The name Roadster Shop is synonymous with pushing the envelope when it comes to building cars and designing the parts that go into them. The goal of Phil and Jeremy Gerber's family-owned business has always been to ride the razor-sharp cutting edge of hot-rodding, and once again they've managed to do it without cutting themselves.
Seeing that all of the world's modern sports cars have for decades had independent rear suspensions (IRS), the Gerbers knew they had to find a way to install an IRS in their already popular solid-axle Chevelle chassis. Since their '64-67 A-body rolling skeleton was undergoing design changes to allow for tighter fitment to the body, it was the logical first choice for their IRS experiment. The end result is that now all Roadster Shop '64-67 A-body chassis can be ordered either with a conventional solid axle or the new IRS.
The initial R&D took about six months. Thorough research of caster/camber roll curves, suspension geometry, and other NASA-level math resulted in an IRS that not only performs as well as anything coming from Europe, but has the added wow factor to get people on their hands and knees at shows and events.
At the same time all this development was going on, Chris and Lynda Jacobs had brought their immaculate '66 Chevelle in for a skeletal transplant of its own. The car was originally going to have the Roadster Shop's standard chassis installed, but when Chris saw the new IRS system taking shape, he made a beeline for Phil's office to get one for himself. Never one to miss an opportunity, Phil decided that the Jacob's car would be the perfect vehicle for the first Roadster Shop IRS to hit the road. It was also the car the company brought to our fourth-annual Super Chevy Suspension & Handling Challenge, presented by Nitto Tire.
Driving Impression - On The Autocross Course
Of all the cars that attacked this year's Handling Challenge autocross course, the Roadster Shop's entry, Chris and Linda Jacobs' Chevelle, brought handling and performance to an entirely new level. Sporting their fully adjustable and specifically manufactured independent rear suspension, it was quickly apparent this car had absolutely no holes. It had it all, the LS7 aluminum 427 with huge power and torque, tires that gave me incredible grip and feedback, smooth-shifting transmission, predictable brakes that were up to the task of stopping this 3,800lb car, and most excellent steering quality. Add to that some gorgeous looks, and it doesn't get much better than this. Man, I love my job!
To ensure the cars had the opportunity to do their best, the participants had a go or ten on the autocross course the day before our Challenge to dial in their suspensions. When I drove the Roadster Shop Chevelle, the initial feel was one of being locked in place and way too rigid for the horsepower and tire. We (myself and Roadster Shop head honcho Phil Gerber) discussed what I felt and agreed to make changes to get the suspension working better and more compliant. Softer, my friends, softer.
After a couple of hours adjusting things, Phil presented me with something just this side of automotive nirvana. He rode shotgun, and heading to the initial five-cone slalom, I knew this car was an entirely different animal. I had grip, the Chevelle went where it was pointed, there was the ability to trail-brake and rotate this huge mass of metal, and I'm feeling warm and fuzzy. Rounding the far end, I asked what they'd done, and laughingly was told, "I can't tell you; it's a secret!"
For the official timed runs, I knew this car was going to be fast, and drove it accordingly. Planting my foot as best I dared with the LS7, I used left foot braking to move the Chevelle through the initial slalom and out to the offsets. What was cool about this car were the manual brakes. They were very linear, and all this Chevelle needed was a light application to slow for an element's entry speed and nothing more. Want to slow the cavalry down a bunch? Just press down on that stopper pedal a little more. All brakes should be this good. Using those binders late at the end turnaround got me rotated and positioned so nice for corner exit. The '66 felt solid and united; I could move it where I wanted, and I'm grinning ear-to-ear.
Headed back, the "Chicago Box" part of the autocross posed no issues, and the Chevelle easily threaded itself through. For those not fluent in autocross course lingo, a "Chicago Box" is a three-sided box with a lane of cones splitting the open section. Think of it like a very tight single cone slalom. And yes, it showed up at one of the Solo Nationals in--where else--Chicago. This element is very high risk due to the sea of two-second time penalties staring you down through the windshield. But when done right, you can brake in a straight line, turn, and then burn like mad out and onwards.
