Thread: Need some input

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Rodding is about modifying for sure. Backyard engineering is part of the process. That being said, there are a lot of practices that people "get away with" that pass for success. Lots of '49 to '54's have been "front clipped", and if I had to guess, based on years of seeing the good, the bad, and the ugly, at least half of them have been done wrong (from a safety and positioning stand point). As pointed out, with careful measuring and lots of trial fitting of the sheet metal, placement can be done well. Then the equally critical part comes, welding the clip on properly. Usually this entails not just welding the "new" front frame section to the "old" existing rail ends, but also fish plating and gusseting.

Now comes the point that will get the hackles up. I will acknowledge that, as pointed out above, there are a lot of Chev's out there that have "gotten away" with clipping. I had a '41 Chev that went for years with an extremely well done installation. The question might be though, how much real world use have they gotten to point up stress issues. Here's why I bring this up. There has been a fair amount of discussion over the years about the difference in chassis twist and stress transfer between the two types of frame rail design involved with the clip adaptation, and the rigidity of the mating zone. (some of you guys have your mind in the gutter here don't you? ) For those reading this not familiar with the Chev chassis, the original frame in your car is a formed "C" section, open to the bottom, with a riveted "boxing plate", to close it to a "square" section. They also didn't use an X center member so the torsional flexing went the entire length of the rails. The typical clips used (GM mid-size fronts from the late '60's-early'70's) are a formed "box" by welding two "C" sections together at their open ends. That gives the front clip section a different torsional action, when going over bumps, through dips, drive entrances, pot holes, etc., than the rest of the chassis. That stress difference will concentrate in the weld area where the two actions intersect. Now if the welding were done VERY WELL it might not show up for years, if at all. If the welds are "marginal" (which could span a very wide spectrum), then stress cracks could show relatively soon. It's kind of a wild card.

You might note that the original front suspension is bolted in rather than welded. This was intentional by the GM engineers because they understood the dynamics that they designed into the chassis. Just some things to think about. Here's a link to a tech article on installing the CE front suspension system I referenced above. http://www.rodandcustommagazine.com/howto/1603/

SPECIAL NOTE: THESE COMMENTS ARE PARTICULAR TO THE CHEVROLET FRAME AS NOTED!!


Oh, BTW, that business about the MII suspension being too light duty we've kicked around before. While it seems logical, at least superficially, because the Pinto was a "small" car, that suspension design was used on cars that had gross weights (Mustangs with V8, AC, PS, PB, etc) upwards of 3200#. Can't remember ever seeing any on the roadside with collapsed front ends. The Cad engine weighs very close to the same as the Stovebolt six. So, lots of things for you to consider.[COLOR=red][COLOR=red]