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Chevy II Renovation, Part II - 1966 Chevy Nova Rear Suspension

Completing our Box Nova Heidt's Suspension Transformation

Photography by John Nelson

It's been a few months since we began our Chevy II renovation, and the time has finally come to complete this project and put our Heidt's-suspended guinea pig to the test. Our quest to totally transform the launching, handling, and braking abilities of a '66 Nova began with "Chevy II Renovation, Part I" in the Super Chevy Sept. '05 issue. In that first installment we performed "radical bolt-on surgery" by fitting our box Nova with a Heidt's Superide II IFS front subframe. Besides paring 150 pounds off the car's nose, the stout steel box-tubing structure gave us greater strength, as well as rack-and-pinion steering, coilover shocks, and Wilwood four-piston brakes. Most importantly, though, is the fact that the new system provides modern suspension geometry, a necessary update for optimum ride and handling qualities. In this, the second and final part of our Chevy II Renovation, we'll complete the suspension transformation by installing Heidt's Complete Nova Rear Subframe, then hit the test track to measure our improvement.

The Heidt's rear subframe kit includes a top crossmember (or shockbar), subframe connectors, a Panhard bar, coilovers, and four-links with axle brackets. Options include polished four-links and a Panhard bar, chrome coilovers, an adjustable trans mount, and axle housings with the brackets installed. We chose all these options, and Heidt's also sent along a set of 31-spline axles and Wilwood rear disc brakes to complement our front binders. Bolt-in kits are available, but Heidt's recommends the weld-in variety for race cars. Thinking to the future, we chose the weld-in version.

There are many benefits to this setup, strength and stiffness foremost among them. Adding Heidt's box-section steel subframe connectors stiffens the Nova's original stamped-steel flexi-flyer subframe, improving stability and laying the foundation for the improved suspension setup. The stock leaf-spring/shock arrangement is replaced with a tunable four-link system and coilovers. Traction, and therefore launching ability, is vastly improved with the four-link setup. "You get a firmer, more solid launch compared to the leaf springs," Gary Heidt told us. "The subframe connectors also have a lot to do with that," he added. We knew the four-link would give us better launches at the strip. But when it comes to making overall improvements to the Nova's ride and handling characteristics, Heidt pointed elsewhere. "The Panhard bar determines the car's roll axis," he explained to us. "When this roll center is low compared to the front of the car," he continued, "you get more understeer, which gives the driver more control. You're then in a nice, drivable car." And that's exactly what we ended up with.

Johns Customz & Performance in Torrance, California, again performed installation duties for this project, and set the veteran Chevy II up for its "after" day at the track. Before we get to that, here's some more info on our particular setup. First of all, we went with BFGoodrich Traction T/A tires, 215/60HR60 all the way around. These tires carry a good "AA" traction rating and a sky-high wear rating of 440. What does it all mean? This is good rubber, but not sticky, canyon-carving material, which would have a traction rating in the 300s. In other words, we went with real-world tires that will work well on the street and last awhile. The suspension setup echoed this ideal. Out back, six turns of the spring collars made the Nova's control arms parallel with the ground. Up front, three turns did the trick, while the damping adjustment on the Aldan coilovers was set right in the middle. Rather than using a one-off "track day" setup, we went with a street-going configuration.

The results, as you can see by our measurements, are impressive. We'll take them one by one. First, although the Nova's engine remained untouched, we did stiffen its rear gearing, going with 3.70:1 cogs rather than the old 3.08:1 set. This change, however, certainly doesn't account for a 0.54-second e.t. improvement. The Nova was easier to launch hard, and also tracked much straighter than before, without a hint of fishtailing. Up front, the new rack has none of the vagueness found in the stock steering box. With drag radials in place, we think 13s are within reach.

The improvement in braking was even more impressive. We cut a full 41 feet off our 60-0-mph distance, and fade was virtually eliminated. With g-machine-type rubber, there may have been another 15 feet or so to be had. Besides the great improvement in performance, this Nova's safety factor has been wildly increased. On the skidpad, we again saw a great improvement, picking up a full point and almost pulling 0.80g. With some suspension adjustment and the aforementioned turn-and-burn rubber, we would have easily broken into this area. The increase in turning ability was borne out on the slalom course, as we picked up a full 5 mph through the cones. More importantly, perhaps, is the improved feel of the car. With its stock suspension (but on the same tires), turning hard was an all-or-nothing proposition: turn hard enough and the back end would slide. With the full Heidt's setup, the Nova gained an entirely new feel. The driver has a "gray area" while turning and can work closer to the tires' edge without worrying about oversteer. And with all that, the ol' Chevy II just plain drives better under normal conditions. Nice.

The bottom line is, we like it when a plan comes together. John Barbera of Johns Customz is very familiar with this car and told us he thinks the improvement is "fantastic." Besides saying the car "handles, goes straight, and is safe," John made one astute observation when he said the driver now "knows where the car is at all times." It's a fitting statement. We've gained performance in all areas, but also control. It's a good place to be in. The Heidt's suspension we installed on this '66 Nova works, and the potential for even greater performance is there. Check out the pics to see how this box finally booked.

BY THE NUMBERS
 Before After
1/4-mile 14.74 at 94.06 mph14.25 at 99.12 mph
Braking (60-0 mph)200 feet159 feet
Skidpad0.66g0.76g
600-ft. slalom52.99 mph58.03 mph

Sources

BFGoodrich Tires
www.bfgoodrich.com
or visit your local BFG dealer

Driveline Service
16539-1/2 S. Broadway, Dept. SC
Gardena, CA 90248
(310) 515-2860

Heidt's Hot Rod Shop
111 Kerry Ln., Dept. SC
Wauconda, IL 60084
(800) 841-8188
www.heidts.com

Johns Customz & Performance
20022 S. Normandie Ave., Dept. SC
Torrance, CA 90502
(310) 808-0005
www.johnscoustomz.com

Miller Electric Manufacturing Co.
1635 W. Spencer St., P.O. Box 1079, Dept. SC
Appleton, WI 54912
(920) 734-9821
www.millerwelds.com

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