The GR40 Mustang Experience

Although the S197 Mustangs are a huge improvement over their predecessors, their limitations remain, designed to keep average drivers cocooned. Understeer is, if not grinding, excessive to the enthusiast. Precision is leagues better but hardly ideal, the rear axle hops when driven hard and the whole thing is too heavy. Furthermore, as power is significantly increased with superchargers and such, the compromises in the stock suspension are made more apparent. So, while the S197 Mustangs do well making the meek feel sporty, they still need significant help before they are sporting.

As we investigated the new Mustang, we were thrilled to find a highly rigid—if heavy—chassis, and disappointed to encounter weaknesses in the spindle, ball joint and K-member. They dashed any hope of lightly modifying the car up to Griggs standards, resulting in a new set of highly developed A-arm front suspension parts that are lighter, stronger, more durable and far more precise. In the rear Ford’s 3-link suspension needs corrective measures when lowered, and is best replaced by our proven torque arm system for the ultimate in axle control and traction. The bright spot is the unibody; thanks to Ford’s stiff chassis there is no need for supplemental reinforcements such as subframe connectors, saving money, time and weight.
Transformed with a full Griggs suspension, the result is simply stunning. The GR40 suspended S197 Mustang graduates into a real sports car; a delightful, precise companion in the curves. Building on Ford’s new found chassis rigidity, the Griggs SLA front and torque arm rear GR40 suspension puts feel in the steering and delivers front end grip that has to driven to be believed. The car points into the corner with enthusiasm and carves right down to the apex with a light, precise, linear feel to the steering. This authority is even more appreciated in mid-corner, the place where the stock steering goes vague and responds slowly and unevenly. Here the GR40 front suspension, its tires flatly planted to the asphalt, answers with immediate, precise corrections. It’s a revelation to anyone experiencing the joy of piloting a precise, spirited chassis for the first time, or to the old hand who didn’t expect such excellence from a heavy powerhouse such as the Mustang.

Squeeze on the power and the GR40 answers with torque-arm traction, the bite that handles both huge torque and yet remains precise to the throttle. And bumps? They soak into the rear suspension and stay there while the tires remain on the ground. This is one confidence inspiring suspension; you can stand on the gas and the rear tires will claw the car forward while the supple front end takes care of directional duties without fuss.

Also unexpected is the incredibly civil ride from the GR40 suspension. It feels as plush as the stock suspension, and in the bumps when trying hard, even more so. The combination of stiff chassis and accurate, correct GR40 suspension geometry means we can let the wheels move up and down, which in turn delivers a ride that’ll please the fussiest daily commuter.
If the GR40 system has a fault on the S197 it’s that it works so well you’ll want more from the tires. The car tracks so honestly right up to the limit, and has such gentle manners as the tires sign off that you’ll be ready for more grip. It’s that good.

I must also mention the 4on4 brakes. Besides reducing unsprung weight, these brakes offer a new level of precision in the brake pedal. This is especially true in the brake release, an area where stock brakes are absolute dullards. The 4on4 brakes let go of the discs with the same sensitivity they apply them; on open track day that means slowly coming off the brake in perfect confidence while the tail end –so expertly controlled by the GR40 gear—rotates magnificently outward as much or as little as you wish. The transition from threshold braking to the throttle while holding the car at the limit has never been so rewarding.

So yes, the S197 Mustang is a huge step forward by Ford, and the GR40 suspension delivers the full promise of this greatest of all Mustangs