||12-17-2006 06:04 AM
Good Evo susoension guide
I think we should first point out a number of the known weaknesses of the OEM suspension as delivered from Mitsubishi. As we al know, street suspensions are a huge bag of compromises. By weakneses, I am refering to those component areas that are routinely addressed by essentially all of the better suspension tuners. My somewhat uninformed and ovely brief list woulds have these items on it.
1) Rear trailing arm bushing is too compliant and should be replaced. There are at least 3 types of replacements:
a) AMS TPR plastic bushing
b) Whiteline polyurethane bushing
c) Nagisa pillow block style
2) Others might add the front control arm bushing. Most of these replacements that I have seen are the polyurethane type with a steel center bushing.
3) OEM springs are too soft even for the street and contribute to body roll and understeer.
4) Essentially no off the shelf spring sets or coilovers will perform anywhere near the level of the "tuned" suspension setups available from the half dozen os so quality Evo suspension vendors who provide very demanding component setup, corner weighting, ride height, and alignment specifications with thieir products. I think we should name these vendors and outline the proper way to successfully approach each one since they are all different companies. For example, some vendor(s) will come to your town and do installs and some won't.
5) OEM sway bars are matched to produce the corporately mandated "safe" understeer condition. A proper rear sway bar (adjustable) and a good street alignment will probably satisfy the needs of 75% of the street only driven Evo.
6) All susension tuning is a compromize amounting to a balancing act.
7) Don't go to a suspension designer and say I want it to be able to A,B,C,D,and E better than anything out there. That is the same as asking for a tire to be better than a Hoosier at the track while beating a Blizzack in the snow.
5) Adjustability can be a blessing and a curse. It is a blessing if you know what you are doing and a curse if you do not.
6) Sway bar adjustability can be a good thing. HKS seems to make both the most expensive and most adjustable front/ read sway bar package. See (Kami Speed)
7) Tires are a huge part of the suspension. Improper tire selection, inflation, tire management or alignment can and will damatically degrade the suspension's performance.
8) I personally believe there are negative camber limitations for predominatly street driven cars. However, I have seen and in my earlier years have driven autocross cars on the street with high negative cambers in a sufficiently aggressive manner that inside treadwear was not an issue. The solution here is the adjustable strut mount available fron a variety of vendors.