Oversteer and understeer info

[eagle1]

This question is for any one that really know whats happing with a car in each situation. Just trying to understand once and for all what a car is doing under each one and benefits if any. I think oversteer is when the back of the car slide out in a turn but not sure. No idea on understeer! Also how tires size plays a roll in it. Thanks
Semper fi

[banter]

Understeer is when you are going into a turn, you turn the wheel and your car doesn't follow the tires and keeps going forward more rather than turning. Much like over steer, there are varying degrees/severity (worse case scenario your car keeps going completely straight) to it but that's the jist of it. Very prevalent in FWD and AWD cars due to the from wheels being fed the power while cornering, but it can happen in RWD cars too (generally from trying to carry too much speed into a corner). No benefits to it at all.

Oversteer is when the rear end slides out during a turn. Generally when you try to put too much power down through a turn and don't have enough grip or downforce so it breaks the tires loose. It can be fun or used to get yourself out of an understeer situation.

Generally both of these come from a lack of grip and/or downforce through a corner. Larger tire sizes increase the contact patch with the road therefore increasing grip.

[BlackinBlack]

Always can use the NASCAR terms.

Understeer = PUSH as in the car is not turning but pushing straight into the wall.

Oversteer = LOOSE as in the back end of the car is loose.

Most cars are built with understeer, as dealing with the car not turning is easier to recover than a car that is beginning to spin. People's first response to a car running over the performance limit is the lift off the power. On a car with understeer this will slow the car and it will recover. With oversteer you just made things worse and most likely induced a spin.

[Jeff_SS]

[Todd in Vancouver]

My understanding is this, when you are going into a corner and the car is not turning how you want so you put more and more steering into it = oversteer. When you are going into a corner and the car pushes to the outside of the road it's under steer. When I went to driver training they were teaching us how to modulate the gas pedal to control it.

[Shift_Rejected]

Under-steer cost me my first SS a few months back...

[PalmerGA]

Originally Posted by Shift_Rejected

Under-steer cost me my first SS a few months back...

Are you sure it wasn't too much speed that caused it?

[eagle1]

Originally Posted by banter

Understeer is when you are going into a turn, you turn the wheel and your car doesn't follow the tires and keeps going forward more rather than turning. Much like over steer, there are varying degrees/severity (worse case scenario your car keeps going completely straight) to it but that's the jist of it. Very prevalent in FWD and AWD cars due to the from wheels being fed the power while cornering, but it can happen in RWD cars too (generally from trying to carry too much speed into a corner). No benefits to it at all.

Oversteer is when the rear end slides out during a turn. Generally when you try to put too much power down through a turn and don't have enough grip or downforce so it breaks the tires loose. It can be fun or used to get yourself out of an understeer situation.

Generally both of these come from a lack of grip and/or downforce through a corner. Larger tire sizes increase the contact patch with the road therefore increasing grip.

So banter if its oversteering correct by applying more throttle to counter the understeer or slow down. Don't like having to slow down not in my blood. Oversteer is just to much throttle in the turn. Thanks

Originally Posted by BlackinBlack

Always can use the NASCAR terms.

Understeer = PUSH as in the car is not turning but pushing straight into the wall.

Oversteer = LOOSE as in the back end of the car is loose.

Most cars are built with understeer, as dealing with the car not turning is easier to recover than a car that is beginning to spin. People's first response to a car running over the performance limit is the lift off the power. On a car with understeer this will slow the car and it will recover. With oversteer you just made things worse and most likely induced a spin.

blackinblack make sense, i heard that so many time in nascar when the crew chief is talking to the driver and as soon as he pits, the one guy is cranking on the bolt in the rear glass. If they build the car with understeer what in the front end is making it understeer? Would just putting bigger tires fix it! Thanks for the info.

Originally Posted by Jeff_SS

Picture is worth a thousand words thanks i dont want to crash my camaro into a tree for sure. Thanks

Originally Posted by Todd in Vancouver

My understanding is this, when you are going into a corner and the car is not turning how you want so you put more and more steering into it = oversteer. When you are going into a corner and the car pushes to the outside of the road it's under steer. When I went to driver training they were teaching us how to modulate the gas pedal to control it.

Todd, so the school is saying to deal with it by applying throttle to bring it back. I used to run around in a chevelle in the snow back in the day to scare to jesus out of my girl by kicking the back out to both side of the road. I been thinking about getting some info on the the Atlanta track. Might be something to get after. Thanks for the info.

Originally Posted by Shift_Rejected

Under-steer cost me my first SS a few months back...

Man not good, thats what i dont want to do. Thanks

[Normagene]

Like with anything in life, the more times you do it the better you get at it. I was coming up to an intersection and the light turned yellow, temps were only in the hi 40s, so I had very very little grip needless to say. I was doing about 40/45 coming into the turn and sure enough I started sliding sideways, understeer, the front wheels just wouldn't track. And of course there just happened to be this huge concrete wall that just kept coming closer and closer! I let off which helped bring the weight to the front and I was just a foot or two at most from taking out the entire passenger side. That got the heart pumping. Problem was I had done that same turn many times in temps closer to 70 which made the tires stick like glue. A ZL1 in Cold temps guarantees under/oversteer!

[SSeniorMoment]

Originally Posted by 130R

You're describing the same thing here… Understeer.

When the car isn't turning and requires more and more steering input, the car isn't turning enough, or "understeering". This is the same as the car pushing forward, or to the outside of the road as you put it.

