[David_Hayward (RIP)]

Rolf asks (sorry for the pun my friend, not intended) about the choice of 216 Chevy engine. Here is some information from the DND papers that I have posted before:

Carmichael, the GM of Canada General Manager, was present at the trials [Ontario, early summer 1939] and he advised that the company were anxious to produce two units for testing by the DND, and that they could be made to any specification laid down. No mention of purchase was made and it was afterwards intimated to [Colonel N.O. Carr aka "No Car"] by Kirkhope [J.L. Kirkhope of GM of Canada] that there was no intention of selling the units to the DND. Carmichael was informed that Carr was ready to lay down a specification which in his opinion was the best to follow for two experimental vehicles; that he could see no special advantages in the designs then being called for if they were regarded from the viewpoint of the WD and the knowledge he possessed in regard to the latter’s aims, but he felt that it might be better to draw up a specification after consulting other possible consumers. Carmichael waved aside this proposal and intimated that the DND should produce what they thought was the best vehicle and left it to them to try to sell the idea abroad. He took him at his word, he said, and discussed in detail with the GM Chief Engineer, Armstrong, and Kirkhope the design to which he thought the two vehicles should be produced. This was that both vehicles were to be of minimum wheelbase, estimated to be approximately 108-inches. Both vehicles were to have the front end redesigned to admit of the driver being placed as far forward as possible. Armstrong suggested that he thought that by using the widest track available the driver could be positioned so that his feet were well up beside the engine. If this worked out satisfactorily then the loading space behind the driver should be equivalent or very nearly so, to that of the 15-cwt. [this must have been a reference to the 1938 GS Trucks]. Both vehicles were to be fitted with cowl and windscreen only and bucket seat. One vehicle was to be fitted with the standard Chevrolet [216] engine, and the other with a larger engine, which had only recently been developed, namely the [US 33.19 hp GMC] 248 cu. in 6-cylinder . One vehicle was to be fitted with 13.50 x 16 tyres and the other 9.00 x 16 tyres, single wheels all round. These specifications were presented to Armstrong as an ideal to be aimed for and a formal response in writing was promised. However, Carr envisaged a difficulty with the production of the wheels for the 9.00 x 16-inch tyres as the offset required on the front axle was very large. The double-flanged wheel as produced by Kelsey [Kelsey Wheel Company Limited, Windsor, Ontario] would not meet requirements. There was however a possible solution as India had ordered on their truck the fitment of 13.50 x 16-inch tyres and had told GM that they were to proceed with the obtaining of this equipment. This item had held up the production of the truck for India for some time as it was thought initially that the fitting of a wheel of this diameter would be impossible. The standard brake drum was about 14-inches in diameter, though after further study in conjunction with Timken, it had been decided to fit an 11 to 12-inch brake drum that would take a 16-inch wheel. If the spider of such a wheel was produced then in order to convert it to use with a 9.00 x 16-inch tyre would simply require the importation of the rim from [Dunlop?] England. It was further understood that 13.50 x 16 tyres were by then obtainable in the US and that the Dominion Rubber Company Limited were also about ready to start Canadian production as well. GM were then busily engaged on the 1940 Models [launched 20 October, engine production for 1939 Models stopped in June, and 1940 production started in August], hence Armstrong thought that it would be most unlikely that these two experimental trucks could be produced before the end of August, but ‘he would do his best’. Carr rode in the truck bound for Malaya, apparently around Durham County, which had been fitted with 13.50 x 20 tyres, and about 20 miles were covered on a back country road with a maximum obtained of 43 m.p.h. The truck was said to be very unstable as the final front-end geometry had not been set-up. However, the GMC truck, for that is what it was, allowed the disengaging the front axle and had an auxiliary gearbox [2-speed] providing for a total of 8 forward speeds and two reverse. Caldwell, the MGO, commented in handwriting on the original note that he found the information ‘very interesting’. He was of the opinion that it was advisable to go ahead on ‘our own design’ based on known British trends and concurred in Carr’s action in the matter. He commented ‘anything we produce on these lines which is satisfactory to us is likely to be at least generally satisfactory to other Empire countries’. There is no direct evidence but circumstantial information from Stan Ellis’s letter of 10 November 1939 from London which is set out in greater detail below, seems to suggest that one of these trucks was shipped to England and tested in the autumn...

My comment: this seems to suggest that GM of Canada had agreed in late 1939 to produce two ‘1940’ model GMC-based trucks based on a cowl and windscreen only and Forward-control. Reference to a 108-inch wheelbase suggests that the discussion was concerning the 1940 Models Maple Leaf 1858 and GMC 9858 C.O.E. 2-ton chassis with cowl which normally had either the 216 Chevrolet unit or the larger 224 GMC unit, and the GMC 248 would have been a special fitment. GM of Canada therefore agreed to design their two pilot trucks loosely to WD-specification. Did they however agree to add their own cab design to WD requirements? It is more likely though that GM delegated the cab design for fitment to GM chassis to Ford of Canada, no mention having being made to Oshawa building a cab: quote: ‘both vehicles were to be fitted with cowl and windscreen only and bucket seat’. Fords were at the time occupied with the DND 15-cwt. GS 4x 2 Trucks with the WD-specification cab, and an adaptation thereof went into series production.

The Canadian GMC 248.4 cu in. unit had a bore and stroke of 3 23/32 x 3 13/16 and production started in August 1940 and finished in June 1941: 6,573 in 1940 and 10,464 in 1941. Compare this with total 216 (and 224?) production for 1940 and 1941: 71,627 and 106,935! No attempt was made to produce the 270 GMC unit in Walkerville. As you know the 270, imported from the US plants was requested for the C60X, and then installed in armoured CMPs. However, Ford offered their Lincoln Zephyr V-12 for a 6-wheeler CMP, and the Chrysler straight eight was trailled in a VC60X airportable. Why the Chevy-based Pontiac 224 was not chosen as this offered more power, and was used in Maple Leaf trucks, I have no idea. I can only surmise that the commonality with the US 216 that was mass-produced, and the thought of spare parts supplies in the future, led to the adoption of the 216.