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AJ
12-11-2001, 12:11 PM
I have heard so much talk about oversteer and understeer, could someone explain exactly how this occurs, and at what times, and what are car has a tendancy to do in comparison to other cars.  Also, how will strut tower bars, front and rear, just front, just rear effect steering. thanks!

MingMing
12-11-2001, 12:37 PM
dunno bout hte strut stuff cuz i'm a total idiot, but anyway


fwd cars tend to understeer, rwd oversteer
(this is both during turning)

understeer is when u lose grip in ur front tires, and no matter how much u turn ur steering wheel ur car keeps going straight
thats cuz in fwd cars, when u accelearte in a turn ur weight shifts back, and ur front pretty much is lighter than ur back, so ur front wheels will have less traction than rears, and start slidin around

in rwd, when u brake into a turn, ur rear will be lighter than ur front cuz of weight shifting, and have less traction and slip around

HippoSleek
12-11-2001, 04:25 PM
Well, uhh, sorta what was said... best advice - track down DSC's signature and follow the link.

Understeer is when the front of the car refuses to change directions ("push" "plow").  It can happend in FWD, RWD, or AWD.  It is created by suspension geometry, weight, and power.  There is only one type.

Oversteer comes about in a few different ways - but mostly is either "trailing throttle" or "power on."  Oversteer is when the rear of the car does not follow the line of the front ("tailslide" "ass out" "drift").  Power on oversteer cannot happen in a FWD car - as the power is not in the back.  In RWD or AWD, a sudden surge of power can cause the wheels to brake lose and cause the tail of the car to take on a different track than the front.  Example: when you gun it in the rain and it slides around.  Trailing throttle oversteer can happen in any car.  Same situation, but it is created by getting off the gas around a turn, which causes inertia to move the weight of the car forward and off the back tires.  With weight off the tires and pressure on them to turn, they are unable to hold the same line as the fronts - a slide occurs.  Example - going around a turn and having to slow down b/c of a car in front of you.

Those are the basics - go to turnfast if you want more.

DSC
12-11-2001, 04:46 PM
Taken from turnfast.com

Loose handling-- (a.k.a. oversteer) occurs during cornering when the car's rear tires lose traction before the front tires. When this happens, the car begins to rotate about its center of gravity, and the back of the car swings out from the intended driving line.

Understeer-- (a.k.a. push, tight handling) occurs during cornering when the car's front tires lose traction before the rear tires. When this happens, the car will not turn as much as intended by the driver's steering input, and will start to drift to the outside of edge the turn.

Check out "weight transfer" and "anti-roll bars" in the "handling" section of Turnfast.com (http://www.turnfast.com)
Actually read everything you can find on that site, it rocks...has helped me a ton. But just read those two to answer your question.

AJ
12-12-2001, 04:05 PM
thanks a lot boys, that cleared up a lotta shit for me!

Chokudori
12-12-2001, 07:06 PM
In stock form, our cars will have some slight understeer. (It's safer this way)
There are couple easy ways to cure this. You could have slightly less air in your front tires, so they will grip better.
You could get a spring or an adjustable suspension kit that will lower the front by about half an inch compared to the back.  (You will have to test and tune this yourself to your liking)
You could also lighten your front part of your car(front of dashboard). Such as carbon fiber hood, aftermarket header, taking stuff off.
You could put some negative camber in your front tires. Ideal on race track is suppose to be about -2.5 degrees. But if you want even wear on your tires, you might just want to do about -1 degrees.

Strut bars don't really cure understeering.

Sway bars keep you from rolling. If you put stiff sway bars in front, soft on back.  you will more likely get some understeering. Stiff back and loose front will get you some oversteering.

The kind of setup you want to avoid are the ones when you force an oversteer by lowering the rear traction. This will just make the car unpredictable, and not improve your time. What you want to do is make the rear grip really well, and then make the front grip even more.

