Heres an interesting SCCA thread posted by an EVO owner trying to reduce understeer

Your posted question, I believe, is correct. Decreasing understeer by softening the front spring or roll bar rate you affect the rear by increasing oversteer

Decreasing oversteer by softening the rear spring or bar rate you increase understeer

Thats my basic understanding

http://www.sccaforums.com/forums/aft/441543

 

it goes one way or the other, unless you can experiment enough to find the balance. even still, 'balance' is different for all of us.
personally, i like rotation during turn in so i can get on the gas early. i'm okay with the car feeling "loose" going in, as it straightens out once i roll on the throttle. i prefer that to a car that is tight and i have to induce oversteer to get the car around upon exit. for that reason, i'm trying one of Robi's RSBs. i'll play with that and see how i like it.

i'm no expert and my setup may be 'wrong', but it's how i like it and how i run the quickest times.

if this combination slows me down, i'll be looking into changing my driving style.

 

would the whiteline roll center adjustment kit help this at all as well?

 

I've had the car tracked and they said that there's a small bit of play on my lower control arms. I'm after ordering two along with a stiffer anti roll bar for the back. It's getting mapped Wednesday and I asked over the phone to do a diagnostics check on the ayc as we'll to thoroughly check out the suspension. I've 0 -camber at the moment .I'll be sure to check back when I get the results to see whats up.

Cheers for the answers

 

Not directly. It may indirectly since depending on how low the car is dropped helping to correct the geometry of the front suspension helps it work better but that's not its real purpose.

 

That is its real purpose. By raising the roll center, you reduce under steer, to a point. I say that because there is a point of diminishing return. We did this on my ranger when we built new front suspension. We set scrub radius at .5" off the SAI, 10* positive castor, -3* camber, and the roll center is much higher than OEM. With 14" of wheel travel, and 35" tall tires, it surprises everyone that rode in it with how much grip the front end has, and how well it handles despite 30* of body roll...ha . And that was with rear leaf springs. I can't wait for it to be done with the new 4-link out back, since it will give the rear suspension a real instant center and roll center. She's going to be an animal...

 

A more aggressive rear diff setup is best way to overcome the Evo inherent understeer.
You can start by restacking the stock diff to use all the plates. Or go more extreme like the TRE max lock http://www.teamrip.com/EVOLUTION%20R...20SERVICE.html

I have driven the TRE maxlock and can honestly say it can make an Evo oversteer on power.

 

It still pushes off throttle without proper trail braking.

 

Sounds like the car is setup stiffer on the front than rear?

 

stock sways, 9k front, 11k rear springs. Rear dampers are 2 clicks stiffer than the fronts. It rotates very well if I set the car properly, which is OK with me. Its very balanced, and doesn't snap oversteer when I left mid corner. I might get a slightly bigger rear bar, but I really don't want to gain that snap over steer coming off the throttle in a long corner.


The max-lock alleviated a good amount of the off throttle push, but its still there.

 

Bushings to avoid toe-changes and ACD flash may do the trick for you.

I had ACD flash, TRE diff, spherical front LCA. The offset Whiteline inner rear toe bushing in combination with spherical rear trailing arms eliminated mid corner push for me.

 

Those are my next steps. Have to save up dollars though. How is the NVH with spherical bearings on the rear trailing arm?

 

Strange. Close to my setup..But I never push on decel. Hm...

 

Could be tires too. I daily drive on bridgestone re760's. Haven't driven it on my track tires (Dunlop Z2's) with the new diff. So we shall see. With how much the diff helped, understeer may go away on stickier tires.

 

Not much increased NVH with sphericals except over road divider dots. I would consider a delrin or poly bushing fine for the trailing arm if you want to save some money.