Using the original frame for my 31 A build. I welded in new front cross and kicked the rear up 5 inches using the rear cross sold in Speedway. The rails are straight and I built the frame on a level floor using weight and tie downs to keep frame from drawing during welding. The frame is also boxed. Long story short, I have fab skills and did the best job for what I had. I got a half inch twist from right front horn to back left corner. I can stand on one corner and someone can stand on the other and the frame goes flat and is level. There is no middle cross installed as of now. I'm thinking the weight of engine, trans and body will help level out the frame. I'm going to bring the frame to level when I install middle cross. Will the stress cause problems later on when car is on the road? It seems the front cross is where the stress will be, as it has to give to let the frame go flat. The rear is built much heavier.
A ship welder - straightener, or a tank builder [brewery], can show you what to do... heat here and spray water mist there... they know... I pulled both "inner and outer left '34 frame rail" 1/2" left to right with a torch and his soap stone marks... it bakes the carbon from the steel and makes it shrink... like he had said heat it red then go have lunch to let it cool... 1/2 hour later it had bent both left rails 1/2" to the right... gently tapped the front crossmember in, measured then tacked it... I had tack welded a "straight" 4' section of 3/4"x 3/4" tube to the flat bottom edge of the stock '34 tranny mount using angle measurements to triangulate it, for use as centered location points... thanks paul.
My opinion, you gotta get that warp out. You'll be chasing it around a bit but the work will be worth it.
...you know that's a 1/4 " out on 2 corners,..I doubt that'd be much of a problem when the car's all done....am I wrong?
Simple, put a 4 or 5 inch block on each of the 2 low corners. Have your buddy stand on one high corner and you on the other. Try bouncing on the high corners to see if it will easily twist over the blocks. It shouldn't take much to get 1/2 out.
You must straighten it before going on. I had the same problem....frame twisted as a result of frame boxing. Took it to a body shop with a frame straightener and $75 later it was straight. Another guy did his at home in his shop by jacking it using a hydraulic jack. You jack it a little over center and then see how far it relaxes back. Cost = $0. If you don't do it now then every piece you add will reinforce the twist.
Is the frame boxed now? A stock frame is far from having any exact tolerance. If it's not boxed and you plan on doing it. I'd say cut the front crossmember loose, jig the frame, box it, and reinstall the front crossmember.
1/4 inch on opposite corners is almost within Henry's tolerance. If the front and rear axles and the radius rod mounting points are square with each other it doesn't matter if the frame zig zags. You might need a couple more shims under the body. Your probably 1/8 inch corner to corner on the body. That ain't bad. Of course we all expect perfection, get it as close as you can and call it good.
My wife's Uncle laid the block foundation for his own house (he's not a homebuilder) and then cross measured and found it was a couple inches out. He knocked the whole thing down and started again. Absolutely nuts. But on a car frame I think I'd try to push/pull it into shape before going any further. Like said above, a couple blocks and heavy buds should work. A trip to a local frame machine would definitely work if you cant get it at home.
When cross measuring I try to get it closer than 1/8"... to henry they were cars, to us they are dreams and then treasure... . I had the garage builders set a 4" section of 4" pipe with a 5/8" rod slid through a couple holes cut through it, the pipe pointed up into the concrete... taped off the top so no concrete gets in... when set tap the slab to find it [hollow sound] … knock out the "cover" … now you can hook a chain under the rod to straighten a bent axle... if you have that it and a jack can put some beef to a bent "anything" … HIH...
I decided to cut the sides on the front cross member, on the low side. Left the top of cross welded in. Applied weight across the front of frame with a beam and concrete blocks. Heated the top of cross red hot on low side. Let cool, then removed weight. It's within a sixteenth of level. Close enough. Then I reapplied weight and welded the cuts back on the sides of cross. Thanks for all of your help and interest.
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