1940 Chevrolet Cabriolet chassis design question

Someone else apparently brought this up some time ago but did not see an answer so I thought I would give it a go with new people here?

The Chevrolet Convertible (Cabriolet) was not produced for 1939 but reintroduced in 1940. The chassis design looked chaotic and massive yet in the 1941 information it stated that they redesigned the chassis once again this very next year. It was stronger and weighed about the same but did not use all of the channels, bracing, rail stiffeners, or heavy plates that the 1940 used. They all but said that the 1940 design chassis was a failure. The 1938 did not use an X or Y-K design on the convertible but side rail stiffeners. The 1940 was close to a Y-K design but not quite and had a massive cross beam and a large heavy plate in the center. The 1941 was a more traditional X brace design.

Question is, who and/or why was this 1940 design even used since it was not shared on any other GM car, or even remotely close in design to any other vehicle's chassis layout? And then immediately completely retooled the next year.

Thanks!

Jim

Just checking in to see if anyone has an answer as to who the mechanical engineer (frame) for the 1940 Chevrolet (particularly convertible) and if there was a rational explanation as to why they used an odd cumbersome design for one year only on one car only? Thanks...

Jim

No takers on this question? :confused:

I can only guess about this. Didn't they bring out a new front suspension for 1939 with control arms instead of the Dubonnet system? This would have required a new chassis. They also went to a new body design that year. Convertibles need reinforcment of the chassis and body because they have less strength and rigidity than a closed car. So, it appears the chassis was strong enough for the regular cars but not for an open car.

In 1941 they got an all new car again, that continued with face lifts until 1948. Evidently they got that one right, probably taking advantage of lessons learned on the 39 and 40.

I can only guess about this. Didn't they bring out a new front suspension for 1939 with control arms instead of the Dubonnet system? This would have required a new chassis. They also went to a new body design that year. Convertibles need reinforcment of the chassis and body because they have less strength and rigidity than a closed car. So, it appears the chassis was strong enough for the regular cars but not for an open car.

In 1941 they got an all new car again, that continued with face lifts until 1948. Evidently they got that one right, probably taking advantage of lessons learned on the 39 and 40.

Of course there were no Chevrolet Convertibles made for the 1939 model year. The 1938 did not utilize the X of any kind on the convertible. There were only minor differences between the 1939 and 1940 chassis and both still used the knee-action suspension. Only difference in frame rails was length for a longer body-wheelbase and lower sitting body. And the only difference between the 1938 and 1940 convertible was the addition of a rear passenger area instead of a rumble seat. True, they did a facelift for 1940 and again for 1941 which was unusual for such drastic tooling between a single year two years in a row. The same for the convertible chassis design which is whacky to say the least the way it is laid out and no other vehicle in the GM or any other manufacturer, used such a layout and apparently by their own admission, was a failure and not as strong as they expected. It is odd that they would not have simply used a tried and true design that had been an industry standard for nearly 10 years by this time? But they went off and made something that isn’t mentioned in brochures or even shown in shop manuals as if they did not even claim that the convertible frame even existed for 1940? There has to be some backstory on this one :confused:

I am still not coming up with any plausible nor rational reasoning as to why Chevrolet designed the convertible chassis this way and for only one year, especially with a penny-pincher in the division’s office?

I thought of looking at other GM products but Vauxhall was unibody then and there was an odd chassis under the Opel Super 6 but nothing like under the Chevy. And think Holden were Buick based then?

Good Afternoon everyone, bringing this back up to the top and hoping someone else may have ideas concerning the 1940 Chevy Cabriolet chassis? 

Thanks!  Jim