Improving a Pony Car's Handling – Part 1: Suspension Adjustability on a Budget
By Vince Illi
Apparently I’m weird. (I just told you something you didn’t already know, right?) MotoIQ people think I’m nuts for driving a domestic vehicle with too many cylinders under the hood. Fellow Mustang owners think I’m nuts for racing my car around corners. Road Racers think I’m nuts for dodging cones in parking lots and calling it “autocross” instead of a “driver’s license exam.”
When Ford released the latest Mustang chassis (code S197) in late 2004, they finally turned the Mustang into a world-class sports car platform. Gone was a pathetic chassis based on the old Fox Body that possessed rigidity paralleled only by moist balsa wood. It was replaced by a far more rigid structure with a good front suspension modeled closely on the 3-Series BMW’s. The GT’s weight bias is 54% front, which is pretty dang good for having a massive V8 up front. Sure, it still has a live rear axle, but the fact that the latest factory-tuned BOSS 302 kept up with and beat BMW’s M3 around Laguna Seca shows that beam axles can still be competitive around corners.
Being the weirdo that I am, I bought my Mustang for two purposes: daily driver and autocross terror. From the factory, the car is setup very well. It handles much better than its depleted-uranium 3,600-pound mass should. But, alas, my pony-car/land-yacht must compete with Miatas and S2000s half its size. It certainly has the advantage in power, but it tends to understeer after the apex of a corner. As an example, in a constant-radius corner, I would have to increase the steering input after the apex to keep the car on my intended line. My slip angle was increasing post-apex. The limited-slip differential installed from the factory helped me compensate somewhat by increasing throttle input a little early and powering out of the corner. But still, I felt I could do more.
In an earlier article, I installed forged wheels and stickier tires. While greatly improving handling and lateral grip, it did little to allay the post-apex understeering and did nothing at all for the body roll.
After perusing Mr. Kojima’s Ultimate Guide to Suspension and Handling, I decided on my path ahead to improve the handling. I figured taming the body roll and eliminating that post-apex understeering would be the first thing I should do after getting those stickier tires.
The first thing I tried was a strut-tower brace. Cars with the factory Brembo brake package came with a strut-tower brace from the factory. Although strut-tower braces are thought by many people to do nothing other than add weight, I thought I’d give one a try. I reasoned that some Ford engineer thought they were effective enough to convince the bean-counters to include them on Brembo-equipped cars.
|Not really much to a strut-tower brace, but the Steeda piece is lightweight (under 9 pounds), well-constructed, and looks fairly nice under the hood.|
To that end, I called up Steeda and ordered their strut-tower brace. After bolting it on, I noticed a slight improvement in initial turn-in and a more “solid” feeling around road imperfections, but it did absolutely nothing for the body roll or post-apex understeer. I needed a more complete solution.
Now, this being MotoIQ, I know what everyone’s thinking: KW coilovers and Whiteline sway bars and bushings! Unfortunately, I’m still making payments on my V8 lead sled and have no sponsors, unless you include Mom baking me cookies. (She says I’m special!) While I would have definitely liked a set of KW coilovers, I realized a few things. First of all, KW’s Variant 3s and clubsports lower my vehicle by a minimum of 1.5 inches. The S197 chassis cannot be lowered any further than that without compromising the suspension geometry and requiring additional parts, so using the coilovers for further height adjustment was out. Setting compression on your damper is nice for fine tuning, but I could do without that since I’m still a noob. I really wanted adjustable rebound, though. Koni shocks to the rescue!