Old Britts – MK3 Crank Case Puller
Download the complete PDF version using the green download button at the top right of this page for detailed information on the Old Britts MK3 crank case puller, a practical workshop tool designed to safely separate stubborn Norton Commando MK3 engine cases without resorting to screwdrivers, mallets or other methods that may damage the crankcases.
This Old Britts technical article explains the design and construction of a simple but effective crank case puller made from threaded rod and aluminum bar stock. The tool was developed specifically for separating difficult Norton Commando MK3 cases while applying steady, controlled pressure to the crankshaft end and left crankcase mounting points.
The guide includes useful dimensions, material suggestions and machining notes for anyone wishing to fabricate a similar puller, including the spacing of the case holes, slot sizes, threaded rod preparation and the optional central recess used to help steady the puller over the crankshaft.
A real-world example is also described where the tool was used to free a particularly stubborn MK3 engine case with a rusted front dowel, demonstrating how gradual pressure and careful heating can separate the crankcases without causing damage.
Contents Include
- MK3 crank case puller purpose and design
- Safer alternative to prying crankcases apart
- Threaded rod and aluminum bar construction
- 5/16 x 24 threaded end preparation
- Puller bar slot dimensions and spacing
- Center recess machining notes
- Controlled crankcase separation procedure
- Handling stubborn or rusted locating dowels
- Use of gradual pressure and localized heat
- Complete puller component overview
