Sachs Pistons and Rings

What's the Difference

by Alan Buehner

The purpose of the article is to take the confusion out of identifying the different type of pistons and style of rings used in the Sachs engines.

When the Sachs engines were assembled and shipped from the Sachs factory, there were two type of cylinders provided, cast and aluminum.

From 1968 to approximately 1970, cast iron cylinders were installed. The pistons used in these came with an "L" ring that was positioned below the top edge of the piston (see photo A). They also came with a square ring a few millimeters below that. Both of these rings were a dull finish that look like they are aluminum.

Photo A - showing a Mahle piston for cast iron cylinder. Arrow shows gap between top edge of the piston and the top edge of the ring.
Photo B - showing Mahle piston, left and Wiseco piston, right (note locating pin placements).

Aluminum cylinders were used on engines starting in 1970. The pistons used in these were Mahle pistons that came with a thin, shiny steel "L" ring on the top edge of the pistons and a shiny steel bottom ring below it. These are what are shown in the parts lists. There were aftermarket pistons made by Mahle and Wiseco (not shown in the parts lists) that use a black carbon "L" and bottom ring. These rings look alike but there is a difference in the bottom rings. The ends of the rings are cut differently to fit the locating pin inserted into the pistons (see photos B and E). It is important when ordering rings to know these differences because on the Mahle pistons, the black carbon rings are thicker and will not fit the pistons designed for the shiny steel rings.

Photo C - showing different "L" rings. L to R - Mahle cast iron, Mahle shiny steel, Mahle black carbon, and Wisco black carbon.
Photo D - showing different bottom rings. L to R - Mahle cast iron, Mahle shiny steel, Mahle black carbon, and Wisco black carbon.
Photo E - showing different cuts on bottom rings.
Top - Mahle black carbon, ends cover pin
Bottom - Wisco black carbon, ends surround pin

The Mahle pistons can be identified by the pistons size (in millimeters) stamped on the top (see photo F). The Wiseco pistons are stamped with an arrow (pointing to the exhaust) and sizes stamped with oversize in thousanths (.020, .040, .060 etc). Mahle pistons can also be identified by the name "Mahle" which is cast on the underside of the piston by one of the lubricating holes for the wrist pin. Wiseco pistons have a "W" cast into the underside.

Photo F - showing Mahle piston size 55.75mm, left and Wiseco piston size .020, right.