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Discussion Starter · #1 ·
Ok I admitingly have never tracked a car except the drag strip with my old k04 s4. I bought the elise because i'd like to learn to track it but also because it's been a dream car many years of my life and it's just incredibly fun to drive regardless of being a pro or not. So as I read this forum i see things that I don't quite understand or get - terms people use, situations i have never experienced - etc - so here's a thread where people don't have to feel like an idiot for asking and all start!


What's snap over-steering?

also someone mentioned hitting a turn to hard letting off the gas and having the engine spin cause the car to go ass around? why is that?
 

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I am not experienced...I just read a lot. So if I am wrong about this please let me know. My dad owns a 2001 s2000. These are known for snap oversteer. Basically you are driving at the limit of the cars handling. You are on the edge and you just push it a hair too far. With no warning whatsoever you end up facing the opposite direction in a cloud of dust as your car flips around. In the elise from what I've read (no experience) there is more of a warning before your car snaps around and oversteers.

In rear wheel drive cars...especially mid engined, as the weight is centered more towards the back if you enter corners at a high velocity the car is balanced. When you hit the break mid corner, let off the gas, disengage the clutch mid corner the weight of the car transfers towards the front lightening the rear of the car. The rear wheels are now spinning with no load on them, the back end slides around and you end up facing the opposite direction. I believe people use letting off the gas to initiate drifting, you let off the gas then put it back on, but if I believe if you do this at too high of a speed you end up facing the opposite direction in a cloud of smoke.

Once again this is not from experience, i have just been reading. Take this with a grain of salt, and people please correct me if I am wrong
 

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P.S. Oversteer is different than snap oversteer. Regular oversteer can be perfectly safe if handled properly from what I understand. I have expereinced very little of it while driving my dad's s2000, as its not my car to play around with, and will not push it, or endanger it. In fact the little I felt of it I was going aroudn a corner and hit a slight sand spot, and felt a slight sliding sensation...perfectly controlled, no worries.
 

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Snap-oversteer is when you scream and then end up in a ditch. The tyres go beyond their handing envelope and wave goodbye to the land of grip. It's possible to catch it if you're quick enough.

If you lift off mid-corner all the weight that was over the rear of the car, keeping the rear tyres pushed to the road, then shifts to the front of the car meaning that everything keeping the rear wheels pushed to the ground isn't there anymore and momentum will make the back of the car overtake the front. Again, this can be caught if you're quick and it's often used deliberately to provoke the car in to going sideways for a laugh.

If sideways isn't your thing then may I recommend learning the art of trailbraking?
 

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Agent,

Check out Amazon... there's some excellent books that are great primers - sorta like "Racing for Dummies".

Caroll Smith - Tune to Win
Caroll Smith - Drive to Win
Alan Johnson - Driving in Competition
Paul Frere - Sports Car and Competition Driving

All of these cover the "jargon" and discuss the basics of high performance driving. Obviously reading a book doesn't replace actual practice, but it's a starting place, like doing ground school before piloting a plane.

Enjoy!
Kiyoshi
 

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Your car is in a state of oversteer if you're driving beyond the limit of adhesion in a corner, and your rear wheels lose traction first -- you "lose the back end," you "fishtail," your car turns MORE than you'd like it to.

You car is in a state of understeer if you're driving beyond the limit of adhesion in a corner, and your front wheels lose traction first -- it "plows," it "pushes," it turns around the corner LESS than you'd like it to. It goes in a straight line when it should be turning.

All this happens at the limit of adhesion.

"Snap oversteer" (in my opinion) is just a way of describing that the car entered an oversteer state quickly, violently, without any telegraphed warnings. It most frequently happens because you unloaded the back end of the car by quickly lifting off the accelerator mid-corner.

This occurence -- lifting off the gas mid corner, and losing traction at the rear tires -- is also called "trailing throttle oversteer" or TTO. It can lead to violent "snap oversteer," but can also be used as an effective way to increase cornering ability in tight, slower corners by "rotating the car."

You will also hear the term "power-on oversteer." This describes oversteer by INCREASING your throttle.

