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I'm in need of a frame for my 72 but they seem to be slim pick'n. I have a line on a hard top frame. Can I use this kit https://www.chevyhardcore.com/tech-s...-from-hellwig/
and make the hard top frame a convertible frame?
No and NO. That Helliwig kit does NOT provide the same stiffness as the box sections on the convertible frame. It also does not provide the factory-style crossmember mounting, so using their proprietary crossmember likely means fabrication/mods are needed to hook up the e-brake cable. The OEM brake and fuel lines will require rework as well. If the boxing sections on your original frame are good, your best (and least expensive) option is to cut those out of the original frame and weld them into the unboxed frame. The outer rails are the same on both. Of course, this assumes someone with welding skills will be doing the work.
Joe, I've got some friends that did the Helwig frame mod and that frame is as solid as a Sherman tank. As far as the transmission xmember, it's not that big of a deal to fabricate and get the Ebrake cables to work. You do need to be a very experienced welder to accomplish this.
I can weld, that's not an issue. I'll have to look at my original frame and see what kind of condition the pieces Joe pointed out are in.
I appreciate the feedback.
Joe, I've got some friends that did the Helwig frame mod and that frame is as solid as a Sherman tank.
Based on what? Unless you've used a load fixture to measure torque required per degree of deflection, that's about as accurate a statement as your butt dyno. Sorry, but my day job has involved aerospace structures design and testing since 1980. Trust me when I say that they are not the same.
I would be concerned with warping given the amount of welding that will be done..
That much welding was done when the frames were made originally. Obviously one needs to follow best practices with fit-up, clamping, tacking, and finish welding. This isn't an 18 gauge fender we're talking about.
That much welding was done when the frames were made originally. Obviously one needs to follow best practices with fit-up, clamping, tacking, and finish welding. This isn't an 18 gauge fender we're talking about.
All metal moves when welding, especially 3' at a time. It needs done correctly or it'll twist. It could grow and shrink enough to really put some tension on pre-existing welds and crossmembers, which will cause other problems down the road..
the original frames were obviously welded together, but the order in which it was built is very different than what this entails and for good reason.
Last edited by 66_Jetstar; Aug 7, 2025 at 09:28 AM.
All metal moves when welding, especially 3' at a time. It needs done correctly or it'll twist. It could grow and shrink enough to really put some tension on pre-existing welds and crossmembers, which will cause other problems down the road..
the original frames were obviously welded together, but the order in which it was built is very different than what this entails and for good reason.
Well, the welds aren't three feet at a time. If you look at an OEM convertible frame, the reinforcements aren't continuously welded. Again, good practice would be to fit everything up, make small tacks at widely-spaced locations, then go back and fill in. This isn't magic.
Well, the welds aren't three feet at a time. If you look at an OEM convertible frame, the reinforcements aren't continuously welded. Again, good practice would be to fit everything up, make small tacks at widely-spaced locations, then go back and fill in. This isn't magic.
the OE frame rails were welded before the frame was an assembly. Adding this much material and the heat required ex post facto is going to create a lot of unitended pre-stress welds and stored energy in the frame. I'd bet most of the folks who install this kit wind up with cracks at some point, even in places they were no where near with the welder. This is part of the reason its "as stiff as a sherman tank".. it's going to be a clenched fist.
I do my own MIG and TIG. This is not a concern for me. People lose a whole lot of sleep over welding on frames. It's just mild steel. The factory production tolerances were looser than any warpage you will see from this.
I have cut out the boxing sections from a convertible frame and welded to another frame as Joe described, using a Lincoln AC welder (buzz box) and all went well. As he said, it is just mild steel and being about 1/8 inch thick, it is not a high tech situation for a simple AC stick welder.
