A lot of good things can be said about the evolution from the first to second generation Camaro. For example, the '70-81 cars had vastly improved suspension geometry, larger factory wheelwells, and a more aerodynamic fuselage style body. But one thing definitely not on the list is excellent structural rigidity.
Unlike most unibody designs where the front subframe rails are welded flush to the floorpans in several locations, second-gen Camaro subframes are attached at only four bolt points with body mounts that have a surface area of only a few inches. While there are real advantages to that design, including easy removal and replacement, it also means all the twisting and bending force of suspension travel and uneven road surface is transferred to a small area of thin steel rather than being spread out over a large surface area.
In stock form, soft springs and rubber body bushings squelch a lot of that abuse, but when upgrades like stiff springs, aggressively valved shocks, and solid body bushings are added in pursuit of lateral performance, all that force has to go somewhere. With the stock subframe in place some of the force would dissipate by distorting the weak rails, but with the increased torsional rigidity of our DSE hydroformed front subframe bolted in place with solid aluminum body mounts, most of the force would go into Project F73's sheetmetal. If you had a camera mounted underhood, the flex would be clearly visible.
DSE's subframe connector kit...
DSE's subframe connector kit is a simple looking package with a lot of engineering and testing behind it. They weren't designed to be an easy install; they were designed to be as effective as possible. To help simplify the process, the kit also includes templates, pictures, instructions, and a step-by-step instructional DVD.
While metal fatigue is a real concern, especially from frequent hard driving or track days, the most immediate concern is that deformation and flex will rob our ride quality and cornering potential by altering the geometry of the front suspension and the contact patch of the tire. Not a big deal in a regular street-driven Camaro, we suppose, but who wants to think they're not getting their money's worth out of their new suspension?
What's the solution? It's as simple as a good pair of subframe connectors. The problem is, we need more than a standard set of connectors that hang under the floorpans and bolt or weld to the front and rear subframes. While those do help somewhat, there's only one way to install true subframe connectors-and it involves lots of cutting.
Like other subframe connector designs out there, DSE's design increases the car's stiffness by connecting the front subframe to the rear framerails. Unlike others, DSE's subframe connectors are flush with the subframe assembly, without curves in their shape because the large rectangular steel tubes are integrated into the floorpans. By installing the connectors in this manner they become part of the car, greatly increasing their effectiveness.
It was a solid day's worth of work to prep Project F73, then another to install the rails, but it's time well spent to ensure we're not compromising all of our other efforts to increase lateral grip.
What We Did
Installed Detroit Speed and Engineering's subframe kit for '70-81 Camaros and Firebirds.
We greatly reduced the bend and flex in F73's chassis.
$185 for the kit and it includes an instructional DVD.
The rear subframe is welded...
The rear subframe is welded to the body making it significantly more rigid than the front by installing through-the-floor style connectors. We're essentially extending this strength through the Camaro's tub and permanently attaching it to the front subframe.
Remember the old carpenter's...
Remember the old carpenter's saying here: "measure twice, cut once." We measured a half dozen times and sketched out the area to be cut with a soap stone. This needs to be a precise cut, so take your time and use a sharp cutoff wheel.
Adding the subframe connectors...
Adding the subframe connectors will require you to gut the interior and there's no way around it. To gain full access, part of the cutting has to be completed topside and the connectors need to be welded on both sides. Whatever you don't remove should be covered with a spark-resistant shield to avoid hundreds of tiny pock marks from waves of sparks. (We're planning on replacing that seat anyways.)