I got an e-mail from the Praxis people saying the EVO was on the "short list" for next years product developmet. I know its expensive, but it seems like almost the perfect solution for a street/track car. If you even think you might be intrested please let them know on their survey. Follow the survey link on this page


Some cut and paste for those not familiar with the system. It has gotten extremely good reviews in the mags.

Praxis is the first aftermarket suspension that has been professionally engineered to consider all tunable elements of the suspension system. Springs, dampers, bushings, tires, suspension alignment, and suspension geometry have been considered to optimize performance over a wide range of operating environments. Praxis has leveraged Bridgestone technology to bring design and development tools previously available only to automobile manufacturers, to produce a revolutionary air suspension for the motorsports enthusiast. Long gone are the days of trial-and-error parts matching and aftermarket modifications that compromise everyday drivability.

Praxis allows the driver to select the height, spring-rate, and damping for whatever driving adventure lies ahead. There are no coil springs to change or spanners to carry, because the spring-rate and ride-height are controlled by air. It’s as easy as touching a button and turning a knob. Select one of three programmed ride-heights and spring-rates with a simple push of a cockpit mounted button. Then adjust damping by turning the adjuster that is conveniently located on each strut unit … you control the level of performance.

the suspension ecu also corner weights the car automaticly, very cool.

 

We currenlty carry this system for the WRX and BMW 3 series. Its pretty cool really.



Aside from the EVO, theres also talk of a Honda system as well. Theres three settings:

Touring mode provides ride height, ride characteristics and handling traits that are comparable to the vehicle's original suspension. This mode provides the most comfortable ride qualities for weekday commuting, weekend touring and long vacation trips. This mode also preserves the vehicle's original ground clearance to enhance its mobility when driven through deep snow or on secondary roads.

Sport mode reduces vehicle ride height by 25 millimeters from the Touring mode ride height and increases spring and shock damping rates to reduce body motions and sharpen steering response. This mode provides a more aggressive appearance along with sportier ride characteristics and more responsive handling traits than the vehicle's original suspension for fun, enthusiastic driving on twisting roads.

Track mode reduces vehicle ride height by 50 millimeters from the Touring mode ride height, virtually doubles the original spring rate and specifies the firmest shock damping rates to maximize stability and handling response. This ultimate performance mode provides the most aggressive appearance along with performance for autocross and track driving situations. The no-nonsense Track mode is not recommended for street driving or the faint of heart.

The systems run around $4K depending on the vehicle. I really dont know how much the EVO kit will run when it comes out. You can read more about this system on our website here:

Praxis Adaptive Performance Suspension System

and all of its system components in detail here;

Praxis Adaptive Performance Suspension Components

 

Not looking for an argument, but some data-log info and actual tests (reviews) will be appreciated BEFORE I spend money on Praxis System for the Evo.

Quote from Sport Compact Car mag - Sept 2004: Project Evo vs. Project STi (page 192-194.)

..."The most telling result of this test was how different the STi and the Evo felt. The Evo's brake pedal was always firm and consistent, the steering precise and the tyres forgiving. The STi, in comparison, was terrifying. The thousands of dollars of suspension work we've done to the STi have delivered test numbers fairly close to the Evo's (.97g vs. the Evo's .99g, and 71 mph in the slalom vs. the Evo's 73.4), but the true handling envelope is nowhere near the same.... We had the Praxis suspension set in its medium height Sport mode where it's stiffer but still has travel, but the car was still far too sensitive to bumps. It's possible that's in part because of the extra spring rate from the very-stiff Hotchkis anti-roll bars, but we suspect it's inherent in the Praxis system"....

Please clarify about different setup specs that would CORRECT these characteristics. I would hate to build my Evo and "screw up" the handling; especially with expensive parts.

 

The Praxis approach is interesting, but I have always thought that there is a fundamental problem - wheel alignment change with ride height. There is a change in camber and toe at both ends of the car when you drop it 50 mm. Praxis seems to "solve" this by having a compromise alignment that works to some extent at all ride heights, but is not ideal for any. Or maybe it is ideal for the center setting, I'm not sure. In any case, there is compromise.

 

Nix, the secont part of the quote explains their problem. Siffer spring rates need less roll stiffness. In my experience, huge roll bars and very stiff spring rates do not go well together.

Tsi, everything is a compromise. I track my car and I'd like to have it 50mm lower with much stiffer springs, however I am not really wanting to make the compromise in ride quality. From what I have seen of the praxis the alignment ends up being optimum for cornering in the track mode, while the other modes give up some max cornering ability in exchange for a setting that wont wear out the inside of the tires. Seems like something I could live with.