Hey I Have a evo 9 with a few mods

not to long ago i got coilovers and ever since ive bin workin on setting them up

came a long way from getting them out the box but i still have a lil bit of understeer

List.....
megan spec rs coilovers 10k front and 8 rear rebound and compression adjustable
I swapped the spring from font to back so now it 8k front and 10 in the rear
whiteline rear swaybar stiffist setting
17x9 wheels
bfg ss tires
-2.5 front camber and -1 in the rear


when i am at low speeds 1st 2nd gear doing autox its pretty good not really any understeer i pick up a back wheel

but my problem is when i am goin faster like around 60 70 and going into a turn i get understeer all the way threw


can any one help or give me any advice

 

New to the Evo world?

You have a 9, so here are a few pointers. Most of the understeer issue is related to mitsu castrating the LSD rear diff (On US Spec cars) and putting some very lame programming into the ACD computer.

- Do the rear diff upgrade, single biggest understeer remedy for these cars. Shep, TRE or buy the 12-plate pack from Weir and do it yourself.

- The rear diff upgrade will really improve anything from apex through exit (rolling into more throttle). On longer sweepers at light-moderate throttle, the stock ACD unit still acts like a FWD car. And that causes understeer. You can fix that with a reflash of the ACD computer (Gruppe S or ACD Tuning). This will cause the ACD to send power to the rear wheels at lower throttle settings and situations. To get good results from this mod, you need the upgraded rear diff.

Then you get into understeer on turn in and general front end response. And making these better depends on what you are doing with the car and how far you want to take it.

 

There are several phases of a turn and where you have understeer will determine where you need a fix. The diff will fix/improve any area where you are using throttle but will have little effect on steady state.

I have tried so many combinations and I can tell you that you need more front roll resistance. Wont spill all the beans, but you need to both reduce front roll and front weight transfer. Also, picking up an inside rear isn't necessarily a bad thing when you're main goal is reducing front weight transfer.

 

Thanx for the tip guys I will deff look into the rear diff since I'm having the issues when I'm on the throttel under braking the cars great so hopefully that will solve that

 

Let's say one wasn't lowering the car (VIII), wouldn't increasing the roll-center height achieve this desired reduction in front roll and weight transfer? Wouldn't it help reduce understeer? Or do bad things start to happen?

 

This. Or even just restacking the factory rear LSD correctly.

Have played around with shock settings in the higher speed corners? You might have the front end too stiff. Autox and road course setups are 2 different animals. I'm in the process of making the transition from autox car to dedicated track car.

 

Too much rear sway bar will negatively affect you - aka lifting the rear wheels. It's also going to push though fast sweepers.

Rear diff is a good place to start to get the rear to step out more. Front sway bar is another.

First thing I would do is lower the RSB.

 

It might sound weird, but setting up a car on soft springs and stiff springs require two different approaches.

With soft springs you need enough bar to reduce roll and make the front tires happy, with stiff springs you need to reduce bar to reduce weight transfer in front.

You need just enough rear bar to hang the tire at max cornering load in steady state. Any more than that is a waste. A little lift is good, a lot of lift is not.

 

Cheapest thing to start with would be re-arranging the plates in the rear diff the way they should be. Will only cost you ~a day of working on the car and a rear diff oil change.

 

I agree, but the Weir plate pack kit is only $180 and while you have it out and apart.....

 

How much more positive is the Weir kit beyond simply re-stacking? Annoying on a DD?
Also, "while in there" should the diff mount bushings be changed? All four?

Thanks!

 

Can't answer the difference between OEM done right vs Weir. I went from OEM assembled wrong to Weir and that was a big difference.

As far as noise with the Weir, I would presume you could just add LSD friction modifier to the rear diff lube until you get it quiet enough to suit you. My car is track-only and I run Redline 75-90 NS (No Slip), and it makes ALL KINDS of noise. But it works great.

 

Using the NS fluid on my TRE diff was god awful. It made a ton of noises with the clutches slipping then grabbing. Switching to the mitsu fluid made a massive difference and on when its cold if I just pull out of a parking spot will it make any appreciable noise.

The bushings will also add a bit of diff whine to the cabin when on the freeway but that hasn't bothered me too much.

 

spring rates are incorrect fyi... plenty of suspension threads on this forum to look at, something called how to choose coilover rates is one of them

also, what's your a-x experience? maybe when youre going faster, you're going too fast lol that's my problem

 

He stated that he flipped the springs. I would take the other guys recommendations as a lot of them have been around for a while and have done a lot of trial and error.