Finally, some people might also use the term "snap oversteer" to describe the "whipping around" effect of an oversteering car that is spinning out of control.
 

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Physics of Racing by Brian Beckman and other Books

The Physics of Racing is a series of articles written by Brian Beckman. If you have an analytical mind and are interested in gaining a gut feel for what your car is trying to do, this is an excellent online resource:

http://www.miata.net/sport/Physics/

The other book that I use as a bible is How to Make Your Car Handle by Fred Puhn.

While I am supplying a bibliography of interesting books, I also strongly suggest all(!) of Carroll Smith's books. He was the project engineer and team manager for Shelby during the Ford attack of Le Mans. Great reading about what works and what does not...

These books have helped me over the years and are a great way to learn about car handling and engineering.

Michael
 

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Jon did a nice job of defining "Oversteer" vs "Understeer". One fine point of correction... technically you don't have to exceed the limit of adhesion.

Oversteer/Understeer is a way of describing which end of the car (front vs rear) is closer to their limits. The term commonly used to measure how close a tire is to the limit is "Slip Angle".

The end of the car that is at a higher slip angle corresponds to Over/Understeer. If the front tires are at high slip angle (closer to the limit of the available traction) than the rears, then the car is Understeering and viceaversa. Neutral is when the slip angles of the front tires vs rear tires are equal.

What Jon described is what you experience. What I just discribed is the technical cr*p that doesn't mean a whole lot when you're going off the track *ss-end first! :D

Kiyoshi
 

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khamai said:
Jon did a nice job of defining "Oversteer" vs "Understeer". One fine point of correction... technically you don't have to exceed the limit of adhesion.

indeed, yes.:)
 

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Slip angles. The magic words :)

Go find a big empty car park and drive the Elise in a circle, keep the steering wheel at exactly the same point whilst doing the circle, don't make any adjustments to it.

Keep adding power and eventually you'll find the car's circle will get larger at the front tyres go beyond their slip angle and start to understeer.

Get back to doing normal circles again and then really dump on the power. You should get BIG understeer as the car should then go forward in a straight line even though the wheels are angled as you've gone well and truly past their slip angle.
 

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is it because of the slip angles that in everything I've read and seen it is more common for people to understeer going into a corner, and oversteer comming out? or is it because they add throttle as they leave a corner making the back slide out? or am i confusing stuff.
 

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Gasroth said:
is it because of the slip angles that in everything I've read and seen it is more common for people to understeer going into a corner, and oversteer comming out? or is it because they add throttle as they leave a corner making the back slide out? or am i confusing stuff.
Oversteer/understeer tendency of the car is dialed in. Most modern cars are set up to understeer. This is safer, since the natural tendency is to let off the gas when you're not going the way you intend to. This shifts weight to the front, adding front traction, decreasing the slip angle, correcting the understeer.

It's all about balance and the relative traction between front and rear. Going into a corner, if you trailbrake (means you only partly let up on the brake as you turn in), there is more weight on the front less on the rear, so the rear slides more and you "oversteer". You can also be standing on the brakes using up all the traction for braking, and turning the steering wheel does absolutely nothing and you "understeer" big time. Comng out of the corner on the gas, the weight is more in the rear less in front with consequent less traction, so you "understeer". If you have gobs of torque and HP as in the Viper or Z06, you can overpower the added weight and traction in the rear and break the tires loose so then you "oversteer".

A well balanced car can be rotated, or be made to understeer/oversteer, depending on throttle/brake appication. You can make in turn in more, or less, while keeping the steering wheel static. This is "throttle steering".

The best book for newbies is "Going faster! Mastering the art of race driving" by Danny Sullivan. It's the texbook at Skip Barber Racing schools.

Take the car to autocross and drive the car up to and beyond the car's and your driving limits. All this discussion is fine, but nothing like practical application to hammer it in. Then take the car to the race track for some high performance driving to apply what you've learned. It's a TON of FUN!!!.
 