And textbook it was. I was deep into Second gear, braking planted the nose entering the "Box," and approaching the center "turn" cone, I lifted. The Chevelle rotated, and when almost straight we got out and headed for home. No car felt as balanced and joined together as this one did. Going by feel, I was fairly positive the Chevelle took fastest autocross time. It did. --.
Driving Impression - On The Street
As a knuckle-dragging quarter-mile racer who likes to go around a road course just as much (if not more), I often roll my eyes when people espouse the virtues of an independent rear. Sure, the ride quality can be better, but too many people use IRS as an excuse to over-spring a vehicle, thus erasing any ride quality benefit on the street. Plus, modern technology has allowed solid-axle cars to accomplish amazing levels of grip on track, while not sacrificing strip reliability.
One 20-minute ride in the Roadster Shop Chevelle had me rethinking my previous mindset. Now, I can't vouch for its performance on the strip with slicks bolted on, but goodness, this car was remarkable in street driving. From my logbook: "It rides like a new car. No vices, no surprises. It's smooth and stable."
It seemed impossible to upset the suspension. Aiming for divots in the road on the way out of the AMCI Test Center barely registered from my Cirillo seat. Railroad tracks? What railroad tracks? The steering found that often elusive sweet spot between fast and too fast. It was just right. My only gripes were a shifter that was too far forward and a steering wheel that was very close to my chest.
The 13-inch, six-piston front and 13-inch, four-piston rear brakes had this car stopping with no drama. They were a little noisy, but the pedal feel was excellent, both direct and linear. The 630-horse LS7 and stock Z06 clutch and trans are a match made in hot-rod heaven.
Comparing the instrumented test numbers, the Roadster Shop had it all over the factory Camaro. It was .80 mph faster through the slalom and an unreal 10.22 seconds quicker through the autocross. Are you kidding me or what?
Adding the IRS option when you order your Chevelle chassis will cause the bottom line to balloon by $7,995--more with upgrades like more robust axles or a sway bar, but if you really plan on driving your A-body hard after it's finished, we have no qualms about recommending you spend the extra bucks. --
Roadster Shop '66 Chevelle
EngineType: LS7 427ci
Fuel Delivery: GM fuel injection
Transmission: Rockland Tranzilla six-speed
Clutch: GM from a Z06 Corvette
Rearend: 9-inch, 4.10 gears, Wave-Track differential
Chassis: Roadster Shop Fast Track
Front Suspension: Roadster Shop upper and lower tubular A-arms
Steering: Rack-and-pinion 15:1 ratio
Springs: 450 lbs/in
Spindles: GM C6 Corvette
Shocks: AFCO PT Elite double-adjustable coilovers with remote reservoir
Sway Bar: 1.25 OD x 0.0990-wall splined
Brakes: Wilwood six-piston calipers and 13-inch rotors
Rear Suspension: Roadster Shop Fast Track IRS
Springs: 500 lbs/in
Shocks: AFCO PT Elite double-adjustable coilovers with remote reservoir
Sway Bar: Roadster Shop 1.25-OD x 0.0990-wall splined
Brakes: Wilwood four-piston calipers and 13-inch rotors
Total Cost of Chassis and Suspension: $25,480
Wheels & Tires
Wheels: Weld RT-574, front-18x9.5, rear-18x12
Tires: Michelin Pilot Sports, front-275/35R18, rear- 335/30R18
|LF= 921 lbs||RF= 905 lbs|
|LR= 957 lbs||RR= 994 lbs|
|F= 48.4||R= 51.6|
Slalom 48.5 MPH (average of the best 5 runs)
Autocross 43.06 Sec. (Best lap)
2010 Chevy Camaro SS
Slalom 47.70 mph
Autocross 53.28 sec.