Drive Shaft Restoration
by John Ironside
(This article was originally published in the December, 2012 issue of the Spark Coil.)
I determined that a number of parts were defective while disassembling the drive shaft. One decision that needs to be made prior to ordering parts is which type of pinion bearing will be used. The original style requires a bearing sleeve pressed onto the drive shaft and some tedious milling of the universal bushing to eliminate end play of the shaft. Furthermore, the experts question the quality of remanufactured pinion bearings since they are made without lubrication grooves. The modern bearing assembly incorporates a ball bearing and tapered roller bearing in a special spool that looks like the original on the outside. These bearings do not require a sleeve on the drive shaft, do not require thrust bearings, and since the assembly is locked onto the shaft, there is no need to mill the universal bushing for a tight fit. Although it costs about 45% more than the original equipment, I selected the modern pinion bearing assembly for this project.
So then this was my parts order for rebuilding the drive shaft:
o Universal Joint
o U-Joint Pin
o Front Drive Shaft Bushing (brass)
o Modern Pinion Bearing Assembly
o Pinion Gear – 11 tooth
o Pinion Key
o Pinion Castle Nut
The cost of the parts order was about $250.
Below is a photo of the new parts for the pinion end of the drive shaft. The assembly instructions that came with the modern pinion bearing assembly were straightforward. First, slide the locking collar on the shaft, followed by the spool containing the ball bearing, and then the tapered roller bearing. After inserting the pinion key in the keyway, slide the pinion gear on the shaft and thread on the pinion nut. The nut is tightened to 70 ft. lbs. of torque before being secured with a cotter pin through the shaft and nut. With the pinion gear in place, the bearing assembly is pushed tight to the gear, followed by the locking collar that is snugged up to provide a slight bearing drag.
I could now begin work on the universal end of the drive shaft, so I inserted the drive shaft into the housing and through the front bushing that had been pressed into place. I secured the pinion bearing spool to the housing with temporary bolts. Just to test the alignment, I gave the pinion gear a spin and heard a rubbing sound.
Finally, I determined that the locking collar set screw was rubbing on the inside of the housing, so I called the bearing assembly manufacturer for advice. After some discussion, checking Ford fabrication drawings, and making caliper measurements, we verified that the housing I.D. on my car was smaller than spec and that extra metal thickness was provided in this area. So using a small grinding wheel to reestablish the specified inside diameter of the housing, the pinion spool was reattached and the rubbing noise was eliminated.
There are two threaded plugs on the universal ball housing that must be removed to access the U-joint pin. After grease lubricating the universal joint, I inserted the universal over the end of the drive shaft. The pin hole is then aligned with the plug holes, the pin is inserted, and the ends of the pin are peened to lock the universal in place. But how do you peen the pin inside the housing? I found the answer in a string on the Model T Forum. Prior to inserting the pin, peen over one end. Insert the pin through the plug hole in the housing into position and thread a bolt down on top of the peened end. The bolt that has the right thread to fit the plug hole is the one holding the fan support arm to the engine block. Using a drift pin through the other plug hole, peen over the end of the U-joint pin. Screw the plugs back in the holes and the drive shaft is reassembled.
In the next issue of the Spark Coil I will share with you my experience disassembling the rear axle.