The circle for the most complete Pro Touring car draws tighter by the day and Chris and Lynda Jacobs’ ’66 Chevelle is proof positive. Chassis builders dedicated to the genre went from adjustable shocks, tubular suspension members, frame connectors, and the stiffening agent of a rollcage, to complete front and rear subframe assemblies and enlarged tubs to house the biggest available tire and wheel combinations, and now to complete perimeter frames, including suspension members. The latest and the greatest development is the inclusion of a bulletproof independent rear suspension system.
On smooth, uninterrupted tarmac the solid rear axle has traditionally been considered the best for this type of work. But on the vagaries of public roads and a sometimes crumbling infrastructure, smooth becomes a relative term. The best-handling road cars have always included an independent rear suspension for its ability to absorb irregularities per wheel and not transfer the oscillation to the one opposite, thus centering the vehicle better and keeping tire tread in constant contact with the road surface.
Let’s keep in mind that Pro Touring cars are meant to be street driven. The idea is that you actually drive them to the venue and back home again. They aren’t queens; they’re workhorses that transport you to cruise night, on sightseeing trips, and maybe the occasional street bash on the way back from the supermarket. They’re meant to be lived in. Well, the Jacobses have taken their car several steps beyond.
Chris: “Our Chevelle has almost every feature you would find on a new Camaro or Mustang: keyless entry system and leather seats to power windows, A/C, and cupholders, too. Besides all of this it handles just as good if not better [than a Mustang or Camaro], gets 24 mpg on the highway at 80 with air on and makes more than 500 hp at the wheels. Does it get any better?”
This writer remembers a mid-’80s Pontiac long-led introduction that featured engineering toys, one of which was a Trans Am with an independent rear suspension system. I drove the production car over a circuitous mountain road and then switched seats and took the same route. I was astounded at how much more controllable the IRS car was and how smooth its ride was, a truly remarkable transformation that I can still feel beneath me.
Chris concurs: “That’s where the new chassis shines, is on the street. The car now feels much more solid and the ride is fantastic. While at Des Moines [Goodguys autocross Street Machine winner Heartland Nationals, 2011] we had to compete against much more purpose-built cars and still walked away with a victory … I had the second fastest time of the event.” Chris said that he’d only had two weeks on the testing and adjustments.
The first part of this saga began with a 283 ’Glide Malibu out of Colorado, rescued by Randy Johnson of D&Z Customs in Kewaskum, Wisconsin. Johnson settled in a Schwartz Extreme Performance chassis, added a tweaked LS7, bolted a T56 behind it, and followed up with a Johnson’s third member/axle. Chris and Johnson became friends and eventually the car belonged to Chris. That was in 2008.
In the winter of 2010, Chris took the car to the Roadster Shop (RS) in Mundelein, Illinois, just for some exhaust work. So happened, RS was looking for an A-body to prototype another version of its new Fast Track IRS chassis. The conversion included a perimeter frame, tubular suspension members, and an independent rear suspension system. Since then, “True Blue” has become the RS A-body development vehicle.
Chris: “The fact that [the Chevelle] is so understated in its appearance but is so technically advanced … is what makes the car so great.” Can’t argue with that.
The interior must be as mature and developed as the mechanicals. In its first incarnation, D&Z applied Cerullo SC seats. Ace Upholstery in West Bend, Indiana, fitted them in leather and repeated the treatment on the bench. All the Stewart-Warner Maximum Performance dials and ancillary switches were logically arranged in a frugal but elegant Rocky Mountain Dashes panel, and offset by Vintage Air Gen IV air ducts. Speartech Engineering in Anderson, Indiana, provided the wiring harness and the engine controller. The Limited Edition quick-release steering wheel is from NRG Innovations in City of Industry, California. While wheeling the 24-mpg Chevelle down the interstate, the Jacobses synchronize souls with an Alpine head unit, Focal front speakers (in custom kick panels) and two 10-inch Focal subwoofers driven by an Audio Art 340-watt amplifier. They are strapped by Corbeau harnesses and belts and have immediate access to the custom center console and its array of control switches and aluminum cupholders. Programmable fobs provide exterior control of the windows, door locks, and remote security system.
In the search for a well-balanced machine and a chassis that could use every bit of torque and horsepower that the engine produced, D&Z obtained an LS7 (one of 30 or so) originally built by the GM Race Group for a project that was later aborted. Modifications were scant but pertinent. The cast pistons were replaced with Mahle 11.0:1 forgings and the cylinder heads are still completely stock. A Finish Line Performance/COMP Cams hydraulic roller (0.635/0.660-inch lift, 231/243 degrees duration) bumps LS7 pushrods, COMP springs (retainers, seals, and valve locks), and OE rocker arms tweaked by Wegner Performance. Factory LS7 injectors and mass air sensor are preceded by a 90mm throttle body hooked to custom air intake tube. Fuel comes from a custom Rick’s stainless cell and submersed 255-gph Walbro pump. Cooling is provided by a big Be Cool core and fan assembly. Standard LS7 coil packs fire the mix. Integrity of the oiling system is founded on a Peterson Fluid Systems 9-quart tank and the original Corvette bat-wing sump. Contaminants are voided through Dynatech stainless headers to Borla XR1 race muffs and a 3-inch diameter stainless Roadster Shop to-the-bumper exhaust tract. Rear-wheel output is a tidy 467 lb-ft at 5,122 rpm and 514 hp at 6,393 rpm. The drivetrain was a bolt-up: LS7 clutch assembly, modified Rockland gear Son of Tranzilla T56 (2.66, 1.78, 1.30, 1.00, 0.74, and 0.50:1) manipulated by a Pro 5.0 shifter, Coleman aluminum driveshaft, aluminum 9-inch Ford centersection with a high-zoot Wavetrac differential and 4.11:1 gears.
Wheels & Brakes
Rather than falling for the usual multi-bolt modular indigenous to prime Pro Touring examples, Chris envisioned something different: spoked Weld RT-S 74s, 18x9.5 in front and 18x12 wides in the back that are complemented by de rigueur Michelin PS-2 tires in 275/35 and 335/30 configurations. Energy burners are Wilwood six-piston Superlite 13-inch and four-piston 13-inch, respectively.
The Chevelle needed quarter-panels and a new SS hood, but the rest of the factory sheetmetal just needed to be curried, combed, and straightened by D&Z. They stretched the wheeltubs 3 inches, smoothed the firewall, sanded the floors, and painted the underside in satin black. Randy Johnson created and positioned the tasteful minimal air spoiler. From the guns at Midwest Muscle Car Restoration in Slinger, Wisconsin, came the PPG Chevrolet Mist Blue.
Undoubtedly the highlight of the build, the IRS undercarriage extends to the outermost regions of the body shell. The structure is web-like and some of its structural runners extend far beneath the Chevelle, ensuring torsional and bending stiffness that no other construction could. The rigidity it imparts is quiet enough to preclude a rollcage that would normally be required for such support. Car weight is a hefty 3,740 pounds now, but still lighter than the original combo, which was at 3,850. The Fast Track frame is imbued with ’11 C6 Corvette spindles and hubs, nearly vertical AFCO PT Elite double-adjustable dampers fitted with 450-lb/in coil springs, and a Roadster Shop splined antisway bar. At the other end, Roadster installed its IRS composed of a Ford 9-inch aluminum chunk mounted in a steel cradle assembly. The cradle also serves as the mounting for the upper and lower control arms as well as a splined track bar. AFCO Elites mimic the front setup but employ 500-lb/in coils. Remote reservoirs attend both the front and the rear assemblies. RS retained the original 15:1 AGR steering rack. CHP