Low-Speed Corner Understeer

[MrMigs]

On high speed and medium-speed corners, my car will oversteer a little when I trail brake, but on low-speed corners, my car goes right into understeer. I try steering slowly, but it's a problem i can't seem to get rid of.

On other turns, it feels like I have more time to rotate the weight to the outside of the car, but on low-speed turns, it feels like the weight isnt able to move to the outside of the car. When I add braking, even a little, the front wheels either lock (and i have to let go of the brakes) or the front wheels just start losing grip and my turning radius increases.

Any tips that could help? BTW I have adjustable koni shocks. Any settings anyone could recommend for me?

[sykikchimp]

what do you have your shocks set for?

what springs are you using?

What are your alignment specs?

[MrMigs]

My shocks are at 1.5 (3/4 a full turn) all around from the softest settings. Springs are KGMM S21 SuperSports... so 4.8 kg/mm in the front at 4.0 kg/mm in the rear.

In my quest for craziness, i took off the front swaybar, which seemed to level-out the car a little bit. I have a front stb though, and the stock rear sway bar.

My alignment is like... damn i dont know the exact measurements, but I'll try to give an educated estimate:
front: a little toe-out .. maybe like i dunno... .075 degrees of toe out. Then I know I have approx 1.7 degrees of negative camber.
-----
The rear: I have a tiny bit of toe-in.. close to zero, and about 1.0 degrees of negative camber.

Tires are Bridgestone Potenzas re010 set to 30 psi (cold) all around.

*I'll check the car in a little while... I have to walk from the dorm all the way to the garage. I think I have my alignment papers in there somewhere. Also, the bushings on my tc rods are leakin'

[DuffMan]

You could try a stiffer front sway bar, and then compensate with stiffer rear springs or shock setting, or less air pressure in the back.

This will give the car a bit more oversteer going into the turn, and then once you are in the turn and body has rolled, lock in the rear by adding front stiffness.

[MrMigs]

i see... i see... I shall try what you say. So then... I should put the stock swaybar back on the front and then increase the rebound dampening on the rear shocks...and then I shall lower the rear tires by a a couple psi...

but what do you mean by "lock in the rear by adding front stiffness?" I am the little bit confuzzled

[DuffMan]

Well swaybars act differently than springs in that they get much stiffer the more you roll. When you are in a prolonged turn, and the body is rolling, they add a lot of front stiffness.

Front stiffness reduces oversteer/causes understeer.

This is good because it allows you put more power down without breaking the end completely loose. You could get the same effect without a sway bar, but it would lead to understeer where you don't want it (basicly what you have now).

RWD cars have a tendancy to understeer on entrance, but oversteer on exit. A bigger front sway bar can help ballance this out.

[MrMigs]

ah ha.... interesting. I understand what you mean now. I shall try this as soon as i can.

[AceInHole]

Originally posted by MrMigs
Tires are Bridgestone Potenzas re010 set to 30 psi (cold) all around.

Wow.... my tire pressure with 215/45/R17's is 40/38 at the autoX.... anything less would roll onto the sidewall.

[MovinUp-1]

Two things you have to do before you change any shock settings or anything else:
1) Most important change. Replace your T/C rod bushings that you said were leaking. Do this right away and do not race this car before you fix this problem.

2) Put your front sway bar back on. Removing the front bar is a drastic change that should not be done. I think your biggest problem is the suspension changing when you turn because of the broken bushings. When you fix those and put the sway bar back, then you can look at the little adjustments like shock settings and alignment.

[sykikchimp]

I was having basically the same problem with my coilovers when I got them.. I had them set to the lowest setting all around.. Car would plow, then snap to oversteer..

I raised the front setting way up to help turn in, and kept the rear fairly low to help with tail getting happy.

My settings are now 11F 2R dry.. usually about 13F 2or1R wet..

I usually play more with tire pressures to fine tune the car..

I also agree with Movinup.. Fix those Bushings NOW.

[ni*2*ss*4*an*0*]

just to add something real quick..i think your tire pressures are way to low.. i think 38-40 would be a lot better for you. i would chalk your tires once to see what kind of roll on those tires you are getting

[Bbandit]

on low speed corners.. keep the car balanced...
what i did.. brake first.. then release so i can get the nose up.. and then turn..
if your weight transfers to the front while you're turning.. it'll be more likely to understeer
so try to keep the nose up while turning on low speed corners

edit: but then again.. i drive a 100% stock koop

[240 2NR]

Originally posted by ni*2*ss*4*an*0*
just to add something real quick..i think your tire pressures are way to low.. i think 38-40 would be a lot better for you. i would chalk your tires once to see what kind of roll on those tires you are getting

I agree. I run 35psi on the street and I can FEEL when they get low. By 31 psi handling generally feels unresponsive and slow to settle. When autocrossing they're between 38-40psi.

[sykikchimp]

tire pressures really depend a lot on the tires themselves too.

I've found I get better grip with my Kumho's at around 40psi front, and 39 rear Hot.

[MrMigs]

but my max tire pressure says 35 on the sidewall.... wont anything higher be.... bad?

And also, in response to MovinUp-1, I had a feeling that blown tc bushings would mess up the suspension geometry when turning, so i was thinking about getting new tc rods... I just wasnt sure if they would help keep the suspension correct or not.

Also for sykikchimp, are those your rebound settings or your compression settings?

[sykikchimp]

Rebound.. I don't have 2-way adjustable shocks.. 2-ways are mucho $$$$$...