Bell Housing Patterns

This job was completed in June of 1996. The part is a bellhousing to adapt a Chevrolet block to a Hewland transmission. The Hewland transmission is mid-engine style. This setup was used in the older European full-bodied race cars.

The pattern was built first. We had only an existing part to work from. This tooling was truely reverse engineered. The hole layouts were taken from this part on the Bendix 1816 CMM, then laid out in Ashlar Vellum CAD. Expanded paper dolls were plotted on our Calcomp 1025 pen plotter. The coreprints were dry-jointed onto the pattern and a cast was made for the corebox. The cast was made using Freeman Manufacturing Repro® surface coat, Repro® laminating resin was mixed with 1/4" glass fiber shards and then applied at a thickness of 3/4" to add structural strength to the plywood ribs in the back of the box. The coreprints were removed after the corebox and pattern were separated. Their tops were decked off .100", then a .100" shim was added to the bottoms. This in effect expanded the coreprint geometry so an airset sand core from the cast plastic box would fit in the print depressions left in the sand. You cannot put a 1" sand core in a 1" sand hole very easily! The metal thickness was lagged into the plastic corebox with small mosaic tiles of mahogany milled to the right thickness. The joints were filled with CA glue wicked into baking soda filler. The gingerbread was then added in the corebox and to the pattern. Work by Dick Hill.

These photos shows 2 sample castings we poured in house off the tooling, validating the work. Another foundry will pour production needs.