Old Britts – Crank Case Puller for Pre-MK3 Norton Commandos
Download the complete PDF version using the green download button at the top right of this page for an Old Britts workshop article covering the design and construction of a crank case puller for Pre-MK3 Norton Commando engines. This tool was developed as an improved alternative to an earlier single-center-screw puller, giving more controlled pressure when separating the crankcase halves while helping protect the exposed end of the crankshaft.
The article explains how the puller uses three threaded rods positioned around the crankcase and a shaped top plate that bears against the crankshaft area. Fred Eaton notes that the aluminum top piece acts much like soft vise jaws, reducing the risk of damaging the crankshaft end, while the three-point layout allows pressure to be adjusted unevenly if one side of the case needs additional help during separation.
Further sections provide key fabrication measurements, including the use of three 6-inch threaded rods, the 120-degree spacing of the case mounting points and the 2.5-inch distance from the crankshaft center. The guide also describes the slotted mounting holes, the optional center recess in the back of the plate and shows the full set of parts that make up the puller.
Contents Include
- Pre-MK3 Norton Commando crank case puller design
- Improved three-point puller layout
- Aluminum top plate to protect the crankshaft end
- Adjustable pressure across the crankcase halves
- Threaded rod sizing and end-thread details
- Mounting hole spacing and fabrication measurements
- Slotted top plate layout
- Optional center recess for stubborn cases
- Photos of the puller fitted to a crankcase
- Complete parts layout for tool fabrication
