1965 Oldsmobile Cutlass - Parking Lot Brawler - PHR Project Car
Our Newest Project Car Gets Ready To Dice Through The Autocross Cones With A Complete DSE Rear Suspension For '64-72 GM A-Bodies.
From the January, 2010 issue of Popular Hot Rodding
By Stephen Kim
Photography by Robert McGaffin
DSE offers its Rear Speed...
DSE offers its Rear Speed Kits for both '64-67 and '65-72 GM A-bodies. Speed Kit 1 (PN: 041603; $960) includes upper and lower control arms and chassis braces, while Speed Kit 2 (PN: 041607; $1,770) adds springs, a sway bar, and Koni shocks. Project Olds was fitted with DSE's Speed Kit 3 (PN: 041611; $2,345), which includes everything in Speed Kit 2 plus a set of custom-valved DSE alumium coilovers.
Avid readers will recognize the name Robert McGaffin as PHR's photographer extraordinaire. Squashing the competition like Walmart in what's left of capitalist America, Robert's endless assignments have brought him face-to-face with the hottest muscle cars featured in this magazine in recent years. Eventually, he couldn't bear standing on the sidelines any longer, and had to get a project car of his own. That itch has materialized in the form of a '65 Olds Cutlass, and he's determined to transform it into a pylon-clipping autocross beast.
The DSE kit can be installed...
The DSE kit can be installed with the rearend in the car, but with a lift at his disposal, Jarvis felt it was much easier to drop the entire assembly. The coilovers feature a new upper bracket that bolts to the frame, and removing the rearend improves access to this area of the car. After securely positioning the car on jackstands and disconnecting the stock control arms, shocks and brake lines, the rearend was lowered out of the way.
While shooting Randy Johnson's LS7-powered '66 Chevelle for our November 2008 issue, McGaffin contracted an A-body fetish that he couldn't shake. Disenchanted by the astronomical price tags affixed to the typical Chevelle, McGaffin realized a change of plan was in order. "I always wanted to build an A-body due to the availability of go-fast parts, and because they have plenty of room inside for my kids. Since Chevelles were so expensive, I started looking at Skylarks and Cutlasses and was amazed by how much more car you could get for the money," he recalls. "I've always been the guy who likes oddball stuff, and I liked the idea of building something that wasn't mainstream.
I found this '65 4-4-2 clone on eBay, struck up a deal for $7,500, and a few days later it was sitting in my garage. The car had already been restored in the past, so all the metal was solid and it needed no bodywork at all."
By opting for a not-so-common body that's attached to a very common platform, McGaffin essentially purchased a solid two-door post Cutlass for the same price as a jalopied-out Chevelle. That means he can focus less on restoration and more on performance. "My goal is to build something I can beat on around an autocross course that I can also take to cruise night and enjoy with my kids," he adds. "The stock 330 small-block is going to be replaced with a 500hp 455 big-block, and the suspension and brakes will be upgraded with hardware from DSE and Baer. Above all else, this car needs to be reliable, and I want to keep it on a reasonable budget." The best part is that you'll be able to read all about it right here in PHR as the project develops.
By far, the biggest challenge in building Project Olds will be getting a two-ton A-body to deftly negotiate tight autocross courses, and the big-block plopped up front will only compound the degree of difficulty. Consequently, it only makes sense to tackle the suspension first, and for guidance, we contacted Kyle Tucker at Detroit Speed and Engineering. Although best known for its cutting-edge suspension bits for first-gen F-bodies, DSE has recently expanded its product offerings to encompass GM A-bodies, X-bodies, and Chevy IIs as well. In light of our predicament, Tucker set us up with DSE's Rear Speed Kit, which includes a set of upper and lower control arms, coilovers, an adjustable sway bar, and a chassis brace kit. Lending a huge hand in the parts installation was Brent Jarvis of Performance Restorations in Mundelein, Illinois. Jarvis is no stranger to muscle car restorations, and he's done his fair share of competitively road race A-bodies. In the months ahead, we'll cover the build of Project Olds' engine, rearend, front suspension, fuel system, and brakes, but for now, here's how to transform your A-body's antiquated rear suspension into a laterally lethal combination.
|THE COST SO FAR
|'65 Olds Cutlass
|DSE four-link suspension
As with the upper control...
As with the upper control arms, the lower control arms were matched to the length of the stock arms for the initial installation. On A-bodies, Jarvis recommends setting the lower control arms at a 2- to 4-degree upward angle. "If you actually plot out the instant centers of the rear suspension, you will see that a slight upward angle will give you the best combination of front end lift and anti-dive characteristics. Lower is better to a point, but then the geometry gets screwed up and your suspension just won't work," he explains.
Adjusting the control arms...
Adjusting the control arms is as easy as shortening or lengthening the threaded portion of the arms, then locking down on the jamb nuts. Measuring from the center of one bolthole to the other provides the greatest accuracy when matching the length of the new control arms to the stock units.
Removing the upper control...
Removing the upper control arm bushings from the rearend housing can be a real bear. Jarvis says that using a hammer to either remove or install the bushings can crack the housing ears, so a press is a must, which resembles a big C-clamp. As expected of a 40-year-old car, the axle bearings were leaking, and the stock drums were removed accordingly to address the problem.
After removing decades worth...
After removing decades worth of grime off the rearend housing with a wire brush, it was given a fresh coat of paint. Before pressing in the new upper control arm bushings, which were supplied with DSE's kit, Jarvis made sure the openings were free of sharp edges and burrs that could potentially obstruct the bushings. A light coat of wheel bearing grease prevents distorting the bushings with excessive force from the press.
