ok, i understand that oversteer is when the rear of your car kicks out, and that understeer is when the front kicks out, but how does a car understeer. how does the front kick out? thanks

 

understeer is when you are moving forward at a given speed (30mph) and you try to make a 70-85 degree turn and your car doesnt want to go where you want it to go. meaning it still goes forward. very bad in my opinion

 

Turn the steering wheel, yet you go straight.

 

Understeer is the condition observed when the slip angle of the front tyres is greater than the rear tyres. Also known as "push" or the car is "tight".

 

exactly.
it can be corrected by transfering weight forward.

 

is having more oversteer better than having more ndersteer. like if i were to eliminate one of the two, which one would i choose? which one is eisier to correct?

 

not exactly. It can be corrected by returning to within the limits of that tires grip - usually by slowing down (left foot brake) and unwinding the steering wheel to plant the contact patch.

 

correcting understeer almost always requires you to slow down. Correcting oversteer can be done with steering wheel and throttle inputs.

 

or a quick lift on the throttle
I normally just open the wheel a little bit.

 

so understeer happens when you are turning and you input throuttle and the wheels spin therefore the tires slip and dont go where you want it to go.

 

Not exactly. Understeer is when the front wheels don't have enough grip to turn the car as much as the steering input would dictate. Put another way, the car is not turning as much as the streeting wheel is asking it to. The reason, the front wheels don't have enough grip to turn that much.

Easy way to feel understeer is to find a skidpad or a wet parking lot with nothing around to hit. Drive around in circles building up speed, eventually the car will not be able to hold the turn at that speed. With nice wet lot, it won't be much over 20-30 MPH. Even as you turn the wheel more, the car will not turn. Eventually you find the wheel turned full lock and the car going stright.

That is understeer.

 

I liked r2x's quote: "The cure for understeer is NOT more steer"

Like RJ said, the solutions to correct understeer while its occuring almost always require you to slow down. In a race situation, slow is really not what you want to do, so a car set up to understeer will likely not be found on the winners podium.

In a front wheel drive car, should you find the ***-end beginning to come around, the best solutions usually include standing on the accellerator. Slowing down generally aggrevates the situation. This is why you'll find just silly high spring rates and rear sway bars that resemble tree trunks on front running fwd race cars (say, a Realtime Type R for example)

Loose=fast, but you better have the nut behind the steering wheel torqued properly...


[Modified by MaddMatt, 6:38 PM 12/25/2002]

 

Remember understeer or oversteer are not static conditions. All cars can be made to understeer or oversteer by driver input alone. When people say a car understeers what they really mean is that in a steady state corner or on a skidpad, as the limit of adhesion is gently reached the front end begins to slide before the rear end.

Now for some important points -

1) ALL street cars understeer from the factory
2) Not all race cars understeer (as MaddMatt said "Loose=Fast" )
3) A car that understeers a lot is not the fastest race car
4) A car that understeers a lot is probably a very safe street car
5) All drivers are safer on the street with a car that understeers

So - if you have a street car DO NOT set it up like you would if it were a race car. (As MaddMatt said "but you better have the nut behind the wheel torqued properly" )

Ask anyone here who has a Honda Challenge car what a terrible street car it is. I always hate to see people say they want "race car handling" or a "race car suspension" for their street car. If they knew the facts they would not want it.



[Modified by 00R101, 6:24 AM 12/26/2002]

 

This is a tough question, SSLUDE. It pretty much hinges on the driver's preference and their abilities. I've seen guys go fast with oversteer AND understeer. It also depends on the track: on the ones with wicked tight turns, I'vw had some friends do well with massive oversteer (since they don't like to shuffle-steer). Personally, I do much better with understeer because I think it's much more predictable (i.e. the better setup for beginners) cause you're guaranteed to always go in the same direction...straight.

As RJ said, to keep the lid on understeer, you relax the steering input (just a tad) for just a split second then go back to normal input. During understeer, you've exceeded the grip that the front tires can provide with an excessive slip-angle. The slip angle curve is a really goofy looking thing because it's not linear (at extreme angles of slip, the tire loses traction VERY, VERY quickly and can result in a crash really quick as well). By continually relaxing the steering input a few degrees, you return the tire back to the slip angle that offers more grip, which can then rotate the car in the desired direction in slight increments. This, my friend, is called the ragged edge of physics...if you can do this perfectly, you're driving the wheels off of the car.

For more info about slip angles, check out a book by Carroll Smith called "Driving to Win". He's got a sample slip angle curve in there for you to see. I got my books from SAE, but someone told me his books are on Amazon.com too.


[Modified by archmanrsx3, 11:22 AM 12/27/2002]


[Modified by archmanrsx3, 11:23 AM 12/27/2002]