Tri-Five Chassis - Framing A Classic, Part 2

Bringing Up The Rear Of Our Chassis With A 10-Bolt, Lowered Leaf Springs, And Traction Bars

Damon Lee Jun 1, 2000 0 Comment(s)
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This month we're bringing up the rear of our Tri-five chassis project with a host of cool new components for the rear suspension.

Assembling a vehicle (or, in the case of our "Framing a Classic" series, a chassis) is a lot like putting together a puzzle: You have to get a few pieces together before it begins to look like anything.

Well, we're happy to report that our Tri-five chassis project is quickly starting to look like something. That's because we've graduated from the "bare frame" stage by assembling a street-smart rear suspension using a variety of quality aftermarket components. And just like the pieces of a puzzle, choosing those parts was a matter of research and careful selection.

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Here's the foundation for the rear suspension-a 10-bolt rearend out of a '68 Camaro. It was an almost identical match width-wise (59 3/4-inches from axle flange to axle flange) to the original Tri-five rearend that we used for reference. We tore it down and cleaned it up prior to fitting the housing in the frame.

Take, for example, the rearend itself. Considering our outline for this project-to create a foundation for a contemporary street machine-we knew we wanted an updated rear axle assembly, one with better brakes, more gear choices, and a limited-slip unit. So we took some measurements off a stock '57 rearend and went looking for a suitable candidate. We found it in the form of an early Camaro 10-bolt housing. The Camaro unit had almost identical measurements to the Tri-five rearend-about 59 3/4-inches from axle flange to axle flange. Being a 10-bolt, we knew that parts availability would be good for it, and while it won't be quite as tough as a 12-bolt, it will be plenty strong for our needs while still being affordable.

Of course, any time you swap a rearend from one car to another, a little modification will be necessary. In the case of our Camaro 10-bolt, the width of the leaf spring pads was far from an exact match to our Tri-five's rear suspension. So after disassembling the rearend, we took it over to Williams Classic Chassis Works (the shop that's performing the work on our chassis) to have the old leaf spring pads cut off and a new pair welded on. Once that was handled, we headed down to DriveTrain Direct to have the rearend rebuilt.

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We selected these lowered leaf springs from Mike McGaughy's Classic Chevy to suspend the rearend. The new springs are designed to provide a 2 1/2-inch drop, which should be just about right for this classic cruiser.

After listening to the parameters of our project, the folks at DriveTrain Direct knew exactly which parts we needed for the rearend. They hooked us up with an Auburn Gear limited-slip unit, a gear set from Precision Gear (3.73:1 ratio), and a pair of high-strength Superior axles. They also supplied us with a complete rebuild kit containing all the bearings, races, shims, seals, and other small parts needed to make the rearend fresh again. With all of the new parts in order, DTD's Martin Barraza went to work assembling the 10-bolt, making sure that the pinion depth, backlash, gear contact pattern, and other vital specifications were all correct. (Highlights of the rearend assembly are covered in the sidebar, "10-Bolt Shuffle.")

With the rearend all geared up and ready to go, we turned our attention to the suspension. We knew from the start that we wanted to get our chassis in the weeds, and Mike McGaughy's Classic Chevy supplied us with the perfect starting point for that-lowered leaf springs. These de-arched leaf springs are designed to provide a 2 1/2-inch drop while still offering good ride quality. The drop is just what most Tri-fives need for a nice stance, especially when coupled with dropped spindles or other components designed to lower the front suspension.

Improved handling was another goal we'd set for our chassis, so we called up Performance Suspension Technology (PST) and ordered up a set of Polygraphite bushings for the leaf springs. Unlike rubber bushings, these graphite-impregnated polyurethane dampers don't deflect much when stressed, which will help keep the car from leaning excessively during hard cornering. PST also supplied us with a set of performance-oriented KYB Gas-A-Just shocks, plus a complete brake rebuild kit (featuring Metalli-Grip metallic linings) for the 10-bolt's drum brakes.

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