I have a rusted out center x frame on my 55. Both main side rails are in good condition. The x frame is basically like a sheetmetal I beam on the Pontiacs. I already removed it and i'm debating just going with a trans crossmember and possibly boxing the frame in or making a new x-frame. The old section maybe weighed as much as a front fender, I don't know how much structural stiffness it adds to the frame to keep it from twisting? Has anyone built one? I was going to make it simple as possible. I don't have access to a tubing bender, but thinking 1 x 1 square tubing top and bottom and maybe like a 1/16" plate in between like a engineered joist in a house. I have 5" of height in between the center section of the open c frame . And also make some lightening holes and also for exhaust pipes. Any thoughts? Thanks in advance for any input.
The X is actually stronger in these cars than they appear.... even though they are sheetmetal. I have a bad spot on my X section (Driver's side rear leg where it attaches to the frame) I was contemplating doing the same thing you are thinking about and probably will do something with it. My car will be primarily a strip car so the frame should be stiff. I was going to do some changes that would resemble more of the after market K style crossmembers that they sell for '32 Ford frames and tie it into a 8pt rollbar. I was going to use 1"x2" rec tubing. I too was surprised to see how thin the metal in the X was! It's a wonder that they lasted as long as they do, especially since I have a rustbelt car it's entire life. If and when you do something I'd like to see some pics. Boxing the frame and using simple crossmembers would give you a frame similar to the '55-'57 Chevys....not that bad.
Hey Curly, thats were mine was the worst at also. My 55 lived in the rustbelt like yours. Maybe Art Morrison or someone already has some prebent stuff I may be able to use. Here's what the Pontiac frame looks like http://pontiacsafari.com/L1EarlyV8Pontiacs/56ShopManual/2 - Frame.pdf
If it helps, any 49-57 should be able to provide a donor piece. Usually the frame rots right where you put your feet on the left in these cars, and that's about it, unless it really sits in the mud and wet for years.
art make stuff for tri-5 stuff,us pontiac owners are kinda the "basterd child" of that era. if the pontiacs interchange like the chevys their should be lots of those floating around. sounds like simply replacing the frame would be easier. somebody here on the west coast probably has one. put a wanted add in the cl***ifieds
A good stock frame wouldn't do me any good for what i'm doing. I've already converted to a 58 ball joint front end, and the frame in the pic is/was my parts car. I'm using the rear section of frame rails 18" forward the front of the leaf spring bolt and will overlap there and mount them inboard , and the rear of the x-frame mounts to the inside of the frame at the front leaf spring mount. Another reason why I took the x-frame out. The leaf spring mount is on the outside of the frame and it will sit against the inside of the frame. Not real Hamb friendy but I'll gain 3" of tire clearance along with moving the wheelwells in some to match. 12" of tire will fit pretty easy.
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