heel2toe

iTrader: (41)

Hello to all,

So I have been doing a bunch of research going through various threads and what not however I now feel the need to start my own. So here is the deal.

Lately I have been getting more involved in autocross. My car spends most of the time stored in the garage while I am at school however I do drive it when I am home for about 3 or 4 months of the year. Anyway I attended my first autocross last year. At the time my car was completely stock suspension wise and I was running the factory advans.

Since then I have installed Bilsteins with Espiler GT springs, a Perrin RSB and 245/40/17 star specs. As far as power is concerned she is pretty quick. Stock turbo however pretty much every bolt-on cams etc. Making about 350whp.

Well this summer I have attended 2 autocrosses. The car has done very well. Very neutral however at the limit she does love to understeer. The thing that gets me is that I used to never have issues with understeer and was able to get back on the gas corner exit and force the car to oversteer.

I understand that if I go into the corner too hot or try and brake while turning I am going to run into issues and that is completely understandable. What bugs me though is that I am no longer able to force the car to oversteer on corner exit. When I get on the gas it just spins the tires and it plows wide.

Currently I have the RSB set to full stiffness in hopes that this would induce oversteer. My theory is that its actually causing my inside tire to lift thus I am not able to get the power down and its more or less acting like a front wheel drive car. Does this sound reasonable?

So with that being said where can I go from here? I am running in SM and I understand that I really will need r-comps to be competitive however I do not want to spend money on another set of wheels and tires. I have been looking into the TRE rear diff and the Groupe-s ACD reflash trying to decide which one would be more beneficial to me. The other thing I am considering is adding a FSB thinking this will help however I really dont feel like installing one until I have to replace my clutch. The other thing I have considered is removing the RSB or loosening it up a bit. The thing that irks me is that I bought the RSB thinking it would help the car oversteer but I feel like its doing the exact opposite.

So based on my setup any insight that you guys/gals could provide would be greatly appreciated. Thanks in advance

shh!! sleeping

iTrader: (7)

Why are you racing in SM? you dont have cams in the car... you should be racing in either BSP or STU

With the rear sway bar being on the tightest setting... most 3 wheel action would be into the turn and up to apex... at apex the rear should be down and able to throttle on.

Your saying though you are understeering on exit of the turn? sounds like a line issue... or your punching it prior to or on the apex... at the apex you should gradually be getting on the throttle and at 100% at the exit.

What camber are you running on the front and rear?

Pure EvoIX

iTrader: (7)

Imho, to get the car to rotate better upgrade to coilovers and have the rear spring rates 2 or 3k stiffer. I think 8-10k front and 10-12k rear would be good for street tires on auto-x circuit. Still bearable on the street for DD. TRE rear diff will certainly help. Another thing you can benefit from is an aggressive alignment. What is your alignment set at currently? Of course, the upgrades are pending if they are legal in your class.

On a driving standpoint, be patient on the throttle, so you wont plow out of turns. Do more autocrosses and it will in turn pay dividends in terms of lowering lap times when you upgrade parts. Work on your technique for autox and see if you can tweak your driving style so the car can rotate better.

eve-slow

iTrader: (68)

The added width and possibly grip of the tires will hold back on your over steer. Try setting your rear bar on a lighter spec and I'd wait on the front sway bar all together, it may make it worse.

shh!! sleeping

iTrader: (7)

For street tires and no aluminum wing... i would reccomend a 9k front 13k rear. The stagger will def help you rotate.

Here is a list of suspension mods that i have and i rotate like crazy... the car feels like its rwd.

Stock MR suspension. Whiteline rear swaybar. BFG TA KDW's 255/35 GT Spec rear trunk cage, GT Spec front upper strut bar, GT Spec front 4pt lower brace.

stock turbo, stock block, stock mr 6 speed. and my swaybar is set to the middle setting.

