Let's face it; the chassis and suspension are usually the most overlooked items of a car project. More often than not, it is out of sight and out of mind. The majority of the budget goes towards the go-fast and shiny parts and what's left usually gets spent on the creature comforts. Unfortunately, back in the '50s automotive engineers weren't designing cars to handle 500hp power plants, quick acceleration, high skid pad numbers, and rapid deceleration. Combine this with the fact that a frame has been packed with rodent nests and dirt and you have the recipe for a poor performing and potentially faulty chassis. Since it is our goal is to build a '55 Chevrolet with sports-car handling, the focus of this project is the new AME replacement chassis and its updated, modern suspension.
Beginning with a stack of vintage GM chassis books, two classic Chevrolet frames and a blank CAD computer screen, Art and his suspension engineer, Katz Tsubai, got to work. While building a chassis to locate the bumper mounts, body mounts, and core support was a relatively straightforward task, the suspension was another story. Out back, the suspension needed to lower the stance and maximize cornering agility while not intruding into the trunk space. Up front, the challenge was the placement of the power rack, sway bar, and IFS towers, in relationship to the motor and firewall without sacrificing ground clearance or the vehicle's turning radius.
To address these challenges, sample 2x4 rails were mandrel bent and then test fit against the floor to maximize room for the suspension and exhaust. A frame width specific, triangulated four-bar suspension was then designed to capitalize on cornering while keeping body roll to an absolute minimum. Since the upper suspension bars were triangulated, it eliminated the need for a track locator, thereby making more room for the exhaust system. Even the shock cross member was designed to maximize the decreasing amount of available space. The Independent Front Suspension was scratch built by Katz Tsubai. Katz's goal was to design a suspension that offered late model performance handling and comfort. When finished, an IFS was created with an ARG power rack originally designed for the SCCA Trans-Am wars, optimum length control arms and a 1-inch antisway bar to control body roll. To address the age-old problem of using an HEI distributor, AME moved the motor forward 1/2 inch, eliminating the need to massage the firewall with a hammer. With the first prototype chassis built, it was then test fit under Art's cherry '55 and also against a '57 wagon and the measured against GM's chassis books. With everything checking out, 400 hours were invested into a jig table that would produce frames with a high degree of accuracy for years to come.
As soon as the first chassis rolled off of the jig, it was taken down to Oxnard, California, where Borla Industries designed a set of small-block headers and complete stainless steel exhaust. Capable of handling well over 600 hp, the high quality exhaust system is routed through the chassis' exhaust ports, over the rearend and exits just under the rear bumper guards. With the exhaust system mounted within the chassis, nothing hangs below the frame, a far cry from the traditional Tri-Five headers that only give you a few inches of ground clearance. After returning back to the Northwest everything was triple-checked and Borla was given the thumbs up to produce their own jigging to re-create this stainless exhaust system for all of Morrison's Tri-Five customers.
With the chassis, its suspension and exhaust sorted out, it was time to personalize our chassis and begin the final assembly of the frame and its components. The Tri-Five chassis comes as a bare steel frame with your choice of bare, powder coated or show-chrome suspension links. As we plan on driving the GT55 hard we chose the attractive, yet durable, silver powder coat links. The chassis coating is left up to the customer as shipping a finished frame, scratch free, is a risky business. We delivered the GT55 frame to Yorkshire Industries, a Tacoma, Washington, powder-coating business, where they did a beautiful job of laying down a zinc base coat (to prevent rust) followed by a high gloss light gray topcoat.