I fancied a V twin engine for the hopper and I bough a small block 750cc Moto Guzzi engine without knowing if it could be mated to a 2CV gearbox. The layout of the Guzzi engine and gearbox is very similar to the 2CV with the flywheel being proud of the engine rear face and the starter motor mounted on the gearbox side of the join. A few back of an envelope calculations indicated that it would be relatively easy to make an adaptor plate. After I had sketched out an un-dimensioned layout for the parts required I found pictures of Claus Gaertner's adaptor which was basically the same as mine.
The engine and gearbox holes etc were measured on a 3 axis machine to 0.001mm. These measurements were used to program the CNC milling machine. The 15mm aluminium adaptor plate took two passes because the program wouldn't fit into the memory and was split. All the holes, countersinking etc were done by the CNC machine. Holes were tapped by hand. The only mistake was forgetting a pocket for the end of the starter motor shaft which was done by freehand milling.
The gearbox input shaft has the 'knob' removed and there's about 2 to 3 mm clearance between the this shaft end and the boss on the crankshaft of the Moto Guzzi. By chance the boss on the two engine crankshafts; 2CV and Moto Guzzi are the same but I couldn't make any use of this!
There are no modifications to the flywheel.
The pictures below are of the flywheel and carrier. The two part flywheel carrier is made of mild steel bolted together with high tensile M8 bolts using two roll pins to register the parts. There no roll pin or dowel locating the carrier on the Moto Guzzi crankshaft. The original clutch assembly just bolts onto the crankshaft with six M8 bolts and some fancy locking washers. I got them from Wurth, they ae called sicherungsscheibe form S article number 0493 8. The 2CV flywheel bolts onto the outer adaptor plate with high tensile M8 bolts and a roll pin for registration. The oilite pilot bearing and the oil seal have not yet been fitted.
Observant people might notice two M6 tapped holes which are for jacking screws to separate the two parts enough to get leverage to dismantle it. No roll pins were in place when the photos were taken.
David Tocher; Chassis #189
Since this article was written Alan Walker has successfully installed a small block Moto Guzzi into his car, see ePAG33 for a progress report and a fully dimensioned drawing. ePAG34 has details of how Alan made the required parts and, more importantly, how it performs on the road.
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