12-13-2001, 12:54 AM
So why do you need to step on the gas more if you understeer? Someone in another tread tried explaining it but I didn't understand. I had thought that you'd want to transfer weight to the front so the steering tires get traction. :\

MingMing
12-13-2001, 01:10 AM
yea ur rite, step on gas to fix understeer
but that's only in rwd cars
step too much and u get oversteer thou...
heh its basically, when u gas, the tires that accelerate ur car will have a higher tendency to slip, and when that one slips, if its in front, its undertseer, if its in back, its oversteer

LanceS13
12-13-2001, 01:17 AM
The thing about driving a car is that you really can't tell someone how to drive a car to its full potential...it's something that comes with years of practice.  In some situations, understeer will be worsened by using the throttle b/c of the rearward weight transfer; other times, it might help rotate the car by causing some slippage in the rear.  It just take experience to know how the car is going to respond to different inputs in different situations.  If you're really driving hard and you know your car pretty well, you can left foot break/right foot throttle to constantly balance the car in a turn.

12-13-2001, 01:24 AM
its easier in an automatic...... but u have to use the tranny bye holding the car back in a gear and that takes alot of control wheel both pedals and the shifter after u know ur car u can have some fun <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wink.gif" border="0" valign="absmiddle" alt=';)'>

LanceS13
12-13-2001, 01:37 AM
It's just the same in a manual...put it in the gear you want it in and you don't have to worry about the ECU/auto making decisions for you (when you don't want it to). &nbsp;
If you have to downshift to make the turn and you start to understeer, heel-toe the downshift but slightly under-match the rev to rotate the car. &nbsp;This takes alot of practice and is something I've yet to perfect.

HippoSleek
12-13-2001, 08:22 AM
A few things:
1) strut tower bars in front may actually INCREASE understeer as the stiffen the chassis and remove force from the chassis to the tires. &nbsp;WHile it makes a quicker and more positive turn in, it may also overload your tires' ability to maintain grip.

2) &nbsp;Understeer is preferable to oversteer, when setting up a car. &nbsp;It is safer.

3) &nbsp;When I get understeer in my car, I generally do NOT hit the gas. &nbsp;Unless your RWD car has a lot of power, Lance's explanation is right and you will more likely lose grip. &nbsp;Getting OFF the gas will cause the weight to shift over the front tires and off the rears which will more likely allow the front to re-grip and the back to reach slip angles.

4) &nbsp;Where you been Lance - finals?

LanceS13
12-13-2001, 11:58 AM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from HippoSleek on 8:22 am on Dec. 13, 2001
4) Where you been Lance - finals?</td></tr></table><span id='postcolor'>

Yep...I'm exhausted and really looking forward to Christmas break.

kitoro
12-13-2001, 02:07 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from LanceS13 on 12:17 am on Dec. 13, 2001
If you're really driving hard and you know your car pretty well, you can left foot break/right foot throttle to constantly balance the car in a turn.
</td></tr></table><span id='postcolor'>

does this work in RWD?<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>
i figured FWD... but RWD?

Chokudori
12-13-2001, 02:09 PM
Yup, I stomped on the gas while understeering on 2nd gear. (around 4000rpm I believe...) The car continued to understeer. It's pretty hard for our underpowered cars to start powersliding once in a medium speed turn. My next thought was using the side brake, but that wouldn't be very good for my tires, so I didn't do it. I pretty much have to let go of my gas.

But on low speed turns, I noticed that my S14 seems to turn pretty well, with slight oversteer.

LanceS13
12-13-2001, 02:14 PM
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from kitoro on 2<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/wow.gif" border="0" valign="absmiddle" alt=':0'>7 pm on Dec. 13, 2001
</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from LanceS13 on 12:17 am on Dec. 13, 2001
If you're really driving hard and you know your car pretty well, you can left foot break/right foot throttle to constantly balance the car in a turn.
</td></tr></table><span id='postcolor'>

does this work in RWD?<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/confused.gif" border="0" valign="absmiddle" alt='???'>
i figured FWD... but RWD?
</td></tr></table><span id='postcolor'>

did it all day a few weekends ago at an open track day <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>