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Discussion Starter · #13 ·
ok well since no one else has asked anything

can someone here explain the more exact mechanics behind the multiple cam situation in the car? what exactly happens when you hit 6000 - why does the torque shoot up and why can't it be like that below 6000 - now im not as dumb as i sound - im just curious how and why this all works the way it does...
 

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2ZZ-GE engine explained

There is a great writeup about the 2ZZ-GE engine, as found in the Elise, by Jeff Chan. It can be found on my website at:

http://www.sandsmuseum.com/cars/elise/thecar/engine/toyota.html#lotus tuning

I also strongly recommend: SAE Technical Paper 2000-01-0671 "Development of the High Speed 2ZZ-GE Engine" by Takasuke Shikida, Yoshikatsu Nakamura, Tamio Nakakubo and Hiroyuki Kawase, Toyota Motor Corp.

This is a paper submitted by some of the designers on how the cam works, how the engine fits in with the competition and even has stuff about noise suppression. SAE has strong copy right rules and wanted $1500 for me to host the document on my site. As an educational site, I could not justify the expense. You should be able to search for it elsewhere online.

Michael
 

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Palting said:
A well balanced car can be rotated, or be made to understeer/oversteer, depending on throttle/brake appication. You can make in turn in more, or less, while keeping the steering wheel static. This is "throttle steering".
The first of two excellent points in this post. So many people read the word "understeer" as though it's always a bad thing. A properly set up car should be neutral or have a hint of understeer, since oversteer is much easier to dial in and out with the controls (steering, brake, throttle) and can be dialed out with technique (line, smoothness, entry speed) as well. I'm sick of reading on car forums how oversteer is better than understeer. A well balanced car is the ideal.

Palting said:
The best book for newbies is "Going faster! Mastering the art of race driving" by Danny Sullivan. It's the texbook at Skip Barber Racing schools.

Take the car to autocross and drive the car up to and beyond the car's and your driving limits. All this discussion is fine, but nothing like practical application to hammer it in. Then take the car to the race track for some high performance driving to apply what you've learned. It's a TON of FUN!!!.
"Going Faster" is my favorite driving technique book, but some of it is a bit too technical for novices IMHO. Khamai already recommended Paul Frere's "Sports Car and Competition Driving", and I highly recommend that for people who are just getting into performance driving. "Going Faster" is great as a second book.
 

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My definition of snap-oversteer is based on experiences owning a '91 MR2 (sold, sadly). Several times, usually on off-camber corners, I'd push it too hard and experience a large oversteer condition. I'd correct, and the tail would swing back inline, then continue past the straight position until it's then swung out a little on the opposite side. Then...SNAP. Violently swings back to the outside. So, my definition of snap oversteer is violent and rapid oversteer encountered from a failure to smoothly recover from a regular oversteer condition.
 

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Rawr said:
Slip angles. The magic words :)

Go find a big empty car park and drive the Elise in a circle, keep the steering wheel at exactly the same point whilst doing the circle, don't make any adjustments to it.

Keep adding power and eventually you'll find the car's circle will get larger at the front tyres go beyond their slip angle and start to understeer.

Get back to doing normal circles again and then really dump on the power. You should get BIG understeer as the car should then go forward in a straight line even though the wheels are angled as you've gone well and truly past their slip angle.
He who is welsh and knocked you out has tought you well :up:
 

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agent orange said:
and what's the proper way to correct oversteer?
Mostly not creating it in the first place. You can steer into it and also add weight to the rear tires by more throttle.

If it gets past the point of recovery, then push in the clutch and brake and close your mouth.

To reduce the oversteer tendencies of a car, you can incease understeer (bigger front bar, skinnier front tires, stiffer front shocks), more toe in..... or by softening the rear, fatter rear tires, or more toe in on the rear tires.
 

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agent orange said:
and what's the proper way to correct oversteer?
I wish I knew. ;)

I *think* the trick is to catch the tail as it's swinging back inline, and prevent it from swinging much to the opposite side of the original swing. So, I think you need to counter-countersteer as the tail's getting close to straight, just a little nudge, nothing big. Hopefully someone more knowledgeable than I can chime in here?
 
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