5.0 Mustang & Super Fords
Autocross Suspension Upgrades - Crossing The Line
Learn the Basics of Suspension Modification
Credit Ricardo Topete of GTR Performance for the idea. A longtime dealer of Maximum Motorsports suspension parts, Ricardo, along with his brother-in-business Gonzalo, asked us if we'd be interested in doing a bolt-on suspension story. Instead of the usual step-by-step documentation, why not skip the installation and concentrate instead on what the parts do for you?
A great idea that gets right to the heart of what the average guy can expect from suspension modifications. To keep things in the real world we agreed to attend a local autocross where the Topete brothers could bolt-on a series of popular suspension parts from handling specialist Maximum Motorsports and Eibach. Items tested were alignment settings, Maximum's lowering springs, Panhard bar, an Eibach rear sway bar and shock settings. On hand, but not tested because a day is only so long were the matching Eibach front sway bar and Maximum rear lower control arms.
Just as real-world as running out of time is the test car, Ricardo's '01 Mustang GT daily driver. Before the test Ricardo re-installed his stock springs and set the car to stock alignment so it would represent the typical project car starting point. Under the hood the internally stock 4.6 was augmented by its long-installed Novi 1000 supercharger plus a smattering of performance knick-knacks, none of which materially affected our handling exercise. More to the point, the stock five-speed gearbox and 3.27 gearing remained intact and '00 Mustang Cobra R brakes by Brembo tabled any stopping concerns.
To speed the test, Ricardo pre-installed the Maximum Motorsports adjustable Panhard bar, then removed the bar itself. That allowed fitting the bar to the car in just a few minutes at the track. Alignment settings were pre-checked, and the car was already equipped with Maximum Motorsports caster/camber plates and adjustable Tokico shocks, so those adjustments were easy to do trackside as well. As for the lowering springs, the SN-95 and New Edge use non-concentric spring/shock package, making spring changes relatively easy, especially for Ricardo who has popped more than his share of coils in and out of Mustangs.
Suspension testing requires the maximum available grip from the tires. Old or low-traction tires will slip and slide no matter what suspension they are bolted to. Good traction is a must for suspension improvements to show, so we turned to Nitto for a set of NT01s, and that was the end of any traction questions. After years of happy experience with NT01s, we can reliably report these street-legal road racing tires are great for track-driven Mustangs thanks to excellent grip, a linear breakaway at the limit, and a reasonably durable wear rate.
So, how did the pieces do? In a word, great. On a slalom course that took most cars present about 1:42 seconds to lap we opened in the 1:41 to 1:42 range and finished the day with consistent low 1:39s. That's a big jump, not to mention the tremendous gain in responsiveness and overall stability.
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From a seat-of-the-Levi's perspective, the two items making the big differences were the lowering springs and the rear sway bar. The springs gave the Mustang a solidity and responsiveness that could be felt driving in the paddock. On track they transformed the car from a somewhat sloppy street car into a reasonably taut performer that could be driven both more precisely and with more aggression.
The rear sway bar did wonders for reducing understeer. By increasing rear roll stiffness, the rear bar transferred some of the cornering loads from the front to the rear tires, allowing the front tires to bite harder and better balance the Mustang's inherent nose-heaviness. To a lesser extent, dialing in more negative camber using the caster/camber plates reduced understeer as well. Also keep in mind the lowering springs also gained us a much-needed degree of negative camber, so simply stiffer spring rates and a lower ride height weren't all of the lowering springs advantages.