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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PST supplied us with parts that should help this chassis handle (once a car is put on top of it, that is). They included Polygraphite leaf spring bushings and a set of KYB Gas-A-Just shocks.

In addition to handling the corners, we wanted a little extra help in straight lines. We got it with a set of tubular traction bars from Williams. Like all traction bars, these are designed to prevent the rear axle housing from twisting upward when the car is launched from a stop. But unlike "slapper" style bars, the Williams units attach to the leaf springs (via the U-bolts) and the frame for a more solid mounting configuration. They feature bushings on both ends, and a threaded rod end on one side so you can tailor the fit to your car (bars with adjustable ends on both sides are available for those seeking more precise preload control).

And finally, keeping in mind that our project started out as a bare '55 Chevy frame, there are a lot of small "peripheral" parts that we're going to need as assembly continues. Fortunately, the Danchuk Manufacturing catalog is chock full of such items. For this story, Danchuk provided us with leaf spring shackles and shock mount plates. These small-but-significant parts were just what we needed to bolt everything together.

Speaking of putting everything together, we handed all the parts over to the Williams Classic crew (Earle Williams, Larry Garrett, and Jeff Howe) for assembly. Installation was pretty straightforward, although a lot of care and attention to detail was required while mocking the rearend in place and welding the new spring pads on the housing. Follow along with the photos and you'll get an idea of how it was all done.

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After pressing new bearings onto the pinion gear (plus new bearing races and a pinion seal into the differential case)...

10-Bolt Shuffle
So how do you turn a garden-variety rearend into something worthy of performance street duty? We asked the folks at DriveTrain Direct that question, and they responded by building us a top-notch 10-bolt.

The resulting rearend wasn't filled with exotic components, just a carefully selected assortment of quality aftermarket parts. It started with an Auburn Gear limited-slip unit to aid us in the traction department. That was accompanied by a 3.73:1 ring-and-pinion set from Precision Gear. New axle shafts from Superior Axle and Gear were also part of the package. The axles offer a lot more strength than stock units because they're made with larger-diameter shafts, a better grade of alloy, and rolled splines. The parts were assembled by Martin Barraza using one of DriveTrain Direct's overhaul kits, which contain all the bearings, races, shims, seals, and other small components needed to complete the rearend.

While we don't have the space to show and tell you everything you need to know to rebuild a rearend at home, we can walk you through the highlights of our 10-bolt rebuild. Martin made it all look easy, but you should realize that he has thousands of rebuilds under his belt. If you're inexperienced in this arena, we strongly suggest not trying this at home. Of course, if you do know what you're doing, DriveTrain Direct can supply you with all the parts you need to assemble a stout rearend. They can also rebuild your rearend for you, or sell you one of the many rebuilt assemblies that they have in stock.

Sources

Performance Suspension Technology
Montville, NJ 07045
877-226-4101
www.p-s-t.com
Precision Gear
Suwanee, GA 30024
800-449-6649
http://www.precisiongear.com
Williams Classic Chassis Works
La Verne, CA 91750
Danchuk Manufacturing
Santa Ana, CA 92705
Drive Train Direct
Rancho Santa Margarita, CA 92688

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We bring up the rear of our '55 Chevy chassis with a 10-Bolt rearend, lowered leaf springs, and traction bars
Damon Lee Jun 1, 2000

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