PRAXIS Suspension systems – Three Distinct Suspensions, One Car

Let’s face it–folks like us like our cars quick and tight. And although we want the very best straight from the factory, that’s often not good enough–we like to tweak every aspect of our rides for optimal performance. Problem is, we have to use our cars for more than just one purpose, and the best tune for a day at the track might not cut it for an afternoon running errands.

In to this quandary steps Bridgestone, and their new PRAXIS air suspension system. Aimed squarely at the performance-driving enthusiast, the PRAXIS setup allows for a single suspension system to work optimally in any conditions–and to be entirely adjustable from the driver’s seat. Ride height, spring rate, and suspension stiffness are adjustable to any of three predetermined settings: Touring, which is comparable to the OEM suspension in height and softness; Sport, which lowers the car 25mm and ups the responsiveness of the springs and dampers considerably, for a spirited drive on public roads; and Track, the firmest setting, in which the car is lowered a full 50mm, spring rates are doubled, and responsiveness and road feel are optimal for racing situations. Bridgestone claims the settings for the Track mode are tuned and set at the famed Nurburgring.

How it works is this: essentially, your car’s entire suspension (front struts, rear dampers, and coil springs) are replaced with a sophisticated air-spring setup and adjustable dampers. The system is controlled by a PRAXIS-specific ECU unit, which is constantly reading information from an accelerometer and four height sensors. This processor adjusts air flow to individual corners of the car, to adjust for various cornering loads instantly. An on-board compressor provides pressure to meet the various need of the springs, as determined by the computer. All wiring and tubing is of course provided, and a user interface, installed in the cockpit, provides the driver instant control over the suspension settings. The control unit mounts anywhere the driver wishes, and allows instantaneous switching between suspension settings with the simple turn of a knob.

Currently, the PRAXIS system is available for two of the most popularly tuned performance cars on our streets today–the BMW 3-Series (1999-2004 E-46 models, including the M3, coupe, convertible, sedan and wagon, with any engine) and Subaru Impreza, WRX and STi (2002-2004). The system is individually designed for these applications, so installation does not require any evil cutting or welding, and can be accomplished by a person with moderate mechanical skills. Bridgestone promises more PRAXIS applications will be available soon.

We tested the system at the Poconos International Raceway on both vehicles, and found it to be nothing short of amazing. All three settings are distinctly different, as promised. The Touring mode really does feel like the factory setup in the BMW; in the WRX STi we tested, we’d say it was even more responsive, although more than comfortable enough for street use. The Sport mode is what we would likely use as a default; the lower ride height is sexy, and the increased road feel is impressive. In Track mode, the cars felt like entirely different machines–very stiff, but certainly appropriate for real racing use. We came away impressed (and hoping Bridgestone would send us a test kit for one of our personal rides…).

Bridgestone says PRAXIS is the first aftermarket suspension system that combines all tunable aspects of a vehicle’s suspension. While your average tuner can buy components from any of several suppliers and mix-and-match a custom system, it’s not easy to integrate a tuned suspension when you springs come from a different source than your shocks, which are in turn made by different people than the engineers who designed your anti-sway bar, etc. PRAXIS not only eliminates all that guesswork, but it eliminates the need for compromise in an aftermarket suspension between drivability in day-to-day conditions and perfect track handling. Since it’s all engineered from the factory to work in concert, and has three distinct settings, the PRAXIS system is essentially the only suspension investment–beyond wheels and tires–that a tuner should ever need.

At a cost of $3,995 for the entire system (for the BMW), plus approximately 8-10 hours of labor, PRAXIS is not for the average driver–but it’s a real boon if you vary your driving conditions considerably–and certainly a lot cheaper (and easier!) than buying three separate suspension systems for your car. Having driven the system in it’s natural environment, we can say it works just as they say it does–although we’d not turn down a long-term test of the product!

For additional details, a list of authorized distributors, and to check on upcoming applications, visit the website.

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