Re: HPI vs Speed tech vs hellwig vs abc
I'm in the middle of both a Hellwig and ABC installation on my 71. The Hellwig is going on the C-channels as you would expect, and I'm using the ABC pieces to box in the frame behind rear. It's probably not worth a whole lot to box in the back end, but I wanted to go the distance on the frame.
I chose the Hellwig because of the numbers they put up about its increase in stiffness. I think the data is actually in one of the older posts here. The frame is something like 3 times stiffer than stock. I think the plain ABC-type boxing on the C-channel was only about twice as strong.
I have a 68 convertible, and I can absolutely say the convertible frames are vastly stronger than the coupes. The Hellwig mimics the convertible frames. I also like that it adds an additional frame to body mount.
What's more, I got the supplemental body bushings from Energy Suspension to utilize the unused factory floor brace mounts over the center of the C-channel. My body has the nuts in the floor brace, but like most Chevelles, it originally used the blank body mount. So, I'll be going from no body mounts in the center to two on either side.
Once all that's done, I may look at adding a cross member between the lower control arm mounts with cut-outs to clear the driveshaft and exhaust. I'll have to see how motivated I feel at that point.