Rivergate has had the occasion to see several Five Speed Datsun Transmissions that had been used with adapter plates built elsewhere. Some of these adapter plates were attempts to copy our plates and some were former manufacturers of conversion kits.
Our opportunity to see these transmissions was due to the owners bringing or shipping them to us after they had failed. Each one of them failed due to the same problem – failure of the adapter plate to align the transmission so that the center of rotation of the crankshaft was precisely aligned with the center of rotation of the transmission shaft. This causes the engine crankshaft bearings and the transmission bearings to put pressure on one another thru the pilot bearing. The transmission bearings almost always give up first due to unfavorable leverage.
The input shaft alignment in the front of the transmission in carried by the input shaft bearing (ball type) and by a set of needle bearings inside the back of the input shaft into which the bearing surface at the front of the output shaft is inserted. A failure resulting from misalignment generally kills both these bearings. The ball bearing on the input shaft can be replaced easily. But failure of the needle bearing between the input and output shaft ruins the bearing surface on both these shafts. Neither of these shafts are available from Nissan, so a transmission with this failure is expensive junk!
We wish to point out that we have never seen this failure due to misalignment on the adapter kit built by Paul Aspeirsson at Morris Motors. Our impression is that he builds good stuff.
Vesa Silegren, the Finnish born, Swedish trained engineer that did the CAD that drives the CNC machining that makes our adapter plates insures this doesn’t happen with our kits. He used a $40,000 measuring devise to design and check our adapters. Vesa seems to think of one thousandths of an inch as being a big thing.