Oversteer is when the car turns more than the steering input, requiring less, or even counter-steer to get the car to follow the intended path.


You can look at it this way: if you have to add more steering, the car is understeering. If you have to reduce steering, the car is oversteering. This is just to clear up your definitions. Merely adding more steering may not reduce an understeer condition.

+1

Over the weekend I was working on 90° turns and gears. Depending on length of turn and bank, paddle down to third, ~3,000-3,500 rpm 60-65mph with stock 3.27 rear gear. FE3 suspensions are notorious for under steer, anyway, I'm into a right turn that has a decreasing radius and I could literally feel all the push going to the left front tire as I turned the steering wheel sharper, understeer = push.

Pfadt FE4 conversion with ZL1 spec sways in the near future.

[eagle1]

Originally Posted by 130R

You're describing the same thing here… Understeer.

When the car isn't turning and requires more and more steering input, the car isn't turning enough, or "understeering". This is the same as the car pushing forward, or to the outside of the road as you put it.

Oversteer is when the car turns more than the steering input, requiring less, or even counter-steer to get the car to follow the intended path.


You can look at it this way: if you have to add more steering, the car is understeering. If you have to reduce steering, the car is oversteering. This is just to clear up your definitions. Merely adding more steering may not reduce an understeer condition.

Do you think that the 1le has understeer or oversteer. That is with a good driver that knows what he's doing?

[wadeh]

There are two causes for oversteer, and the correction for each of them is very different.

You can get oversteer by entering a corner slowly and then applying throttle on a rear wheel drive car. In this case, you can correct the oversteer by lifting throttle or with opposite lock (steering opposite the direction of the turn). This is the kind of oversteer that is considered fun - and is what drifting is all about.

The second kind of oversteer is responsible for getting cars wrapped around trees. This happens when you enter a corner too fast. What happens is that your 4 tires are gripping the road, but the driver panics and lifts off the gas. When the lift happens, weight transfers from the rear wheels to the front. The lighter load on the rear wheels causes them to lose grip, and the back end very quickly comes around and swaps places with the front of the car. The best thing to do here is to avoid the situation. And if you find yourself in a turn faster than you want to be, you need to drive through it and resist the urge to lift the throttle when you are at the limit.

[Egon]

You can also think of it like this. Understeer is a behavior when your front wheels are losing traction, and oversteer is when your rear wheels are losing traction. When your front wheels lose traction the car will tend to “push” forward in a straight line and to correct it you will have to increase your rate of turn just like when you see people driving on icy roads and they are turning the wheel to full lock but the car is moving in a straight line instead. When your rear wheels are losing traction the rear of the car will tend to swing around and your rate of turn will increase much faster than you intended just like if you were doing doughnuts in a parking lot. The oversteer condition can be initiated by adding power as when a drifter is going around a corner, they intentionally break the rear wheels loose. This is also why many people will refer to it as steering with the throttle. If you are not turning fast enough, add gas and the rear will swing out more causing you to turn sharper. (or cause you to spin out) The 1LE is intentionally set up to be as close to neutral as possible but I would assume as others have mentioned here there is probably some light understeer/push built into it at the limits since that condition is usually safer than an oversteer condition.

[Norm Peterson]

Originally Posted by eagle1

Oversteer is just to much throttle in the turn.

That's power-on or throttle oversteer, which is a specific means of getting oversteer through intentional driver input. Not what the chassis inherently wants to do otherwise.

black make sense, i heard that so many time in nascar when the crew chief is talking to the driver and as soon as he pits, the one guy is cranking on the bolt in the rear glass. If they build the car with understeer what in the front end is making it understeer? Would just putting bigger tires fix it! Thanks for the info.

The guy cranking on the track bar adjustment may be making it either tighter (more understeerish) or looser (less understeerish toward but probably not all the way into oversteerish), you just don't know unless you know which way cranking the adjuster does which.

In strict SAE terms, understeer is when the front tires are running at larger slip angles than the rear tires are, and the front of the car sort of slides toward the outside a little more than the rear does. It's not exactly sliding like you would on the snow (that much of the Eastern part of the country has been getting) with locked brakes, but it isn't 100.00% pure rolling either. Oversteer is obviously when the rear wants to slide a little wider than the front (and it doesn't take a whole lot of the rear running wider to get your attention).

Originally Posted by eagle1

Do you think that the 1le has understeer or oversteer. That is with a good driver that knows what he's doing?

The 1LE has what most authorities would call "light understeer" or perhaps mild or minimal understeer. Basically it's closer to neutral than the SS it comes from or the LS/LT/ZL1. "Neutral" is where the front and rear slip angles are equal and neither end of the car wants to run wider than the other.

Although neutral sounds like a good place to set up at, it's generally too touchy for most people to drive because it's too easy for them to unintentionally to dip too far into oversteer than they are comfortable with or can even cope with at all. Only a little throttle will instantly move a near-neutral steer car well into oversteer (power oversteer, actually). In the case of a ZL1 on cold G:2's make that a tiny amount of throttle. The mechanism here is that the rear tire slip resulting from acceleration effectively steals grip from cornering and causes the rear slip angles to increase. It's how you can snap a RWD car around in gentle donuts in the snow with just a light touch on the gas (did a few of those today myself in the deserted neighborhood pool parking lot practicing a little toss and catch).

Even gentle throttle inputs can change the amount of understeer. As noted earlier, just lifting off the throttle will transfer a little load forward. This reduces front slip angles - and increases the rear ones, both effects working to reduce the understeer.


It's a fascinating topic.


Norm