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We Upgrade the Subframe of a 1967-1974 Nova

Modern Nova: Fast-forwarding the Nova with a Detroit Speed subframe

John Ulaszek May 27, 2016
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While the 1968-’74 Nova rolled off the showroom floor with essentially the same suspension as the 1967-’69 Camaro, Camaros would be remembered as both drag and road racers, whereas the Nova is remembered mostly as a quarter-mile car. Forty years later, the chassis similarity is not lost on Nova enthusiasts, and Novas are increasingly tasked to not only run down the dragstrip, but around cones or a road course. Compared to the Camaro, 1968-’74 Novas were built for an additional four years, and thus are quite a bit more available and affordable while sharing almost entirely in the bounty of Camaro suspension and braking upgrades. Since our Nova project is starting with sheetmetal and not much else, we will spend more time putting it back together than taking it apart.

As Detroit Speed Inc. (DSE) had mini-tubbed our Nova, it was only natural to call them when it came time to upgrade our subframe with all new suspension, steering, and braking components.

Starting with nothing, our grocery list of parts started to add up quickly, and before long the total was pushing into a good percentage of the cost of a DSE subframe. We were pushed over the edge when we asked how the Nova would compare to a fifth-gen Camaro with equal power levels. According to DSE, the Nova would have no trouble keeping up or passing the Camaro.

While the additional cost of an entire subframe is a serious investment, it offers very serious returns in offsetting the cost and time involved in refurbishing the original, building in LSx integration, eliminating the need for some parts like hubs, supercar geometry specs, and upgrading the visual aspects that would not be attainable even on a highly modified stock subframe. As it would never be easier, we took the plunge and opted for the DSE subframe. For the purpose of this article, we also took the opportunity to pay a visit to DSE and have it assembled. To complement the capabilities of the subframe, we upgraded to Baer’s 6S Forged Monoblock brake system, which paired nicely with the C14 Forged Monoblock wheels from Complete Custom Wheel. We also upgraded the worn-out column shift steering column with a precise and good-looking piece from ididit.

Nova vs. Camaro Sheetmetal

While the Nova and Camaro chassis are nearly identical, the difference in sheetmetal generally favors the Camaro, especially the ’69. As a true “bolt-on,” the DSE subframe will absolutely maximize the potential of a Nova; not only making room for a wider rim and tire (9 inch vs. 8 inch), but making much better use of it. The subframe’s potential is actually held back by the Nova’s relatively cramped inner fender profile, as the exact same subframe mounted under a ’69 Camaro can easily swing a 10-inch-wide wheel, the only consolation is the ’67 and ’68 Camaro’s limited wheel width as well. Since DSE’s subframe has already increased the allowable wheel backspace to a very generous 6.125 inches, the wheels just can’t be tucked in any farther without reducing turning radius, so the inner fenders become the limit. In the case of our Nova, we are going to do a bit of fabrication and fender flaring to fit a 265mm tire on a 9.5-inch rim. Is the added work worth it for 10mm more tire? Probably not, but we can’t leave well enough alone, and it will certainly make us faster bench racers.

Compared to the Camaro, the Nova’s transmission tunnel is less spacious, which can limit the use of half-height body mounts, but we are going to do it anyway knowing we may have to cut the transmission tunnel to gain that extra half-inch of drop up front.

As the stock front subframe on a Nova is more visible behind the front wheels than a on Camaro, DSE’s low-profile framerails offer a surprising visual bonus, as it’s not obvious how chunky the stock framerails make the Nova look until it’s gone.

It’s important to note that no custom fabrication is needed to install the DSE subframe, but if you want to tinker, the factory sheetmetal will be your limit—not the subframe.

1 Detroit Speed Nova Subframe Upgrade 2/37

01. Surrounded by its various components, the subframe looks like a patient waiting for surgery; the assembly area is typical of the rest of DSE’s facility. Depending on your needs, DSE can offer the subframe unassembled and in bare metal, or for an extra $500 can powdercoat and assemble. If you choose bare metal, DSE will coat all metal surfaces with a corrosion-resistant coating, which is easily cleaned off with lacquer thinner.

2 Subframe Solidworks Design 3/37

02. The DSE subframe was designed and modeled in Solidworks with a clean sheet approach allowing it to mount up to a 10-inch-wide wheel with a 275mm tire while maintaining a 30-degree turning angle.

3 Hydroformed Framerail 4/37

03. The hydroformed framerail starts out as the pre-bent tube (on the left), which ultimately becomes the formed and laser cut part on the right. During the hydroforming process, the tube is clamped into tooling, and liquid at high pressure essentially pushes the tube outward until it meets the tooling at the same time, which allows the tube to shorten, which keeps the walls from stretching. Hydroforming also allows for lighter weight than a stamping of comparable stiffness, and complex shapes can be achieved with consistent wall thickness. Notice how the DSE framerail transitions from a vertical orientation to horizontal at the rear of the rail. The rear of the framerail is wider and shorter than the original, making the profile view of the Nova look much less “chunky,” as the framerail no longer hangs below the fender.

