Tom Wilson
June 15, 2007
Adding the sublime-handling Griggs Racing Products GR40 suspension to the already sophisticated S197 Mustang puts it in danger of becoming a real car. The combination yields a gentle-riding, corner-carving road companion that will embarrass cars costing three times as much.

Horse Sense: Bruce Griggs' gear can make lions out of cats. We once sampled his 408ci Windsor-powered SN-95 with all the good suspension stuff at an open-track popu-lated by high-dollar European marques. Those wankers in the 930 turbos are still in therapy wondering how a Mustang could cruise around the outside of them, and we're sure the aggressively driven Corvette that spun off trying to keep up never told his friends.

When we first drove the '05 Mustang, we marveled at its chassis. Compared to earlier models, it was as if BMW had built it-such was the improvement in chassis rigidity and precision.

Another thought crossed our minds during those first S197 drives: This is a great Mustang. How much better can the chassis experts make it?

We just sampled the new Griggs Racing Products equipment for the S197, and the answer is plenty. The newest Mustang is a great car off the showroom floor, but it's still a mass-market automobile with all the safe understeer and cost-containment issues the term "mass market" implies. As is the company's style, Griggs has re-engineered the S197 Mustang suspension (mainly by replacing it), transforming the S197 into a no-compromises driving machine designed to thrill the most demanding and skilled among us.

On the S197 Mustang, it's the front suspension that needs all the work. Currently, Griggs offers only its up-market SLA frontend. It provides unreal precision and control in mid-corner-it's amazing to actually make minute corrections right through the corner apex.

Our drive in one of the first GR40-modified Mustangs, owned by Jeremy Grossman, was at Buttonwillow Raceway Park. The '05 GT carried the full gamut of Griggs suspension equipment and brakes for the S197, but it was otherwise stock. This combination of high-dollar SLA front and torque-arm rear suspension with a stock powertrain (sans cats) would be unlikely in a Fox or SN-95, but it doesn't seem unusual in the ever-evolving S197 market.

The drive was our typical race-pace sampling. As expected, the Griggs-modified S197 took to the track as if it had been born there, exhibiting the excitingly neutral handling and superb balance we've come to expect, but more so. Precision and bite were abundant, with newfound precision available right through the corner apex. The resulting speed from the stock powertrain was phenomenal. No stock 5.0 ever dreamed of such velocity with only a chassis under it.

This really was seductive speed, with the quiet exhaust, fully housebroken engine manners, stock interior, and so on. The car was buttery smooth and surprisingly supple, and it wasn't until we began reeling in some of the more powerful cars on track that we realized how fast we were lapping.

Peeking in from the front wheelwell, we can see the general layout of the coilover and twin A-arm system. As is everything else, the Griggs bumpsteer kit displayed prominently here is derived from the company's race cars.

We were also amazed to learn the Griggs S197 kits don't have any chassis reinforcement. While every Griggs suspension part is made of sterner stuff and is carefully designed to retain its shape under high loads, not a single brace is used. Ford's S197 chassis is that stiff. To a magazine staff raised on Mustangs with the rigidity of cooked spaghetti, this is an amazing development.

The only negative is the S197's weight. These new cars are hundreds of pounds heavier than previous Mustangs, which were built too lightly and require all sorts of heavy and expensive frame reinforcement before they dream of handling this well. In the Griggs-equipped S197, the weight manifests itself in what we at first swore was a lack of grip. Not bad, mind you, but the car slides wide as it reaches the limit. Then we understood the tires were simply being asked to contain 4,000 pounds of car and driver at such high speeds.

This is not to say the Griggs-equipped S197 felt heavy. It actually feels lighter than stock, thanks to weight reduction from the Griggs front crossmember, along with lighter steering from the more accurate, flatter suspension and steering geometry. It's just so accurate, balanced, secure, and easy to drive fast that the tire is the limit. Without a load of understeer to mask the front tire's response, it's much easier to drive the tire to its limit. Given the balance the Griggs gear gives the S197 chassis, the front and rear axles give up at nearly the same time, and voila, you might think the tires are lying down on the job.

Not unexpected, but worth mentioning, was the Griggs car plushness. The smooth ride is a Griggs characteristic, as Bruce Griggs wants suspension that actually travels; his cars invariably ride softly with only slight body roll.