Subaru vs Mitsubishi MAP 2012 Event at BIR

Not really possible outside of active suspension (i.e. ferrofluid dampers tied to an electronic system). For performance you will always trade away comfort. The amount of comfort you must give away for something actually competent on asphalt is sizable. You will end up with a very different car. You will get used to it, but there's a big change. For example, I run 350 lb/in front and 250 lb/in rear springs. I run the car in the middle of the strut range of travel, near 16" fender to wheel center. This is a compromise setup for both auto-x and rally-x. This setup is what I consider far from daily comfortable yet still not something that is totally dedicated to asphalt use with a sticky pair of tires. You can get away with a softer setup, but you are sacrificing things doing so. For a real asphalt car, you need a pretty stiff setup. I'm 30% stiffer than a STI, but I still consider it soft for on-road use. I want to be stiffer yet for auto-x because it is useful, and I'm still not on slicks.

So what's the best mix?

Well, I will suggest a damper with high low speed damping but mild high speed damping (chassis control + impact compliance), high spring rates (springs themselves don't actually add much harshness), and use a setup that has moderate suspension travel. Most of the harshness you can generate first comes from bottoming out the car. Adequate travel is number one. The second greatest source of harshness is high speed damping resistance. You can run a kinked profile to limit the force transmitted to the chassis. Beyond that, I don't much consider many things to be offensive. I like stiff bushings, firm ride, and all that. The only other thing that really annoys is a bouncy ride because high speed oscillation is annoying. However, excellent low speed damping will help control this.

 

Thanks for the info, learning new things everyday! Sounds like a good set up, I don't think I need much as far as high speed, as I don't plan on doing much faster then the speed limit unless I'm at the track.

 

By low and high speed damping, I don't mean car speed. I mean motion speed of the damper. The faster the damper goes, the more resistance there is. Some dampers are linear like the stock struts, AGX, and D-Spec. Slow to fast, they offer the same percentage of damping. Some dampers are non-linear and run a damping profile that is kinked. The kink can go both ways depending on the valving. Koni is a good example of this. They have a slight rise in low speed damping versus higher speed damping (a hump before tapering off gently). Chassis movements are relatively slow. The motion and velocity that is reached just from the chassis moving around never gets that fast. All your low speed damping controls this and helps keep the ride from being jiggly, bouncing, boundy, or otherwise move excessively. You don't really get into the high speed stuff till you start running over bumps at speed. High speed is driving over pot holes, washboard, and expansion joints. These are surfaces that have a very rapid change in elevation that asks your car's tires, wheels, suspension, bushings, and chassis to literally move out of the way in milliseconds. Dampers offer huge resistance towards this motion. While a 250 lb/in spring can run over a 1" bump and impart 250 lbs of force upon the chassis after compression (slowly pushing the chassis up), a damper can impart high resistance to that fast motion upward and impart north of 2000 lbs of force onto the chassis. You get a lot more chassis motion due to that resistance and higher transmitted force. If it is sufficient, it can upset traction by literally shoving the car up into the air some. A kinked compression profile will offer high low speed damping for control but cut down high speed resistance. Over the same bump at the same speed, only 1000 lbs might be transmitted.

Now 2000 lbs of force may seem bad, but there is still worse. If you bottom out the car, there is zero compliance outside of metal flexing. Low cars still are kings of impact force. Dampers at least allow movement, but once you're bottomed out, there is nowhere to go but shove the chassis up. You can end up exerting significantly higher forces upward onto the car simply through a lack of suspension travel. When you hit a bump on a lowered car, it has to go up. Tires will compression, bushings will compress, and what little suspension that exists will get compressed. Then the chassis will flex some. After that, it's very high force shoving the car up. If significant enough, you can wreck stuff. You can pop tires, bend suspension pieces, bend the strut, bend the chassis mounting point, all if the chassis can't move out of the way fast enough. At least with a stiff damper, the worst you might do is damage the valving or pop a seal. If you have the range of travel, you will have the compliance. For example, I've driven over a lot of stuff with my Forester up at 16" fender to wheel center. I've done rally-x and hit some hard ruts. I've run over a 4" curb at 20mph. I've hit 2" cuts in concrete (redoing the road surface) at 65mph on my summers. Nothing happened to the car, and I'm running 350 lb/in springs up front with the D-Spec damper set max. Why? Because I actually built in the range of motion necessary to do so.

 

KOLB! Hit me up is you need a hand buddy. I'd be more than happy to help a fellow suby enthusiast...what kind of plans are you thinking for your build. I know someone who has a 205 shortblock that needs a rebuild if you're feeling REALLY ambitious

 

Joebush, I'll be needing all the help I can get! I have a thread in the Mod/maitanence section at 2002 WRX build assistance with a rough outline of the things I'm planning on putting on. I've already got the 205 in the car that I'll be putting new parts on, if this one fails, then I might just upgrade to a 255 next time and do this right! lol

 

It will be interesting to see what cars make it out to proving grounds this year. Only about 6 months away!!!! What do you have planned for modications on your car??

 

Unknown for modifications but I'll be there again for my third year! Always a blast. Loved the cruise from MAP last year too!