4 Tubular Control Arms 5/37

04. The tubular upper control arm has a radically different ball joint interface than the stamped-steel part it replaces, as the ball joint is now located on the top of the spindle entering the control arm through its machined steel ball joint socket. The arms themselves are fully TIG-welded and gusseted.

5 Dse Manufacturing 6/37

05. We couldn’t pass on an opportunity to check out DSE’s manufacturing facilities while we were on the premises. DSE co-owner Kyle Tucker inspects upper ball joint pockets as they drop out of the Haas machining center like a magical suspension gumball machine.

6 Dse Lower Control Arm 7/37

06. With its 1.5-inch diameter, 1010 DOM 1.20 wall steel tubing, and gusseting, the DSE lower control arm might look like overkill, it’s not. DSE’s testing found the arm needed to be this robust to prevent deflection under the higher cornering loads incurred by the wider tires the DSE subframe can support. Rubber bushings are replaced with greasable, Delrin bushings and thrust washers, eliminating the changes in geometry and non-linear spring rates resulting from the rubber bushing trying to handle thrust, radial loads, and isolation. Even a part seemingly as boring as the bumpstops were scrutinized, resulting in a custom design timed with suspension travel to limit the jounce travel in a controlled way.

7 Dse Non Adjustable Coilover 8/37

07. We chose the DSE non-adjustable coilover for its proven performance and simplicity. Double-adjustable and remote reservoir double-adjustables are available as well. All offer up to 1.5 inches of ride height adjustment and DSE-specific tuning. The springs are all supplied with a rate card, as they are 100-percent dyno tested. The coilovers also have a detent on the adjustment ring, allowing precise and repeatable changes in ride height.

8 C6 Corvette Spindle 9/37

08. While the presence of a C6 Corvette spindle might lead one to believe the DSE subframe simply copies the Vette’s suspension, that would be a mistake as the similarities end at the modified C6 part. DSE didn’t want the C6 steering arm to dictate rack placement or bumpsteer, so it was cut off and a new DSE-designed forged part was bolted on. C6 brakes can be directly bolted on with no additional cost for hubs as they are already installed.

9 Dse Steering Arms 10/37

09. Here, raw DSE steering arms forged from 4140 steel in America awaits finish machining. DSE’s steering arm design freed it to place the rack exactly where it needed to allow for optimal engine placement, drivetrain angle, and nearly eliminate bumpsteer (0.040-inches over 4 inches).

10 Splined Sway Bar Assembly 11/37

10. The splined sway bar assembly is more efficient than its OEM counterpart (top) as it swaps polyurethane bushings for Delrin bearings and is tightly constrained by the subframe crossmember. The splined bar is actuated by the steel arms, which are much stiffer than the sway bar, ensuring all the twisting happens in the sway bar—not in the compression of sway bar bushings. Sealed monoball endlinks provide the direct link of a Heim joint without the worry of wear and clunking.

11 Dse Rack 12/37

11. DSE targeted turning effort equivalent of a C6 Corvette and achieved a steering ratio of 12:1 using its custom steering arms. The rack provides for crisp wheel feedback with a carefully tuned dwell on center, preventing the driver from chasing every crack in the road when running wide, sticky tires up front. To achieve this goal, DSE’s ceramic-coated rack is filled with DSE-spec internals and is mounted with custom isolators.

12 Dse Labeled Subframe Products 13/37

12. For those opting to assemble the subframe themselves, DSE bags and clearly tags all hardware.

13 Lower Control Arm 14/37

13. Jay Lesar bolts in the lower control arm, which rotates smoothly on its Delrin bushings after torquing.

14 Upper Control Arm Mounts 15/37

14. The upper control arm mounts in much the same way as the original. Visually, this portion of the subframe will peek through the inner fenders, and to the uneducated eye will look like it might have come off the assembly line, although the stainless steel cross-shaft and tubular control arm will give it the look of a low-production exotic.

15 Shim Configuration 16/37

15. Because DSE holds tolerances so closely, this shim configuration will not only be good enough to drive the car to the alignment shop, it’s unlikely the shop will need to change it.

16 Coil Spring Framerail 17/37

16. On the original subframe, the coil spring is recessed into the framerail. The DSE coilover is mounted to the outside of the framerail, leaving the lock ring easily accessible for ride height adjustment. The subframe has an inherent drop of 2.5 inches with the coilovers offering up another 1.5 inches. The availability of which will be dictated by wheel choice, backspace, and the surrounding sheetmetal.

17 Steering Rack 18/37

17. The steering rack is mounted on DSE-spec isolators in double shear between the two subframe crossmembers, assuring steering input is not degraded by any deflection in the rack mounting configuration.

18 Dse Crossmember 19/37

18. Speaking of the DSE crossmember, its stamped design allows for large cross sections where it’s welded to the framerails and, using Photoshop, you can see how it’s internally braced to prevent deformation the stock crossmember typically suffers when used as a jacking point.

