d-sport

I know this is rarely done, but I'm considering swapping my front sway back to stock. I installed the Whiteline bars, front and rear, about 6 months ago. Those combined with coils have produced definite Understeer problems for me. I am unable to trail brake the car, and battle with mid corner and exit push.

Here is what I have on the car:
Feal441 maxtravel coils (8k front 10k rear) (changed from 7k f, 8k r) and revalved
Stock ride height
Whiteline sway bars (rear set to full stiff)
Gramlight 57c6 18x9.5 +38 275/35/18 140 tread wear nt05's

I really feel like I'm out of options here, not sure if I would benefit from any kind of roll center correction or rear bump steer correction? Im new to Evo's, but have hundreds of hours of seat time, professional racing licensed, and previously a track driving instructor.

Any help appreciated

MinusPrevious

iTrader: (3)

I think youre making the right move.

Although i have not used a higher rate FSB, I have investigated the issue w/some of the best susp tuners in the biz (Mueller / Robi & numerous high level EVO racers) (The consensus is to stay w/the stock rate FSB)

We all know the EVO is understeer prone & adding higher rate springs coupled w/a higher rate FSB is increasing the understeer tendency. Its one or the other. You cant increase both component rates & expect a performance gain in the way of rotation

I run FA510's 10k/12k, 24mm RSB set on Med & a stock FSB using adj WL endlinks

Anyway, its a heated topic & Im mostly outnumbered in this opinion as I think most guys are not truly tracking their EVO's but running these high rate FSB's & high rate coils on the street

Keep us posted

BTW, i remember reading your Feb 2016 post

alleggerita

Unless you already have a remapped ACD ECU and a restacked or modified rear diff I would keep the bar ....

Bumpsteer bushings in the rear are also worthwhile, as well as trailing arm bushings.

RCK probably not so much given stock ride height.

Once you have done these you will know whether you will still want to pull the bar.

Biggest bang for the buck is ACD remap ....

Jonno99

My car came with front and rear whitelines on standard springs and shocks on standard rims. Back bar is set to middle hole, handling is neutral. If I over cook the entry speed and throw it onto a 90 degree turn it actually slides sideways, ive never lost the front even when I tried in the wet for fun the back cut lose and spun my around so quick I couldn't catch it. When exiting a fast sweeper on boost I always get an oversteer feeling which suits me, I'd love to get coil overs but why screw with a car that handles well as it is.

ReidFletcher

iTrader: (1)

Leave the front sway in place. A locking rear diff is the next step. Weir or TRE are the common solutions for resolving understeer. I have the same 26mm F/R white line sways. Car pushed pretty badly. Weir 12 plate kit with Redline 75w140 installed and now the car is understeer free on track. On street tires you can really toss the rear out where ever you want. Aha

MinusPrevious

iTrader: (3)

Guys

Cant argue the fact that the EVO, by design, is understeer prone. No way to drive around that design fact

The rear diff modification / upgrade only addresses a power application process 1/2 way out of the turn (past the apex)

The rear diff modification / upgrade does not address the deep dive, off throttle, into the corner

Adding the upgraded plates / re-stack does not change susp geometry!!!

BTW, wheres the OP?

d-sport

*****update*****

So I got a chance to test the new setup. Before re-installing the stock rollbar I drilled a new hole on each end to give some sort of adjustment. I'm pretty sure you can find it by searching "Evo 9 stock adjustable sway bar mod". I'm not exactly thrilled about this, but the idea was to give me some options since I'm really trying to dial the car in. I installed the stock bar and placed the end links in the new holes I drilled. No other changes were made. Rear is still a Whiteline on full stiff.

***into***
So 2 things I wanted to touch on first. The Rear differential (or restacking) and ACD tuning. Feel free to scroll down if your just interested in the sway bar change.

***The rear differential ***
Coming from a RWD background, you can bet that I've spent some time working on differential tuning. I've restacked my fair share of differentials, and am familiar with how break away torques, and different clutch types (1, 1.5, and 2way) react to driver inputs. Here's the general rule of thumb: Lesser is better. What I mean by this is that we work from LESS lock up, and work our way up.

Why? Because lock-up restricts the differential. Remember, the outside wheels follow a larger turning circle. And NEED to spin faster. If unwanted wheel spin is not prevalent, Increasing lockup results in less lateral G's. The oversteer is a result of loss of rear grip. Giving the Illusion of faster cornering speeds.

