My personal feeling is that this idea that t-bucket frames have to be made out of 3/16" and ¼" wall tubing is not entirely true and may be misleading some into trouble. I wonder if a lot of guys aren't cutting up this nice heavy wall tube, getting out the brand new wire gun they just bought and laying down a fairly nice looking bead (just point it and pull the trigger and instantly you are a welder if you have a halfway steady hand) and then slicking it up with the grinder. Result - not much penetration because they don't realize that they haven't "wet-in" the weld. In other words, that nice looking bead was just kind of laying on the top with little penetration due to the heavy wall thickness soaking up so much heat. I've actually heard several stories about people laying down the most beautiful, even weld and it peeling up right behind it due to no penetration. That's scary! I'm not suggesting that using the heavy wall is not an acceptable idea, just questioning the idea that it is necessary. I think it comes with the responsibility of learning good fabrication practices or else the builder might be better off with a smaller wall thickness.

Back in the early days of the t-bucket world, all of the manufacturers used .120" wall rectangular tubing. Mostly 1-1/2" x 3", some 2" x 3". I wonder where that changed? My guess would be that some Johhny-come-lately manufacturer hatched it up as a marketing scheme rather than an engineering determination.

Why are T-Buckets in need of so much more in the way of a frame material than A's, '32-'34's and even the fat fendered models? Most of the aftermarket manufacturers of these use 10 Ga. (.134") steel in sheet form and use a multi-piece welded construction to form the box section of the rails. I would think that the rectangular tube would have some pluses in that it begins life as a steel strip that is cold formed into the shape with a single machine made weld. It seems that the rodders that are building the later models are not shorting them on horsepower or torque. Even late model pickup and vans use open channel frames that are not much, if any, heavier material than 10 Ga. It has always seemed kind of funny to me that the idea of such heavy material is so prevalent in this particular segment of the hobby. Danged if I know why!

These ladder type frames just plain don't have much torsional rigidity regardless of the wall thickness. Freeing up the suspension helps them quite a bit. A 4 bar car does not induce the twisting force into the frame that a hairpin setup does. An independent rear does not tweak the frame like a ladder bar does.

Just something to think about.

by George Barnes

O.K., I shot my mouth off and started this thread, so I guess that I ought to throw out my version of how I would build a frame.
For the main frame rails ( from the kickup to the front crossmember, I'd use 1-1/2"x 4" x 11 Ga hot rolled electric welded pickled and oiled steel tubing. Nothing exotic there, just the same stuff that most buckets are made from, with the exception of the pickled and oiled part. All that means is that the material has had an acid bath to dissolve the scale and an oil coating to prevent rust until fabricated. It's just cleaner to handle, and welds a little nicer with less undercutting at the edge of the weld. I would select the 1-1/2"wide material to give an extra inch between the rails. Sometimes that inch can make a big difference. Like when trying to fit a low mount alternator, steering box, master cylinder and brake pedal, or a whole bunch of other items. I selected the 4" tall material for a couple of reasons. The primary one is that I like frames that have some shape to them. To get that feature, I would taper the side rail from approximately 2" forward of the firewall to the front crossmember. The front crossmember would be made of 2" x 11 Ga. HREW P&O round tube. I'd shove the front crossmember out about 3" or 4" from where they typically are placed in relation to the radiator. The joint between the front crossmember and the side rail would be a direct geometrical fitup. In other words outside surface of the side rails on the top and bottom would be tangent to the diameter of the round tube. Just a little cleaner look. Another reason for the 4" sizing is that I would be using a 4 bar locating system for the front axle and that would allow for the notching of the top and bottom of the frame rails at the point where the taper begins at the firewall end. Sleeves would be welded into the notches for the radius rods to bolt to the frame. The radius rods would run parallel to the top surface of the frame and with a 4" center to center spread, they would give a nice slim and long look to the front.

Why would I use the 11 Ga. (.120") wall thickness material for this frame. The first reason is that I like the more "crisp" look of the corner radiuses on the material. As the wall thickness goes up, the radiuses go up even more. Just personal preference. The other thing is that I just never have figured out why a Bucket needs so much of a heavier frame than the later hot rod stuff does. The frames for A's, 32, 33-34, and the fat fendered years are all made of 11 ga. material by the aftermarket manufacturers. The cars weigh more than buckets, have every bit as much horsepower to deal with and I don't see any abnormal failure rates. If I go out and look under my van or a late model pickup, I see an open channel ladder type of frame that is close to the same thickness as I'm going to use. As far as being able to drill and tap the rails, I'm not planning on doing that. My approach would be to either sleeve the frame and use a through bolt or a welded tab with a hole. If I felt that I had to have a threaded hole in the rail, a Nutsert would fill the bill. They have more thread engagement length, are harder than the frame material and can be replaced with an equal sized Nutsert by merely drilling it enough to remove a small flange on the outer housing with the same sized bit as used for the original installation. Weight of the material would be a negative only in that it would not contribute as much as a heavier material to the sprung to unsprung weight ratio.
For the rear section that fits in the pickup bed, I would use 1-1/2" x 2" x 11 ga. pieces of the same material as the side rails. Why only 2" high? Again, to give some shape to the frame and to gain some extra room. The space gain could be used for additional clearance between the rear axle and the frame or more pickup box room for the fuel tank. The battery would be a Dyna-Batt unit that would require a mount to the frame rail in a horizontal direction. In that position, they are only about 3" tall. That would give more box room for larger tank or more storage.

The kickups would be done one of two ways. If I was going to use a standard structural shape rectangular tube and it would be a 1-1/2" x 3" x 11 ga. Some more of the giving shape to the frame. I would notch cut the kickup so that it would join the main rail and the rear section that were cut at normal 90 degree angles. I think that the weld would be better this way as it is in two planes instead of the single plane that results when done the conventional way. The problem is that if you want to run anything through the tube, the openings are reduced in area.

The other way that I have considered is to make a fabricated section of a top and bottom flange and an inner and outer side plate that would be welded in a box section. The profile of this section would follow the shape of the back of the body at that point and the bottom would start tangent to the bottom of the lower frame rail and curve up and gradually reduce in cross sectional area and then curve and end up tangent to the bottom of the rear section side rail.

I'd add one more thing to the base frame. It would be a K-member unit that would be a transmission mount, driveshaft loop, and it would help the torsional rigidity of the frame. It would consist of a tube that runs from one side rail to the other and would be flush with the top of the side rails, two vertical tubes that would be on each side of the tailshaft housing and then an "S" shaped tube on each side that would run from the side rail to the bottom ends of the vertical tubes with a sleeve mitered into the end for bolting on the transmission mount. Two tubes would run from the intersection of the tubes at the top to a spot in the area of the kickup. Another 2 tubes would run from the intersection at the bottom of the S shaped tube to a lower spot on the kickup.
Boy, I bet this description is about as plain as mud!
Welding would be all TIG and welds would be left as is. I like to see well done welding. Brackets would be mostly made of 7 ga. material and would be configured to be strong through design and not just bulk or mass. They would incorporate folded tabs and ears to gain strength.