19 Upper Control Arm 20/37

19. Like the upper control arm alignment shims, this tie-rod adjustment should be extremely close to dead on at the alignment shop.

20 Moog Tie Rod Ball Joints 21/37

20. DSE exclusively uses Moog tie rod and ball joints, making it easy to install and remove the cotter pins.

21 Delrin Bushings 22/37

21. The splined-end sway bar is inserted into the front crossmember and supported by Delrin bushings. Machined bushings are welded into the crossmember, which is rigid enough to ensure the sway bar will be the only thing twisting.

22 Retaining Collars 23/37

22. The retaining collars constrain the movement of the sway bar.

23 Sway Bar Arms 24/37

23. The sway bar arms are installed vertically on both sides to ensure they are oriented identically, otherwise the endlinks will not line up properly.

24 Ball Joint Style Endlinks 25/37

24. With the modern ball joint-style endlinks tightened up, the modular sway bar assembly is direct acting, meaning the only deflection will be in the splined bar itself, assuring consistent behavior not possible in the original assemblies’ isolated endlinks and rubber bushings.

25 Chevrolet Nova Subframe Serialized 26/37

25. A DSE subframe is not complete until it’s tagged and serialized. Number 390 will go under our Nova.

26 Detroit Speed Subframe 27/37

26. The assembled DSE subframe comes in at about 50 pounds lighter than the assembly it replaces even though it’s substantially more rigid. In the end, DSE has designed and built a wholly new suspension making no compromises for suspension geometry or engine mounting configurations.

27 Stock Subframe 28/37

27. Back at the shop, the stock subframe is looking a bit sad. Given how inconsistently the original subframes are welded (this one was stitch-welded every few inches), they can’t compare in rigidity to the DSE hydroformed one-piece framerails. Notice how the original driver side framerail cross section is reduced behind the crossmember to make room for the steering box—the DSE subframe is substantially larger here. Surface rust aside, this is a solid and straight subframe. It could be worth several hundred dollars, which could help to offset some of the upgrade costs.

28 Subframe Centered Nova 29/37

28. Since most of the weight of the subframe is centered about the crossmembers, it balances nicely on a floor jack, making installation surprisingly easy for one person. It’s important to note that even a dead-stock Nova can have this subframe bolted in without any custom fabrication.

29 Dse Body Mounts 30/37

29. DSE body mounts will provide a more direct connection to the body than the rubber isolated factory mounts. While we will go back and cross measure the subframe to the rear suspension at a later date, the DSE-included factory alignment holes will suffice for rough fit.

30 Baer 6s Caliper Adapter 31/37

30. The Baer 6S caliper adapter bracket bolts directly to the DSE-modified spindle and converts to a radial mounting scheme.

31 Baer 14 Inch Rotor 32/37

31. Upgrade is probably not the right word to use when switching from tired, factory drum brakes to this massive Baer two-piece 14-inch rotor. The rotor slides onto the hubs without any drama and will provide a staggering performance and visual upgrade.

32 Baer 6s Caliper Monoblock Theme 33/37

32. The Baer 6S caliper’s monoblock design is forged from a single billet of aluminum, creating a work of art that is lighter and more rigid than it would be if bolted together. The caliper simply slips onto the previously assembled caliper bracket and comes loaded with Baer’s high-performance pads.

33 18 Inch Wheels 34/37

33. Keeping with the forged monoblock theme, we sourced anodized forged one-piece 18-inch wheels from ccwheel.com. Like the Baer 6S, this is made from a “near net” forging, which means the forged blank is very close to the finished part and requires relatively minimal machining, making for a very strong, lightweight part. It comes in at under 50 pounds total for the wheel and tire. On the left of the image, the low-profile rails of the subframe just barely peek out.

34 Motor Mount Kit 35/37

34. One of the intangible benefits of the DSE subframe is how it simplifies LS swaps with designed-in features that allow for oil pan and front accessory clearance. In addition to the LS engine’s weight reduction, this motor mount kit will set it back 1.5 inches closer to the firewall, allowing the car to turn better on the road course or launch harder at the dragstrip.

35 Ididit Steering Column 36/37

35. Considering how much effort DSE expended on its steering geometry and rack, a sloppy steering column would not do so we turned to ididit to swap out the Nova’s worn column for a new, American-made tilt model. Like the subframe, we opted for bare metal. The ididit column is a bolt-in for the Nova and will alleviate any worries about the nearly 40-year-old wiring.

36 Borgeson Universal Joints 37/37

36. To transfer steering input from the ididit column to the DSE rack, both ididit and DSE recommend Borgeson universal joints. The joint at the rack side also has a built-in isolator, which reduces noise, vibration, and harshness (NVH) without sacrificing crisp steering response.

Sources

Ididit
517-424-0577
www.ididit.com
Baer Racing
877-580-7272
www.baer.com
Detroit Speed
Mooresville, NC 28115
704-662-3272
www.detroitspeed.com

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