GEAR OIL only. Do not use grease! Most transmissions have a separate fill plug at the rear above the ball housing. This plug is to fill the ball housing after assembly. Some transmissions without fill plugs must be filled through the speedometer drive gear opening. YOU MUST MANUALLY FILL THE BALL HOUSING WITH GEAR OIL - DO NOT RELY ON THE GEAR OIL IN THE TRANSMISSION TO FILL THIS HOUSING. IT WILL BE TOO LITTLE TOO LATE!
Before installing a new U-joint, check the torque tube drive shaft bushing for wear. This bushing can be checked by grasping the drive shaft at the spline end and move it up and down within the tube. If there is ANY movement of the shaft within the outer tube, the bushing is worn out and should be replaced. A bad bushing will cause driveshaft vibration and can cause U-joint failure. New bushing and seal assemblies are available for most 1916-1954 passenger cars & 1/2 ton trucks.
Install a new U-joint gasket set (FS-125 or FS-125P) when you install a U-joint. After installing the U-joint, fill the ball housing with about 1/2 pint of 90W (1932 or earlier models use 600W) Fill through the top plug at the back of the transmission. FAILURE TO PROPERLY LUBRICATE THE U-JOINT CAN CAUSE PREMATURE FAILURE AND SERIOUS DAMAGE TO THE DRIVESHAFT BUSHINGS, U-JOINT AND TRANSMISSION HOUSING. Refer to the shop manual for proper adjustment of the U-joint shims when installing new gaskets.