Replacing the original two cylinder engine in a 70 John Deere with a 4 cylinder D-2 Cat engine, has certainly created many challenges. The axis of power for the Cat engine is in-line, whereas in the John Deere, it is crosswise. The transition of power was accomplished by building a transfer case. This case also serves as a structural component, joining the bell housing of the Cat to the main casting of the Deere. A front differential from a 3/4 ton Chev. provides the right angle drive. A large silent chain connects the transfer case to the J.D. crankshaft. The original crank was replaced by a new straight shaft. Probably, the most difficult machining, was milling a tapered spline on the new shaft. The J.D. clutch driving disk had to end= up in a precise fixed position, so the tapered spline had to be milled to a close tolerance. The original cam gear is keyed to the new shaft also, thus using the original tractor pressurized oil system for lubrication. All fabrication and machining was done at my farm shop.
The John Deere 70 had an aftermarket taper-lock flywheel, so I put a matching straight spline on the input side, and incorporated the taper-lock in the silent chain sprocket. The chain and one sprocket were obtained from salvage, the other sprocket was machined totally from scratch.
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The heart of the transition case is a extra big scrap yard find, piece of square tubing, with one inch wall thickness. Since the only way the differential would fit is corner to corner, The machining also came with it's own challenges.
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