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Performance Front Subframe and Suspension Swap - Makeover!
After A Couple Of False Starts, We Get Serious About Our '73 Camaro
Jan 1, 2010
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Performance Front Subframe and Suspension Swap - Makeover!
Detroit Speed's subframes are standard in bare steel and unassembled. We opted to have ours powdercoated satin black and delivered with Detroit Speed's rack-and-pinion unit installed. Note the large aluminum spacers and bushings that locate the rack close to the engine cradle for proper steering geometry. Of note; each DSE subframe has a unique serial number on its data plate.
The beefy tubular lower control arms are gusseted and crossbraced for strength, and revised geometry that includes additional positive caster and a lowered spring pocket. The nut should be roughly 21/4 inches from the end of the threads.
Rather than the polyurethane bushings found in many suspension kits, DSE opted for stiff Delrin bushings with steel housings and crush tubes that won't deflect under load.
Though this may change later when we dial the car in, we initially installed two shims per bolt on the upper control arms. While the arm is mild steel, the cross-shaft is stainless steel for strength and corrosion resistance.
The revised geometry of the upper control arms was aimed specifically at increasing camber gain versus stock and improving roll camber. Note the grease fittings; some say Delrin bushings don't need lubrication, but DSE recommends it.
The upper eyelet of the coilover mounts with Grade 8 hardware and a bushing. Make sure the bushing is properly oriented to center the coilover in the pocket.
Our coilovers are the standard aluminum body units that allow ride height adjustment and feature proprietary valving developed through track testing. They're not adjustable, but walk the line nicely between handling performance and ride quality. Three different standard springs rates are available: 475 in-lb for small-blocks, 525 in-lb for big-blocks, and 425 in-lb for LS engines.
Here's the big reason for all the suspension changes; the DSE subframe is designed around stock C6 Corvette spindles which helped engineers get the caster, camber, and toe curves the way they wanted-plus the added benefit of easily sourced performance brake kits and never needing to repack bearings during brake jobs.
DSE carries the full line of Baer Pro-Plus systems and recommended the 6P calipers with the 14-inch rotor upgrade since it's designed for outstanding performance on the track as well as the day-to-day stop-and-go. We also like that the calipers utilize off-the-shelf C5 and C6 Corvette pads.
Making the significantly dissimilar spindle and rack communicate like they were designed for the same car is accomplished via Detroit Speed's unique modified steering knuckles that provide an excellent turning radius-something lacking in a few rack-and-pinion retrofits.
Rather than standard style endlinks that sandwich the sway bar arm between bushings, DSE uses these aluminum pieces also sourced from C6 Vettes since they offer a much more precise transfer of motion. The ball joints are Moog equipment.
Here's one of the other huge benefits of the DSE subframe; an integrated 11/4-inch splined sway bar. A properly installed three-piece sway bar eliminates the binding and flex inherent in standard one-piece style bars. Inside the retaining clamp is a Delrin bushing. Though DSE doesn't offer upgrades, serious racers could slide in different diameter bars with custom bushings to tune the suspension for various tracks and car weights.
The thick sway bar arms won't have any unintended deflection. As such, the bar itself doesn't have to be as stiff to keep the car flat through a turn.
The DSE suspension package allows for up to a 10-inch-wide wheel without modification to the inner wheelwells, so we opted for killer 18x10 Livewire rollers from Rushforth Wheels. All wheels are custom built to your specifications and include a number of options ranging from 17- to 24-inch diameters with your choice of 7- to 15-inch widths. You can also personalize the finish with a full polish or opt between a powdercoated look with or without the perimeter hardware. After a lengthy conversation with Jason Rushforth himself, we went with the brushed-aluminum finish with polished wheel lips, which made for a rather stunning combination. Our rubber of choice included a set of performance oriented P275/35ZR18 g-Force T/A KDW 2's
Before removing the stock subframe, we've got some measuring to do. With the car on jack stands, we dropped a plumb bob from the mounting bolt of the lower control arm.
Once we established the point, we marked an X on the floor with a paint pen. Precision counts here since as little as 1/16 of an inch can throw the suspension geometry off.
Next, we dropped the plumb bob from the mounting bolt of the rear leaf-spring pocket and marked it as well. Taking careful measurements, we were pleased and surprised to find that Project F73 was fairly straight with only 1/8 inch of variation from side to side.
After that, just a few zips of the air ratchet removed the four mounting bolts for the subframe.
Though they share a similar shape, a nose-to-nose comparison shows some of the key improvements over the factory design that DSE incorporated into their subframe and suspension. Despite being significantly more rigid, the DSE-exclusive hydroformed framerails actually have a thinner O.D. The additional crossmember that mounts the rack and sway bar also serves to stiffen the front of the frame.
Overall, the rails are notably more consistent in form and lack the pinches and seams of the original. Note the multiple transmission crossmember mount options.
Forget rubber or urethane bushings, to eliminate the inevitable flexing between the subframe and body DSE uses solid- aluminum bushings and stainless steel bolts. Whether you use DSE equipment or not, this upgrade is a must for those serious about handling.
With a floor jack placed under the main crossmember, the subframe actually balances quite well. With a buddy's help it's easy to position it and get the body mounts in place. Everything stays loose for now though since we've got more measuring to do.
Since the lower control arm mount location has moved, our original Xs weren't any help in centering the subframe so we dropped the plumb bob again to find our points.
Here you can see how far off the marks really are. These measurements are extra critical, so don't be afraid to take your time since side-to-side variations of 1/16 of an inch or less are considered acceptable.
Believe it or not, without much effort we were exactly 1/16 of an inch different from side to side. Who says there aren't any straight Camaros left out there?
With a little custom modification by A&E Motorsports, we'll be hooking up our steering with a Flaming River steering shaft. This really needs to done before the engine is installed since accessibility will be very tight afterwards.
We've still got plenty of plumbing ahead of us for the brakes and rack-and-pinion, but we now essentially have the front suspension wrapped up. Next, we'll move on to the rear.
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Read all about the new front subframe and suspension system we swap in on our 1973 Chevy Camaro. Only at www.chevyhiperformance.com, the official website for Chevy High Performance Magazine!
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