Making a Wood Bros. Differential Gear Out of a Free Pattern
The pinion placed on the differential and the casting machined with the spider gears, or beveled gears, back inside the windows on the spider of the differential. Notice the difference between the oil tube and the completed casting. Mike Murphy added 1/8-inch pipe, bent it to fit the contour of the casting and put a grease fitting in the end of the pipe.
Left: The damaged center body of the differential, or spider – notice the holes the beveled gear shaft sat in and how egg shaped they are.
Right, from top: The two large center bosses; notice they are made up of two layers of 1-by. The outline made with a copping saw to make the beveled gear window on the pattern. The small blocks of wood cut and glued in segments.
Left: A good view of how the inside radius turned out.
Below: The completed pattern along with the finished casting that came back from the foundry.
This is the differential gear ready to go on the engine. Mike also recessed grease fittings in the ends of the spider gear or beveled gear shafts. Sorry to all you guys that say keep it original, but they are hidden pretty well and Mike knows the grease will do a lot better job of lubrication.