I've got a 1" and 1 1/2" tube cage style frame from a modern style mini sprint. I want to stretch the wheel base 10". How do you secure (or can you) the horizontal tubes and keep them aligned once you cut them loose? I am pretty sure I can get REAL close to accurate and add additional bracing once I have the new wheel base. I just wonder how the BIG BOYS would do this. BILL RINALDI
Post some pictures of the area in question, please. I have stretched other tube contraptions by cutting half way through the tube, and then tack welding a piece of angle steel to the tube. Once that is on, I cut the rest of the way through the tube, and slid it down the vee of the angle steel. If you have say, four horizontal tubes, you could strategically place the angle steel to keep the alignment. Then it is measure, measure, measure, then tack the other ends of the tubes on. Were it like that I would then add extra bracing, facilitating totally replacing the cut tubes, one at-a-time.
I am looking at pictures of numerous different chassis on the web. I am not seeing too many that will lend nicely to being stretched, though.
Yeap! They are not like an early Formula Ford, there hardly a parallel tube on these things, everything tapers inwards or down at the front
Not for the faint of heart. Gimpy pretty much nailed it. Angle iron tacked on each section, then replace the tubes rather than splicing them. Vinney has that heavy "bench", which could give you a flat surface or fixture to assist in keeping things going in the right direction.
As suggested by Stu D Baker, with a suitable flat surface, you might consider an enlarged version of Gimpy's suggestion. That is, build a pair of rails or tracks long enough, and sturdy enough, to support both front and rear sections of the chassis. Attach 'sliders' to the forward and rear chassis, then sever the tubes to be replaced, and slide the two sections apart the distance you choose. At that point you can proceed to remove the severed tubes and replace with longer sections at whatever angle required to reconnect the forward and aft chassis sections. If the angles change very much it may require some estimation of how much that would affect the strength, if any, of the original design. Ray
Bring it to my shop (Brownsburg, IN) Bill and we can put it on my dragster jig. It has adjustable saddles (height and width) to locate the lower rails. That said, every mini sprint that I have seen has the top of the cage raked down toward the front at least a little and that would be a problem. If all of the tubes that you plan to cut are parallel then it would be easy. Roo
As mentioned, if the frame is tapered (and it probably is) you really can't just easily splice in 10 inches. In the past I have restubbed wrecked sprint car frames by cutting everything off in front of the cage then used inner sleeves and built out from there. Adding 10 inches will make the front narrower than original but probably not enough to be a problem.
Unless ALL the tubes are square and parallel its nearly impossable to get them looking right. Pictures of what you have is very helpfull when asking questions like this as it eliminates assumptions on our end and a more direct answer can be given.
This whole stretch the frame thing is an idea rather than a necessity. The best part of this build is it's a functional finished thing as opposed to structural pretty thing. The frame work/tubing is covered by body panels. This "midget" is a visual reproduction, NOT an authentic one. Actually it's an idea that I'm finally doing some thing with. Stu and I have a buddy with a very workable flat plane table that would be really good for this. I think you guys that propose setting it up on a dedicated flat surface with movable plates will probably work the best/easiest. Thank you all for your input. It may take a while for the next move, but I'll throw a reply when it does. BILL RINALDI
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