Hello all,
I am a regular AutoCrosser as well a participate in all DE events run by the MetroNY PCA region. Many people ask me about suspensions and suspension setup, here is some info I have gathered...

For AutoCrossing and DE's especially, the goal is to keep the car as flat as possible under all circumstances. Think of a car going around a curve. As you take a right hand curve, all the weight is transfered to the outside wheel, this is obvious. However, by unloading the inside wheel, you will loose all its traction ability. Eventhough the outside wheel will have an increased traction ability due to the weight transfer, the almost complete loss of weight on the inside wheel will overcome any gains in traction of the outside wheel. The result: a car with much less overall traction and thus cornering power.

How do we fix this situation? Run a stiffer suspension and larger diameter anti-roll bars (commonly mis-named "anti-sway bars"). What will this achieve? This will counter the weight transfer of the car to some degree, as well as its negative effects. Don't misunderstand though, weight will still transfer from side to side, however, the car will not lean as much and thus the inside wheel will not be lightened (and lifted) as much as before. This will cause more weight to remain on the inside wheel then before, increasing its traction and thus cornering power. The outside wheel will still benefit from increased weight, traction, and cornering power too. The difference being, since this weight is more evenly spread over the car side to side, the OVERALL traction the car will develope will be increased and the overall cornering power will be higher. A good thing!!

Here are the suspensions I have experience with for a fully race-preped 2002 Carrera 4 Cabriolet

Stock US Suspension: The car was spongier then a Cadillac. Horrible handling characteristics. The car understeers extremely badly, turn-in was dull and mushy, and the car was upset under hard braking due to the nearly 4 to 5" (!!!!!) of nose dive!!!!!!

RoW M030: This suspension is a slightly stiffer version of the stock suspension. Though a big step up over stock US suspension, for the hardcore track and AutoCross enthusiast, it leaves much to be desired. I have had limited experience with it, but, from what little experience I have I can say this: you will still have body roll, the car still rides way to high, and there will still be dive and squat under braking and accelerating, however, all those things will be reduced as compared to the stock US suspension.

X74 Suspension: This seems to be the best suspension for the all-around street/track/race car (if such a thing truely exists). This suspension is billed by Porsche as the "GT3 Suspension for non-GT3 cars". I have had it on the car for about 3 months now, and have raced on it 3 times. Let me tell you, it is fantastic, I feel as though I have a brand new car. The changes were drastic. After about a month and a half of settling, the car dropped about 60mm all around, a big difference. This will not only help in terms of looks, what most are striving for, but aerodynamically as well. By limiting the total amount of airflow under the car, we can assure that no lift will be produced. This will become apparent when speeding down the main straight of Pocono at 140 to 160mph. Even in a straight line, the car feel much more planted then it ever did with the stock suspension. This, I would presume, is due to that lowered ride height.

Rake is also increased with this suspension. Rake is defined as the front to rear difference in ride height. In other words, the nose being a bit lower then the rear. An increase in rake means the nose is even more lowered when compared to the tail. This increase in static rake, aerodynamically, allows the car to be much more efficient. By presenting this slightly different forward aspect to the oncoming wind, the car will produce even less lift, infact, we might even get a tad bit of downforce, though probably not too much if any. The aerodynamics of the car are mainly intended on creating 0 lift, there is no way for us to create the 5000lbs of downforce an F1 car does.

In terms of handling, wow! The car has almost 0 body roll, dive or squat. As we discussed before, this is what we are after, a flat car. Now, obviously we will not be as flat as a Cup Car, however, you can't drive a Cup Car on the street, you can drive an X74 car though! With a good alignment (-1.5° negative camber front / -2.5° negative camber rear), the car will be perfectly neutral. Turnin is lightening fast and sharp as a tack. The car is no longer upset in braking as there is very little dive. The biggest benefit though is cornering. With a good set of tires, Hoosiers or Pilot Sport Cups, the car will stick like glue.

In addition, everything is much more progressive and easy to feel, always a positive. Before, with the stock suspension, on turn in, it would take a few milliseconds for the sloppy, soft suspension to catch up. This is known as the car "falling over itself". The easiest way to describe this is as follows: turn the wheel, and you feel the car rock back and forth as the springs compress and rebound. NOT GOOD!!! I am probably not explaining the sensation very well as I don't know how, but, to those of you who have experienced this, you know it will yield an unpredictable car in turnin and midcorner untill the suspension "takes a set". Now, with the X74, the car doesn't fall over itself at all. Turnin is instantaneous and extremely predictable. It is much easier to give it a bit more throttle, kick the *** out and slide around that corner for that added ounce of excitment! Midcorner unsteadiness is cured and bumpsteer drastically reduced.

All in all, I feel for the street/race car, the X74 suspension is the way to go. I have had nothing but good things to say about it as compared to stock. I feel my driving experiences are much more enjoyable as well. Now, I would like to close by saying these are only my impressions of the suspension and that information I have found while researching it. I have no experience with H&R Coilovers, PSS9s, or a full, all out Cup Car with a fully adjustable remote reservoir suspension system, thus I can not compare the X74 to them. I hope this information has helped some.

If anyone has any questions regarding suspensions or their setup, please feel free to ask...

Happy racing!!!

Jonathan Landon