Dallas J

iTrader: (1)

Background,
Im a mechanical engineer (MSME), did FSAE suspension for a year, and spend most my free time reading about suspension design and setup and one day I hope to go somewhere as a suspension engineer. My normal autocross car is a 95 Eagle Talon that Ive been running for 6 years. Its nearly completely built, 2.4l, aftermarket diffs, 275 V710s...etc. Unfortunately I had motor apart waiting on parts so it wasn't ready for a points event so I decided to take the evo and see what she'd do.

The results,
Understeer, Understeer, Understeer! The Evo was 5-6 seconds off my pace in the Talon (it was a ~55sec course), and please dont tell me to fix the driver hoopla, I may not be a national driver but I am a front runner locally and know my way around an autocross course .

Whats on the Car? Just a downpipe, test pipe, flash, hotchkis spring/sway kit, and some BFG dry/wet tires. My best estimation is about -1* camber front and maybe -0.5* rear.

Ok, so whats wrong with the car. Basically, the hotchkis kit sucks. Lack of front spring rate meant the turn in was way to slow. You had to baby the wheel into turns to get the suspension to settle and grip, otherwise it would just understeer, not transfer any load, and the maximum grip would fall off immensely. Also I think the front was hitting the bump stops on some of the rougher section. Although it did a great job of putting power (well, lack there of ) down through soft turns.

I will wholeheartedly say the hotchkis kit is pretty terrible for anything other than looking low and having a soft rolley polley front end .

The fix,
Since this is the "Wet Event" car Im keeping it simple and relatively soft. I ordered up a set of GTworx springs (Similar rear rate, 50% higher front rate, less drop). While in there Ill re-drill the front bar for some extra roll resistance adjustment (also take some measurements so I can get a rough % change figure). Set max camber within the stock equipment in front and ~ 0.6% of the front camber in the rear.

Next year Ill be switching over to the Evo full time to start competing PAX in BSP to see how I fare against our slew of national champions. I know theirs lots of potential in the Evo, just gotta work on unlocking it. Next year will be time to spend some money on suspension, but for now we'll see what she can with minimal monetary investment

delongedoug

iTrader: (20)

Hang out with this guy: https://www.evolutionm.net/forums/ev...did-so-so.html

vicksen

iTrader: (22)

You might want to leave the front sway bar alone and focus on the rear. If you stiffen up the front you will cause more understeer.

Dallas J

iTrader: (1)

That generalization only really holds true for cars within a good setup range. Take for instance subaru's. The guys who run stock class upgrade the FSB. It reduces roll in front and maintains a better contact patch..Net grip increased. Out of the handfull of guys who have made 2g faster, we've all found increasing front stiffness increases grip. Its all about making the tires happy.

It also just gives another level of adjustment (6 sway bar stiffness combinations) for the cost of some good drill bits. If I feel its causing un-balance its easy enough to change back to OEM holes.

spdracerut

iTrader: (2)

I'd say the springs you have on there now are definitely an issue. How far are you allowed to modify the suspension for BSP? On road courses, rear trailing arm bushings and rear bump steer correction are known to help the rear rotate. I had these and front camber plates (-3.0f, -1.5 rear), otherwise stock suspension, and I could get the rear completely sideways with abrupt lift throttle at ~30mph corner entry.

Dallas J

iTrader: (1)

Suspension is fully open in BSP, pretty much same as SM. SM just adds engine and some aero mods.

I have a full set of energy suspension bushings my roommate has left over from his Evo (he never installed them). Ill probably put on the important ones this winter (LCA's and trailing arms, any other especially important for the evo?)

Next year will be either Ohlin DFV or AST 5100's...Havent decided between the two and that might end up being a choice between the 5200's and Flags. Just depends on how much I feel like spending at the time .

Right now, in the dry the car wont kick sideways like my Talon or roommates evo on Swifts under power.

The point of this thread is basically just to keep track of my feeling on the car throughout changes.

FJF

iTrader: (18)

Subscribed. Looking forward to your impressions of GTWorx springs.

scorke

iTrader: (18)

To even attempt to really push an evo without an alignment thats even aggressive for stock is like test driving a car in reverse.

It tells you something but I'm not sure what.

Scorke

Smike

iTrader: (8)

Alignment - more camber.

GTWorx springs are stiffer front are rear, keeping the correct motion ratio for the car.

And thats not what sway bars too RSB influences the front of the car, and FSB and changes the rear.

Dallas J

iTrader: (1)

Its more about seeing where the car started and to give an idea of what needs to change. If the front folded over that easy on a weak alignment, imagine how bad it would have been with more grip...Get what Im thinking?

Anyways, Springs should be here soon and Ill get the Evo back out to another event. Great thing about this location, I can race every weekend with different clubs .

SmikeEvo: Its not that simple. A RSB effects both the front and rear, same with a FSB. Upgrading the FSB will reduce front roll (reducing dynamic camber loss, IOW less positive camber motion) by transferring more load to its outside wheel but also has an effect of increasing load on the inside wheel at the opposite end of the car.

Edit: I think I miss-read Smike's post...He probably meant FSB changes the rear also.

rburris28

I run in BSP, but just because of an aftermarket clutch and flywheel.

So I got a tune, added camber plates on the front only set to -3 (rears are at -1.5) with zero toe front and rear, and I couldn't be happier with the rotation.

I have been campaigning this for three years now, so being used to it may have something to do with it, but I usually get beaten only by better drivers, not better setups.

I normally finish second or third out of 90 or so cars (to fully prepped STU cars, usually, with more experienced drivers running a few tenths faster. I can afford a full suspension, but I keep waiting until I am getting beaten worse for raw time before I consider the investment worth it.

TommiM

iTrader: (19)

It must be the hotchkis setup. I finished first in my class last year with just robispec springs, kuhmo xs, and a good alignment.

Smike

iTrader: (8)

Yes, effects both.

Dallas J

iTrader: (1)

Tommi, you're pretty much a step up on tires, springs, and alignment. I'll be there (minus the tires cause it's the wet car). I'll be documenting all my changes and the growth/developement. Expect some real math and suspension pickup point plots in the future .

MinusPrevious

iTrader: (3)

Yesterday, While at the FSAE event in So.Cal I inquired w/ the boys as to your dilemma.
(Aside from some basic set-up issues) You maybe just over driving the EVO. They told me to tell you to "Slow Down to go Fast"=)