C30 Chassis

[Grant Bowker]

By coincidence we were walking around the CMPs in the field today and the width of the frame (outside of rails) is 34".

[Charlie Down]

I got some measurements for a chevy Blitz chassis courtesy of Allan Mazlin, from MCP Vehicles Australia. I've added the measurements to my comparison slide of the MCP chassis for clarity. The MCP Chassis is wider at the back and narrower at the front compared to the CMP chassis. I would have thought the CMP would be wider for military use to make it stronger and more stable. Surprising result. Also the spring hangers seem to be arranged differently. According to the GM Heritage site the MCP rear springs with auxiliary leaves were 46" or 1168mm long and 2-1/2" 63mm wide. It would be interesting to compare blitz rear springs to see if they have been modified (lengthened or shortened) with the rest of the CMP Chassis. I believe the MCP chassis had extensions to fit the Military front bumpers on, which made the chassis even longer.

[Hanno Spoelstra]

Good work Charlie.

See http://www.mapleleafup.net/vehicles/.../chevspec.html for spring specs

[Grant Bowker]

I'm not sure when it started (one source gives 1938) but I'm fairly certain that the 34" outside width of frame rails is a SAE standard, established to permit interchange of bodies between chassis of different manufacturers (to save body makers from having to make different bodies for Ford, Chevrolet, Dodge, etc.). In the same vein, the distances from back of cab to rear axle are also very close to standardized - for the same reason.
One reason that the lighter modern pickup trucks still have wider frames is that they are pretty much designed to have proprietary bodywork and single rear wheels rather than specialist manufacturer bodies and dual rear wheels.