Sachs 5 Speed Mainshafts

What's the Difference

by Alan Buehner

I recently received a phone call from a customer who was looking to transfer the inside components of his Sachs 5 speed engine case of which the outside, ignition side was broken to the inside of a newly purchased used Sachs 5 speed engine case. In trying to do the switching he discovered that bearing for the main shaft was a different size diameter and he called me to see I had a bearing to fit it. I carry both sizes of bearings in stock, however the inside diameters are also different. There are also 2 different size main shafts that correspond to these bearings.

The customer wound up keeping his old clutch side half and using the new/used ignition side half. Both cases were the “A” cases that used the larger diameter crank.

The purpose of this article to alert everyone that is involved with the Sachs engines that there is a difference with the Sachs “A” engines with regard to the main shafts and show you just what the differences are.

Photo “A” shows the two different 5 speed main shafts The top main shaft is for the early Sachs engines that use the 8mm selector rod and key (as shown in photo “B”. The lower main shaft uses the 10mm selector shaft and key. As you can see, from the side they look almost identical except if you compare them at the ends.

The bearing end the main shaft that uses the 8mm selector shaft measures 20mm O.D. The bearing end the main shaft that uses the 10mm selector shaft measures 25mm O.D. as shown in photo “C”.

Photo “D” shows the sprocket end of the main shafts The top main shaft has a 8mm I.D. And the bottom main shaft has a 10mm I.D.

Photo “E” shows the 2 bearings. The top bearing is a 16004 bearing, part number 0232-130-001, and measures 20mm I.D. X 42mm O.D. The bottom ball bearing is a 16005 bearing, part number 2732-006- 000, and measures 25mm I.D. X 47mm O.D.