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Tri-Five Chassis And Suspension - On The Drawing Board...

...and into production, the frame is the heart of this warrior

Craig Morrison Mar 1, 2004
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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.

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Freshly powder coated, the GT55 chassis is ready to assemble.

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.

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The front A-arms were powder coated as well. Art installed the bushings and the ball joints and is using a high quality anti-seize to prevent the bolts from galling or binding the front suspension.

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.

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Once the sway bar is mounted onto the chassis, the sway bar end link is bolted onto the lower control arm.

When we brought the frame back to the shop, we set it up on jack stands, turned on the radio, and let the assembly begin! While you can assemble your chassis in any order you want, we decided to start at the front suspension and work our way to the back of the vehicle. Assembling the front suspension is a fairly straightforward process as you can see from the pictures. Once the suspension was together and on the chassis, Art then checked for toe, and camber/caster. While this is a fairly technical part of the chassis buildup, you can get it close then have a local alignment shop adjust it once the car is finished.

The next order of business was the assembly of our bulletproof rear end. Starting with a freshly powder-coated 9-inch housing, we made sure to clean out all of the sandblasting grit before putting it together. We then installed the Strange Engineering nodular iron S-case complete with Positraction unit and our gear choice. After pressing the bearings on we slid the 31-spline Strange Engineering street/strip axles into place. With these top of the line Strange components in place our rear end is capable of handling 850-plus horsepower. Wilwood's Pro Series Rear Parking Brake kit will bring us to a stop in a hurry and has an integrated parking brake for when we need one. With the sway bar and suspension links already installed on the 9-inch housing, we bolted it up to the chassis, checked the wheelbase and that the rearend was square with the chassis. Once the Strange Engineering shocks were bolted up the suspension was complete and we were able to then focus on the brake lines and the Borla exhaust system.

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AGR's 15:1 power rack is attached to the front cross member.

While the brake lines were hand made for the GT55 project, Art Morrison Enterprises is in the process of offering a complete brake line kit for the Tri-Five chassis. Like the exhaust, the brake lines have their own through-frame passages so they can run through the frame rather than under it where they are prone to catching or rubbing on any number of road hazards out there. Bolting the brake lines into place is a trouble free task and can be done in no time at all.

The Borla exhaust system is another easy to install, bolt-together project. Starting with the H-pipe and working our way back through the chassis and over the rearend, the exhaust was a snap to assemble. All of the clamps were left loose as there may be a bit of tweaking here and there to get everything to line up with the Borla stainless headers. When we installed the engine and transmission, the headers were bolted up to the H-pipes and the exhaust was tweaked so it was centered in the frames exhaust ports. As soon as we were happy with the fit, Borla's stainless clamps were tightened down to ensure years of rattle and leak free use.

With the GT55 chassis now assembled, the next step is to mount the body and prepare the car for test firing!

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With the Strange Engineering "S" series case, Positraction, 31-spline axles and Wilwood brakes, this rearend is capable of handling some serious horsepower.

Building a car with aftermarket or late-model parts always requires a bit of homegrown engineering. A lot of measuring, head scratching, grinding, cutting, welding, and usually a ton of headaches. One of the most challenging projects has been to put a late model transmission into your car, have it fit, and have the shifter be in a comfortable spot. Usually placing a five- or six-speed trans in a your classic Chevy meant that either the shifter would come up through your seat or you would have to resort to some very unique shifters to get it in a comfortable spot.

Thanks to Keisler Automotive, Tri-Five enthusiasts can chose either a five- or six-speed with all of the engineering done for you. Based on the bulletproof Tremec TKO 5 speed or the equally tough T-56 six-speed, Keisler machines the transmissions so the shifter location comes through the floor in the correct spot, right where it needs to be without having to make major modifications to the transmission tunnel. In fact, most of the kits utilize the stock GM bellhousing (or SFI equivalent). Also available with the kit is the correct length drive shaft, speedometer cable, pilot bearing and any wiring that the transmission may need. With optional accessories including the hydraulic throw out bearing, clutch, flywheel and shifter handle, Keisler Automotive is a one-stop shop for everything between your motor and rear end.

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The Wilwood rear brakes include a 12-inch rotor with integrated E-brake and make for a stout overall braking package.

With both the TKO 5 speed and the T-56 six-speed, Keisler offers kits for two horsepower ratings: 475 hp and 650 hp. For the GT55 project, we chose the 650 hp T56 kit to take the abuse of our 530 ft-lb of torque. With first gear at 2.66:1 we will be able to have some stoplight-to-stoplight fun while sixth comes in at a freeway friendly 0.50:1. Our engineer, Katz, has calculated that with a 3.70:1 gear set in the GT55 and in sixth gear we will be able to cruise at 70 mph with only 1,700 rpm registering on the tach. Hard launches and low-rpm cruising, what could be better?

Keisler Automotive has many kits available including packages for the ever popular Nova/Chevy II, Camaro, Chevelle, Corvette, and of course the Tri-Fives. With more and more packages available every day, Keisler Automotive has taken a lot of guesswork out building a car.

In the last few years, the automotive aftermarket has seen a renaissance in the world of crate motor performance. There are dozens of companies producing numerous combinations for virtually every budget. One thing's for sure, the availability of streetable big horsepower crate motors have never been so great at such reasonable prices. To obtain the goals set for the GT55 project, we chose a Bill Mitchell Motown Small Block. While Mitchell has packages that range from 415 to 454 inches, we just had to go with the traditional combo of a 427 inches in a '55 Chevy

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Using a jack to hold the rearend in place, Art bolts the beefy 1 3/8-inch triangulated four-bar tubes into place.

Having been in the engine building business since the '70s, Bill Mitchell has enough experience to know what works and what is going to be reliable enough for long-term street duty. When you read the build sheet on one of Mitchell's Motown motors, its like reading a who's who list of the aftermarket that includes: Wiesco forged pistons, Manley 4340 rods, Crane camshaft, Speedpro lifters, Motown aluminum manifold, Modified Holley 870 Holley carb, Speedpro ring set, Milodon pan, Clevite bearings, HEI distributor, Fel-Pro gaskets, and ARP hardware. To top it off all of the Motown Motors are backed by a 2-year, 24,000-mile warranty. With all of this on the plate, it makes its virtually a no-brainer when it comes to making the decision whether a person should build their own motor or buy one of these killer Motown motors.

The motor arrived via truck freight to our shop and came complete carb to pan with its own dyno sheet to show that it has been run. Our particular 427 managed 520 hp and 530 ft-lbs of torque. After plugging the motor data into our computer simulator, the GT55 should manage 0-60 mph in the low-4-second range, run mid-12s in the quarter, and top out at just under 160 mph. Considering the aerodynamic challenges that a '55 Chevy faces, the Bill Mitchell Motown motor will be a true miracle worker!


Wilwood Engineering
Camarillo, CA 93012
March Performance
Naples, FL 34110
Strange Engineering
Morton Grove, IL 60053
Borla Performance Industries
Oxnard, CA 93033



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