***ACD Tuning***
I don't claim to be an expert on this section but I can point out the obvious. The Evo US spec 9 uses a rear wheel "assist" style AWD system. That is, it will vary power input to the rear from 0 to 50%. The truth is, the stock ACD tune allows 50/50 power distribution a VERY VERY small percentage of the time, if at all. From there I'm lost however. I just don't have enough first hand experience with center differentials to comment on handling. But I'm strongly considering an ACD tune.

***Initial impressions*** Whiteline vs.stock

Right away I noticed the car seemed to be a lot less "darty". Steering (with the stock bar) feels slower in contrast to the Whiteline. Got rid of that "gocart" feel. But let's get to the less obvious.

Less body roll doesn't necessarily mean more grip. And this seems to be the exact case with the bar. When on throttle, the car plants itself much better. Feels much more neutral. There is no power oversteer but there is oversteer, fast oversteer. At one point I got about 30* of countersteer on a 90mph sweeper. Really the most I'd ever feel comfortable with on a FWD/AWD car on a paved track.

***final impressions***
The Whiteline front swaybar was simply too stiff. I'm guessing an ACD tune down the road will cause me to step down the setting on the rear swaybar. But I cannot see a case that would cause me to reinstall the aftermarket front bar any time soon.

d-sport

MinionsPrevious, I've been meaning to get back to your first response, but you really hit the nail on the head with this one. The key is to correct the chassis dynamics. Throttle should be used as a tool. Not a Fix

P.S. I can't believe you remember my first post haha.

MinusPrevious

iTrader: (3)

Just want to make sure we are on the same page. The EVO AWD system is a true 50/50 split, all the time. The split is all mechanical & there is never any front to rear bias

Read this most informative post taken from Mitsu factory fact:

https://www.evolutionm.net/forums/ev...everybody.html

alleggerita

Different strokes for different folks ....

IMO give me a working rear diff over a stiffer rear bar any day ...

YMMV

alleggerita

AYC equipped car is a very different kettle of fish than USDM car with regard to understeer.

V.8MR

iTrader: (6)

I wonder how grip affects this. If you have say a 275 R Comp tire, with more grip there should be more roll. I'd argue a stiffer bar is warranted as the grip increases.

kyoo

iTrader: (29)

I avoided the WL FSB because it did seem too stiff - I went with a Tanabe Sustec, Whiteline rear bar on soft, and otherwise similar suspension set up, and I did get yaw/very neutral on trail braking.

differences include front control arm bushing, rear trailing arm bushing, bumpsteer kit, roll center adjuster, superpro bushings, ciro caster plates, etc. + English Racing ACD tune and Cusco rear diff.

Your comments about the rear diff aren't completely true, at least from what we've seen anecdotally. yes, too much lock up will result in push, especially a 2 way (most aftermarket for our cars are 1.5way) it completely depends on the design of the differential, as I'm sure you are aware.
what you want low initial lock up/low torque, and ramp it up on power. open or somewhat open on decal, and more lockup on power. the part you don't mention is the torque that is sent to the other side on power - it's just not about the diff trying to bind the wheels together. I don't think anyone with a well-set up aftermarket rear differential has noted slower lap times - in fact, most immediately pick up gains.

my car, with the above mentioned setup, was very loose in general. a lot to do with driving as well, but on the track with the fsb the car was pretty much ideal for me, and in autox it swings through a wide range of behaviors depending on how poor my driver inputs are.

also, as minusprevious mentioned, no truth to your comments regarding the ACD. it is 50:50 power distribution all the time, period. what does change is the amount of lock up between the front and rear wheels, just like a limited slip differential (which it is). ACD tunes adjust how much lock up and when.

d-sport

Everyone's free to their own opinions. I just figured I'd try to help out a few guys with their setups.

Like I said, I don't claim to know much about ACD. It's one of the first things I mentioned. I was just going off what I've read, feel, and tire temperatures. Apologize for any misinformation, there is a lot of it out there. I think that's where the confusion lies. But the f/r power destribution under load is most certainly NOT 50/50 all the time. If it was, there would be no need for ACD, or any kind of differential for that matter. 50/50 under no load and cruising down the highway, that's entirely correct. There is no bias.

To each their own on thoughts about how the rear diff is keeping power on the ground. You can think of it as sending power to the slower wheel, as you said. This is true. But the more accurate truth is to think of a clutch-type differential as locking the rear wheels together (as this is what is mechanically happening) The negative side-effects aren't just push, they are literally a loss of rear grip.

d-sport

Awesome MinusPrevious! Thank you for that article. Very informative. I believe we are on the same page. It's amazing how many people are/were confused on this, especially myself. My previous searches almost brought up more questions than answers.