Chevy Tri-Five Frames - How It Works

Chassis pros dissect the inner workings of aftermarket frames for Tri-Five Chevys

Stephen Kim Dec 29, 2010 0 Comment(s)
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R&D

Matt Jones: Engineering a brand-new frame is a tremendous technical challenge. The very first step is to conduct some market research to figure out what most customers will want and what they may expect. For instance, are they willing to trim some sheetmetal for aftermarket transmissions or larger tires? Will they want the largest tires possible, front and back? Will the vehicle be raced at autocross events or just street driven? The next step is closely studying the vehicle platform for which we plan to design a frame. While most vehicles are said to use the same frame design throughout a generation of model years, the truth is they are usually different. Bumper mounts typically change, as well as rear ’rail design and body mount locations. All changes must be found before the design process begins. Next, we examine how the OEM frame is packaged in the vehicle. Most vehicles do not allow for a 335mm-wide tire without moving the framerails inboard, but care must be taken to see how much the ’rails can move without significant changes to the body or other components. The floorpan will dictate what suspension can be used, and how low the vehicle can sit. From there, the process gets much more high tech as we digitize the OEM frame and body. Using a Faro arm-measuring device, every important detail is digitized in 3-D to determine where to place the engine, bumper, and body mounts. At the same time, gauge or tooling holes can be mapped to later check our sample frame for possible damage to ensure we record valid data. Also, body mount location is compared between the frame and body to see where possible differences lie. Lastly, the floorpan shape will determine how narrow the framerails will be, how low the vehicle can sit, and which suspension will package the best.

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Install Procedure

Craig Morrison: The amount of time and effort it takes to install an Art Morrison full-frame kit depends on the applications. Some cars, like ’58-64 Impalas, required significant modification to the floor because of how low the floor hangs down. Depending on the skill level of the individual building the car and how intricately the new floor is designed, the installation process can take between 40-80 hours to install. Fortunately, that’s not the case with ’55-57 Chevys, as the body design lends itself very well to an aftermarket frame, the installation process is very simple. There are a few tabs for routing the OEM emergency brake cables that need to be trimmed off, and the original pinion snubber needs to be removed. Other than that it is a bolt-on project. With Art and I working together the first time, we were able to make the chassis swap in about five hours. With the body off of the frame, installing the suspension components, brake lines, fuel system, and engine and trans is much easier. For the dramatic improvements in ride and handling that our Tri-Five aftermarket frame offers, the time required to install one is a small price to pay.

Tubing Shape

Craig Morrison: When building a chassis, round tubing and square tubing each have their own sets of pros and cons. Race cars are built from round tubing, while production cars are built from square tubing. The primary benefits of building a round-tube chassis are strength and reduced weight. Since a rollcage is integrated into the chassis design, the overall chassis is extremely stiff and provides a very rigid platform for mounting the suspension. While lightweight, this space frame approach requires massive amounts of fabrication and usually requires a builder to hand fabricate every panel in the car except for the exterior body panels. A more traditional rectangular chassis that fits under the floorpan is generally a lot easier to install into a car, but because it isn’t welded to a rollcage they usually aren’t as rigid as a full round-tube chassis. From a street car standpoint, the fabrication is straightforward, you can keep a stock interior, and the car is easier to build.

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