Perhaps the most innovative...
Perhaps the most innovative pieces bundled into the DSE kit are a set of chassis braces that attach between the upper and lower control arm brackets using the factory boltholes. This effectively triangulates the upper control arm mounts, rear crossmembers, and framerails to substantially stiffen one of the most severely stressed areas of the entire chassis. The braces were actually installed after the control arms were in place, but mocking them up beforehand shows how they're positioned in the chassis for illustrative purposes.
To reinforce the factory shock...
To reinforce the factory shock mount area and provide an attachment point for the aftermarket eyelet-style shock mounts, the DSE coilovers use a set of two-piece custom upper brackets. Before installing them, the factory shock mount holes must be enlarged to 3/8 inch.
The upper coilover bracket...
The upper coilover bracket is a two-piece design that sandwiches the framerail. Jarvis first placed the upper doubler plates on the top side of the chassis, then threaded a 3/8-inch bolt into them from the bottom side of the car using the outermost holes. In the two remaining holes, 3/8-inch capscrews were fed into the doubler plates and cinched down with Nylok nuts on top. All bolts were then torqued to 35 lb-ft.
The lower coilover conversion...
The lower coilover conversion bracket mounts to the lower control arm bracket with three bolts. Using existing holes on each lower control arm bracket, Jarvis attached the coilover bracket with 1/2-inch bolts and Nylok nuts. Next, using the coilover bracket as a template, two 5/16-inch holes were drilled into each factory bracket. With the mounting holes drilled, the coilover brackets were torqued to 25 lb-ft on the 5/16-inch bolts and 80 lb-ft on the 1/2-inch bolts.
Before reinstalling the rearend,...
Before reinstalling the rearend, the control arms and coilovers were attached finger-tight to the chassis side of the car. Getting everything to line up properly to their attachment points on the rearend can take some muscle, so it's helpful to leave some free play in the bolts.
With the control arms and...
With the control arms and coilovers attached to both the chassis and rearend, Jarvis torqued the bolts down to spec. DSE recommends using high-strength Loctite on the upper shock bolts, and tightening both ends to 70 lb-ft. The control arms require 110 lb-ft. While a spring rate of 150
lb/in might seem soft, it's important to remember that the stock Cutlass had no rear sway bar at all, and the addition of the DSE bar will increase roll stiffness dramatically. Furthermore, the A-body features springs that are mounted directly to the rearend housing, which yields an effective wheel rate that's identical to the spring rate. In cars where the springs are mounted in the control arms, the resulting linkage ratios create a wheel rate that's often far softer than the actual spring rate.
Although the final ride height...
Although the final ride height won't be dialed in until the front suspension is installed next month, Jarvis says it's important to set the baseline height as accurately as possible. He first threaded the coilover adjusting nut until he felt a slight amount of tension, then turned the nut three to four more rounds. Measuring between the base of the shock and the bottom of the adjusting nut with a caliper helps ensure that the left and right sides of the car are sitting evenly.
A-bodies use a triangulated...
A-bodies use a triangulated four-link, which eliminates the need for a Panhard bar. Consequently, the upper control arms are angled outward, which means that varying their length moves the rearend from side to side. With the tires reattached and the car back on the ground, Jarvis measured between the framerails and axle housing to help center the rearend perfectly.
In addition to determining...
In addition to determining the side-to-side positioning of the rearend, the orientation of the upper control arms also determines the pinion angle. From Jarvis' experience, 2 degrees of pinion angle provides plenty of forward bite for A-bodies, as their four-links don't distort much under heavy acceleration. To achieve that angle, he shortened the upper control arms slightly from their baseline setting.
Project Olds' new 275/40R18...
Project Olds' new 275/40R18 Nitto tires cleared the rear wheelwells, but just barely. Accurately centering the rearend helps maximize the available real estate in the stock tubs. Jarvis plans to set the cornerweights during final suspension setup, but for now, the rear ride height was set at 23.5 inches from the ground to the top of the wheelwell.
With the new control arms,...
With the new control arms, braces, and coilovers in place, it was time to install DSE's 1.125-inch tubular rear sway bar. Unlike many factory bars that attach to the lower control arms, the DSE piece bolts to the frame. This keeps more vertical load on the inside wheel during cornering for enhanced grip. Since the preliminary ride height had already been set, Jarvis mocked the sway bar into position to help determine where the frame would have to be drilled for the endlink mounts. The bar was affixed to the rearend using supplied U-bolts torqued to 60 lb-ft.
The DSE endlinks swivel back...
The DSE endlinks swivel back and forth along two axis, which allows the sway bar to articulate freely and reduces binding. The upper and lower endlink bolts were tightened to 45 and 40 lb-ft, respectively. The sway bar features two mounting points, which enables fine tuning the rear end stiffness. The distance separating the two holes might not seem like much, but the basic tenets of sway bar design say that minimal changes in swing arm length yield dramatic changes in bar stiffness. DSE rates the bar stiffness at 507 lb/in when the front mounting holes are used, and 624 lb/in when the rear holes are used.
Using DSE's provided template,...
Using DSE's provided template, Jarvis drilled two 1/2-inch holes in the rear crossmember, each spaced 15.5 inches from the crossmember centerline. The endlink brackets were then affixed to the frame using 1/2-inch bolts and Nylok nuts torqued to 80 lb-ft.