A little bit of welding talent...
A little bit of welding talent will get you going. The key is not to make any value-diminishing changes in the visible frame sections and still increase its stiffness so that it handles better over the bumps and twists.
Not all frame exercises have to entail large suitcases full of money. Oftentimes the simple route can also be the most inexpensive, but remember many times there is a trade out. In this case, our '58-64 GM frame needed a redo to handle today's driving chores but more importantly-on a budget.
At first look, you'd think any early GM full-size car would have more than enough structure to handle any kind of engine power we could conjure up. But the fact is the '58-64 GM vehicle used an X-frame that could use a bit of help to increase its resistance to flex for better road holding ability and to avoid those pesky squeaks that are common with these full-size machines. In addition, when you factor in the additional horsepower often tucked between the framerails, we knew some additional work was in order to keep things together.
The GM X-frame is a simple structure: an X-frame of metal with coil springs front and rear to support the body and create the suspension mounts as well a few crossbraces to keep it square. The system is so simple that the body attaches only to the front and the rear of the frame, the centersection devoid of any attachment points, another reason for spending the time to bolster the frame strength.
The '61 Impala has proven to be a great project and challenged us to think uniquely about its restoration and ultimate use. We stripped off the old suspension components, bushings, and hardware and checked the frame for straightness and integrity (translation-rusty thin spots). By taking measurements on the diagonal from corner to corner, we determined that the frame was in great shape, straight, and true.
Next we media blasted the metal clear of years of age and debris. Luckily, there were no areas needing repair or straightening. Even the framehorns, which are commonly bent, were fine. Key to the strengthening program we were conducting would be the creation of a welded metal enclosure to support the X-frame itself. Basically we would design a custom "box" to encapsulate the frame. We started with cardboard templates so we could test-fit the pieces that we would later create from metal.
Follow along as we demonstrate the basic techniques involved. Regardless of the style of vehicle you have, taking the time to improve the strength of your vehicle's frame can only be beneficial for handling and durability.
Step one was to properly support...
Step one was to properly support the frame and outfit ourselves with protective wear. After the frame was properly cleaned through degreaser and media blasting, we inspected the surface for obvious damage and welding flash from the factory.
As any engineer will tell...
As any engineer will tell you, the thinnest point in a structure is also the weakest. The X-point is the weakest and where we will be adding material to the frame. This template shows the shape of the first piece of metal support.
We selected a piece of heavy-gauge...
We selected a piece of heavy-gauge metal and used our plasma cutter to carefully cut the shape. In our case, 1/16-inch-thick metal was used, thick enough to dramatically increase both the strength and smooth the looks of the GM factory frame but add limited overall weight.
The edges of the metal were...
The edges of the metal were ground smooth to create a clean joint at the point where subsequent pieces of metal will meet.
While hidden from view when...
While hidden from view when the body is in place, the frame seam is a point of weakness as well as just simply unsightly. We ground the seam down and welded the joint over again for added strength using the Miller Electric Millermatic TIG welder.
Note the important crossbrace...
Note the important crossbrace structure, it is perimeter welded to the frame all the way around, significantly improving on the factory's spot-welding effort.
Using the small grinding wheel,...
Using the small grinding wheel, the frame was cleaned of the welding splatter found in the rear section of the frame.
When cutting metal, a Tennsmith...
When cutting metal, a Tennsmith shear, is the best way to make a clean, even cut without bending the material. By having created templates to match the shape of the metal panel, we avoided wasted material and improved the final fitment.
To make the corner creases...
To make the corner creases in the metal required to wrap around the frame sections, a Tennsmith Handbrake was used. This Handbrake can easily work with up to 16-gauge material.
This metal covering fits nicely...
This metal covering fits nicely around the factory structure and was tack welded in place.
After cutting the side panels...
After cutting the side panels to the correct size, they were pulled into place with a C-clamp before welding. Work the metal down slowly to avoid crimping the metal during this process.
Avoid overheating the metal...
Avoid overheating the metal to keep from warping the surface. The welding process continues all the way around the point of contact to ensure the most efficient structure possible and to avoid annoying squeaks after you are done.
When making templates, a heavy...
When making templates, a heavy stock cardboard works great for simulating the basic metal pieces we require. With these compound shapes, it is important to test-fit to avoid costly mistakes.
This complex panel required...
This complex panel required us to use the plasma cutter and carefully cut the piece to the template shape. We also reground the edges smooth like the previous parts to ensure a clean welding joint.
Along with the side of the...
Along with the side of the freshly cut panel, the top and bottom surfaces were ground smooth to take down the edge that can form when cutting.
The final frame boxing panel...
The final frame boxing panel is installed, connecting it to the side panels already in place. Make sure to plan for any bolt holes or openings that will be required for component mounting or requiring clearance for shifters, engine mounts, linkage, speedometer cables, or anything else that will not operate if blocked.
Our plasma cutter was great...
Our plasma cutter was great for poking a hole in the panel once in place. Once the hole was made to the proper size, the edge of the panel was perimeter welded again for structural reasons.
Once the welding is complete,...
Once the welding is complete, a grinder was used to smooth the edges at the welding point. The overall look is plenty strong and equally good looking. Once complete we applied Rust Defender to keep it from rusting, as raw metal of this type is prone to do.