Oversteer is when the rear wheels are carving a larger arc than the front wheels or the intended line of the turn. Rear "slip angles" exceed those of the front tires. This is often described as a "loose" condition, as the car feels like it may swap ends, or be "twitchy." This condition can be caused by "power oversteer", where you need to reduce power in order to bring the back end back into line. <p>Understeer is when the front wheels are carving a larger arc than the rear wheels. This is often described as "push" or "pushing" - as the front end feels like it is plowing off of a corner. Further acceleration only compounds the push, as weight shifts back to the rear drive wheels off of the front turning wheels, leading to a further lessening of the car's ability to turn in. Understeer can be remedied by slight modulation in throttle to transfer weight forward to the front wheels, aiding their traction and ability to carve the turn. <br>
Stu Raike
12-16-1998, 02:02 PM
To the effect of...understeer is when you hit the wall with the front of the car and oversteer is when you hit the wall with the back end.<br>
klidge
12-16-1998, 04:24 PM
Bill Shaffer
12-16-1998, 06:08 PM
The Porsche 911 suffers from "lift throttle oversteer" This is the antithesis of what you describe. I don't have a better understanding of it than you, I just think we're all going around talking about stuff we rarely actually expierence.<p>Bill
Cathleen
12-17-1998, 05:23 AM
I HAVE driven RWD on a track but have never experienced a severe oversteer in one (yet), but I was told (by those who know) that if the back end gets loose on a RWD in cornering that you DO NOT LIFT or you are going for a spin. Instead you should press harder on the throtte to get it back in line.<br>I have had an oversteer that resulted in a 180 spin off the track in a Quattro which has, of course, some RWD characteristics. Unfortunately, this instance WAS caused by too much throttle input, too soon, on a greasy-wet apex. So more throttle was not the answer.<br>'Seat time' is what helps you to get the feel of the proper reaction based of conditions and situation. Then you can 'feel' and have the proper gut response. Remember, though, even first-rate race car drivers spin......no one is completely immune.<br>-C.<p>
John/TSR
12-17-1998, 06:58 AM
Oversteer is oversteer, whether it's from too much throttle or too little throttle. Ian's explanation was excellent.<p>TTO (trailing throttle oversteer or "lift throttle oversteer") is a characteristic of rear engine cars, and older 911's in particular must be driven gently when coming off the throttle when turning. <br>Any car will develop TTO if you snap out of the throttle abruptly in a corner, if you're really leaning on the suspension. <p>How to fix oversteer ? <br>FWD - Stand on the gas<br>RWD - (if caused by a throttle lift) gently squeeze power back in<br> (if caused by too much power) gently back power out<p>Recent 911 editions don't do it very dramatically, so much of what you hear is just 911 mythology. A well set up car can be steered with the throttle almost as much as with the steering wheel.<p>John<br>Trained Seals Racing
Ray Calvo
12-17-1998, 08:04 AM
Recovery from an oversteer condition requires a good feel for your car. In a rear-engine car like a 911, countersteering has to be quick (but not too much), you CAN'T lift off the throttle until the car is straight again, and you have to be quick with straightening the wheel again once the back end starts straightening out. Also have to be careful with amount of steering- too much can be worse than not enough. Have seen and experienced spins where the attempted recovery form the initial spin was overdone and the car went completely around.<p>if you want to experience understeer/oversteer, highly recommend autocrossing. You can get the car sideways and learn to recover. Race track driver's education give you excellent theoretical instruction, but no opportunity to learn skid recovery (if you DO get into an off-track experience, you've got a long discussion with an instructor; also high likelihood of doing car damage. Spin once too often and you're sent home for not keeping your car under control and driving within your abilities).<br>
John/TSR
12-17-1998, 09:35 AM
That's racing vernacular for what happens when you miss catching a slide, and spin it the other way due to overcorrection. It leaves a very distinctive "hook" tire pattern on pavement. <p>Most people are reasonably good at countersteering when the back end starts to slide. Where must people suck is in the "pause" and "recover" part, where you have to wait until the front end hooks up, then apply the CORRECT amount of recovery correction so that the car doesn't go the other way. This second slide is really very violent, as the rear springs are unloading from your first slide, just at the very time that your front wheels are probably pointed in the wrong direction just as they start to steer again. THAT'S the neck-snapping part of a missed slide recovery.<p>The most valuable time you could ever spend in a car is on a wet skid pad, or on ice. You'll learn more in 2 hours on a skid pad than you've learned in 20 or 30 years of driving. Skippy Barber's 1 day "Car Control Clinic" (if they still call it that) is well worth the time and money, if you don't want to drive like a wanker.<p>John/TSR
Dank
12-17-1998, 05:31 PM
!
Greg Slater
12-17-1998, 06:22 PM
The constant rain will give you PLENTY of opportunities to get used to the feel of your car sliding around. I saw a newbie guy two years ago in a brand new RX-7 lift suddenly at exactly the wrong time, and then (poorly) attempting to correct, leaving a nice "hook" pattern and a nice dent in his passenger-side door from when the car eventually stopped against a pole for a chain link fence.<p>Or, you can grow up in the sticks in Oregon like I did, and hope you have a bunch of neighbor kids with VERY fast go-karts. Learn how to catch a slide at age 10, and it'll be permanently burned into your synapses...
Scott G
12-17-1998, 10:13 PM
Also in understeer it is also wise to back off on your steering as well as the throttle. Most people will turn the wheel more when the car starts to push, this however is the wrong thing altogether. When you start to feel the push, back of the throttle a bit and let off on the steering a little (it may take only the width of a finger or three on the wheel to accomplish this. The movement of the steering is slight, that is if your not going too fast or catch it way too late), this allows the front tires to straighten out a bit to regain the optimum angle for traction. It is much harder to get the A4 quattro to oversteer as compared to understeer. Oversteer is more difficult to correct, especially as speed increases.
John/TSR
12-18-1998, 05:03 AM
then driving full size stuff fast is like driving a schoolbus at 20 mph. Karts the best training on earth....especially shifter karts.....oh my....oh yes.....oh baby.....shifters.....ooohhhhhh yeaaaaaaah<p>I expend what seems like 5-10 times the energy driving a car for 10 minutes than I spend driving a race car for an hour. I wish I'd had a fast cart as a kid.....but then again....I'd be broke or in jail by now.<p>Glad to see you're still among us, Mr. Slater. We were kind of worried that you'd been sucked up into some kind of "Heads-Up Display Hell", or actually were being forced to fly around in the hardware you build....<p>J/TSR
Greg Slater
12-18-1998, 08:53 AM
Oh, if you only knew how much time we spend in airplanes and simulators....<p>A good, full-fidelity full-motion training simulator for a 737 is a very fun toy, but going out and doing 30 to 40 near-zero-visibility approaches per day in a real plane makes a person weary. Still, it's better than sitting at a desk.