1967 Chevy Chevy II - I Did It My Way

Can an average guy build a high-tech 1g suspension in his driveway? Here's the story of one reader who tried.

By John Parsons

Photography by John Parsons, John Ulaszek

My '67 Chevy II project, called II Much, was at a crossroad. I wasn't happy with how the car was turning out: Instead of the ultimate g-Machine I had envisioned, my car was beginning to resemble a cool late-model "street rod." My original budget of $30K was shredded just buying tools, and my original schedule was in ruins as I taught myself how to weld, run a mill and bend sheet metal. My shop and garage are littered with my "automotive art collection," parts I had spent significant time making, but ultimately discarded as I learned how to make them better. A few of them hang on the wall mocking me as I remind myself that I am having fun.

I had just finished welding an aftermarket chassis and rollcage into the car. I had also made my own firewall, floor, trunk and wheel wells to go with the chassis and cage. The car body was done. The LS1 and T56 were over in the corner waiting patiently to do their stuff. Paint it, bolt it together, wire it, and drive it. My Chevy II could be running by the end of the year.

My first impression of the front suspension components of my aftermarket chassis was that I had to do more. I originally bought this particular chassis because their Mustang II offering was the best-handling front suspension I could find, but now that wasn't good enough for me. I wanted this Chevy II to really handle where I planned on racing it-Summit Point Raceway in neighboring West Virginia. Not only do they have an awesome two-mile road course, but also they've got a skid pad where I planned on making lateral g measurements. Based on this, I came to the conclusion that the street rod suspension had to go.

Since I was using custom frame rails, there wasn't an aftermarket offering I could use. And while I didn't have the experience to design a new suspension, I knew someone who did. My friend Katz Tsubai is an actual suspension designer. Katz agreed to take on the project if I would give him a clean sheet of paper: no factory spindles or control arms. He said we would need to make all of our own parts. That's where my friend Brian Schein comes in. Brian is a professional machinist and quickly signed up to make parts and welding jigs. I can't remember what I promised him to help me, but it worked.

Katz began design work in early 2003. We went through countless design iterations, working through tire and wheel combinations and figuring out what rack might work. Finally, we realized a custom rack was needed. I contacted Tony Woodward and walked him though our design and plan. Tony made some geometry suggestions and I ordered up a custom rack and had it sent to Katz. The next problem was that the aftermarket frame rails were not designed to work with a 9-inch wheel and a 265 tire. More design work followed and I ending up with notches in the frame and fender flanges lying on the garage floor. Now the car will have a turning diameter less than 45 feet, so I can make U-turns and drive through parking lots.

Late in 2003, Brian began designing the welding jigs for the control arms. During the coldest day of the year (late January 2004) with a foot of snow on the ground, I drove up to Brian's crowded unheated shop. After an all-night session I took home the jigs and the parts to weld together. Brian began designing the machine jigs for the aluminum uprights. I also contacted another friend, Glenn Estelle, to do a finite element analysis of the upright to see if 7075 aluminum would hold up: aluminum work hardens over time, so a cyclic analysis needed to be done. In the meantime, another friend, Rick Klein, cast some stainless steel uprights for me in case the aluminum didn't pass the FEA test. Ultimately, they did, though barely. The stainless uprights are now in my art collection.

Winter came and went and spring began. I welded in the new crossmember after taking countless measurements. I should have taken countless-plus-one measurements: I fully welded the crossmember exactly one-inch too far forward on the frame rails. Katz tried to bail me out, but could only tweak the design to get 0.25 inch back. As a result, the wheelbase of the car is now 0.75-inch longer. I finished up all the welding of the control arms and mounting points and Brian made steady progress on the uprights. Then Katz found some errors in the ball joint assumptions and we had to make some last-minute changes to the control arms. Finally, months behind schedule, the parts were done. We made nearly every part of the suspension ourselves. The only parts I actually bought were the ball joints (three different times), shocks and springs, rod ends and steering rack. Even the C4 hubs had to be machined to fit properly. If my ride breaks down in the middle of nowhere, I'll be flat-bedding the car home. No visits to the local auto parts store for me.

I'm going to show you what we came up with, as well as show you some of the theory behind the parts. Even if you decide you aren't going to cut your car down to frame rails and build a new suspension from chunks of aluminum and chrome moly, a lot of what you read here can be applied to selecting aftermarket suspension pieces, like control arms or spindles. Read on and learn more about what makes front suspensions work. And, if you're insane like me, grab your welding helmet.

First, what was wrong with the original front suspension? The old suspension was Mustang-II based and while Mustang II front suspensions are everywhere, it isn't because of their great handling. It is efficient packaging and good strength that make them attractive for street rod frames and aftermarket clips. With one cross member, two upper control arm mounts, beefy spindles, and plenty of spring rate, an experienced chassis builder can install one in a couple of days. Installation ease aside, they suffer from little camber gain, very low roll center, dynamic roll center movement, and a small suspension sweet spot. It was designed for a low-cost economy car, not for turning in at 120 mph.

So how does someone go from an empty sheet of paper to a working suspension? Katz designs suspensions from the outside in, so we started with the tires: Pirelli 265/30R18 PZero Corsas and Kinesis K28 18x9 wheels, with 7-3/8-inch backspacing. We established their position, factored in the brake rotors (Wilwood 14-inch SRPs), wheel hubs (C4) and then placed the lower control arm mounting point and lower ball joint. With the "bottom" of the geometry located, he worked up to allow the tallest possible spindle (see why the tires and rims have to be chosen first?) and then over to complete the upper control arm.

By utilizing a large-diameter wheel with lots of backspacing, the new suspension is able to use longer control arms, taller spindles, and has a bigger sweet spot. "Good" geometry for handling means just enough camber gain to counteract body roll, a roll center optimized with springs and sway bar, minimal side scrub and a small scrub radius. The short (25-inch tall) tires are just reality in my Chevy II platform. I was not going to stretch the wheel wells, or relieve the fenders and a 25-inch tire is all that could be crammed under the car and still have sufficient wheel travel with a reasonable turning radius.

Establishing all of these pickup points sounds hard, but there is help available. In the days of slide rules and Brylcream, engineers would make mockup parts from wood and clay. Today, we have computer-aided design tools. Katz's tool of choice is WinGeo, which is designed for professional use with a price to match. You can accomplish much of the same thing with less expensive software, such as that offered by Performance Trends. Different geometries can be quickly fed in and their resulting behavior studied.

Once we were satisfied with our basic geometry, secondary design elements had to be solved such as shock mounts, cross member fabrication, steering ratio and rack and pinion placement. Shock mounts have to be symmetrical and the cross member has to support mounting of the lower control arms and the rack. The placement of the rack to minimize bumpsteer is critical: not only do we need to be mindful of tie-rod angles and pivot points, but there are usually things in the way like harmonic balancers and oil pans.

All the design steps were iterated many times. We even iterated on the design as we were making parts. Check out the photos to see how it all came together. Was it all worth countless hours, sleepless nights and a 15-month delay in the completion of II Much? Only time will tell.

Now I'm eyeing my four-link rear suspension. The front suspension design has out-classed it and Katz tells me we can make a nice three-link setup (similar to the new Mustang) in no time. I think those old rear link arms will look good in my art collection.