I am also running -2.3 on the front and -1.7 camber in rear.

heel2toe

iTrader: (41)

Thanks for the quick responses. The reason I am in SM is because my car has cams and an external dump. The current alignment on the car is about 2 front and 1.5 rear 0 toe. I would like to get some camber plates and add some more camber.

I know coilovers will help however I dont have money to spend on those for the time being so that isnt an option.

I know seat time is really the most important thing here so my driving will improve. For a rookie I didnt do too shabby. Took 1st place last weekend granted it was novice class however I was only 1 second off FTD on a 40 second course.

I just feel like before I was easily able to force my car to oversteer but now its not responding the same way...

shh!! sleeping

iTrader: (7)

With a stock suspension the car is able to move and roll more because the springs are not stiff. The momentum of the cars weight as it rolls allows the car to swing more easily. By stiffening your springs and stiffening the rear sway you reduce the amount of roll. Your now increasing corner rigidity. The tires also are more grippy then stock tires so when you transfer the weight to the rear by hitting the gas the tires are harder to break loose now. Try and focus on your lines and smooth transition from brake to gas... Autox does not = 100% gas or nothing

boomn29

iTrader: (47)

I don't AX; I track but understeer is an issue with out cars to be sure. Most don't experience it because they aren't pushing it hard enough. With light suspension upgrades you can dial out most of it but you'll find it again towards the limits.
I recently put my 24mm Hotchkis RSB back on the car to try and help rotation - it didn't. So I moved it to the stiffer setting; then tightened my rear rebound and stiffened my front - still plowed under acceleration. In retrospect I should have tried softening the swaybar but live and learn!

Both the upgraded TRE rear diff and/or the Gruppe-S reflash will help you out with rotation and having the car behave more like a RWD car under power. I'd look into both. But if you can't afford tires; not sure where you're budget it.

heel2toe

iTrader: (41)

I know exactly what you mean and I understand that more seat time is crucial. I really dont want this thread to turn into a "you need to improve your driving technique". I already understand that and am fully aware of it. That will come with time.

In the mean time I really want to figure out what to change with the car's current setup as I feel something just isnt quite right. The car does handle really well however I just wish that at the limit it would oversteer rather than understeer.

heel2toe

iTrader: (41)

Boom-I appreciate the response. Its not that I cant necessarily afford tires or sweet coilovers. Its more that I am really trying to stop spending money on my car. Not to mention that if i am going to drop 1500 on something for my car I would like it to be something I could enjoy every time I drive the car. So thats why something like the TRE rear diff sounded more appetizing.

As for the RSB I was under the impression that the stiffer I set it at the more oversteer I would get. This doesnt seem to be the case. Is there a point where too stiff will actually induce more understeer? Do you think loosening it up a little bit or even putting back on the stock bar would be the better plan of action?

shh!! sleeping

iTrader: (7)

put it to the middle setting and test the car out... then put it to the lowest setting and test the car out... Trial by error is where you are going to tune in your set up

xmaciek82x

iTrader: (14)

Have you experimented around with the tire pressure. Bump up the rear tires to about 4 psi more then the front and she how you like it. Thats the advice I got when I was experiencing understeer, and seems to work really well.

heel2toe

iTrader: (41)

That sounds like the best plan of attack. Is it possible that if it were set too stiff the car would respond negatively and actually understeer instead of oversteer?

heel2toe

iTrader: (41)

As for tire pressures I have made significant adjustments throughout the event. I was running 37/39 f/r respectively. And those are the hot pressures BTW

shh!! sleeping

iTrader: (7)

Are you tripoding at all at the heaviest stiffness? I think ur Tire pressure might be a place to adjust also. Use chalk on the sidewall and see how far you are going down on the sidewall. If you increase the front pressure to 38 cold and rear to 40 cold and after every lap monitor your pressure not to exceed 42 hot in the front and 43 hot in the rear...

Play around with your pressures... this is what i found was best for my car to get it to act the way i want it to.