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Originally Posted by DaFish
No issues... I take what you say at face value... bring it on.
"What is "Understeer"?
Let’s say that you are driving on an icy street. You are going straight, but there is a corner coming up, so you turn your steering wheel. You turn it as you would normally, but your car just barely begins to turn.
This is called Understeer.
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WRONG. This is called corner entry understeer. It means the car does not respond to steering input prior to entering a turn. There are multiple ways to cure this. First, is human error. You are entering the turn too fast for the given amount of traction available to you. To cure it, simply enter the turn at a slower speed.
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Originally Posted by DaFish
Basically, the term Understeer means that you have to give your car more steering input than the corner should require to get it to go around. The advantage of this is that your car is usually very stable in a straight line, but you have to work harder to get the car to turn.
For a more scientific definition, imagine that we draw a tangent line to the circle that the car is traveling around. If you have to turn the front wheels so that they are at a more aggressive angle (pointed more to center) than the tangent line, your car tends toward Understeer.
Here’s another way to think of Understeer. If you are driving around in a circle of constant radius, and you start accelerating, your front tires will be the first to lose traction, which will increase the radius of the circle."
The passage above I copied from:
http://flatironsrally.typepad.com/fa...s-underst.html |
It's on the internet, therefore it must be the truth...
S.I.G.H.
There you go. You have little to no concept of what "understeer" actually means. What you've quoted, is a "text book" example of what understeer's symptom is. If I were to trying to describe understeer to someone who has absolutely no concept of what understeer means, that is what I would use.
It's the equivalent to, say, someone who has never watched or played baseball, and trying to explain to them why you shouldn't swing at every pitch. Well, the goal is to hit the ball somewhere, right?
There are multiple REASONS why understeer occur. At multiple locations of a single TURN. And the way to "cure" it will differ in every situation for every turn at every location. There is no simple "cure" for understeer. THAT, is what you don't understand and why I can't explain to you how to cure your understeer. The plain and simple truth is, a suspension system and how a car behaves at the limit of traction is dynamic, meaning there are multiple variables at work here.
Starting from the most simple and most basic, 99.95% of "understeer" is human error. Once you fix that part, the rest of the .05% of understeer can be fixed in the following manner: Add grip to the end that looses grip first, or take away grip from the end that still has it. And then, you have to figure out if the understeer happens at corner entry, corner exit, under throttle and HOW MUCH under throttle. If you can pin point where and when it's understeering and how, then you have a shot at fixing it.
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Originally Posted by DaFish
This is exactly what I experience. "front tires will be the first to lose traction, which will increase the radius of the circle"
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I'm going to try and explain to you something about chassis dynamics...I've tried to do this multiple times on various forums, and I've come to the conclusion that this is something impossible to grasp over a screen with me typing on a keyboard. So this WILL be the last time I ever attempt this. If you don't get it, I understand. This is something that can only be taught ON A SKID PAD and no amount of reading will ever replace actual experience with someone in the passenger seat pointing out to you what chassis dynamics is, weight transfer means, and when you're actually really understeering.
ALL CARS, no matter how well it's set up, will move away from that centerline tangent when you add throttle. ALL. Every single one. It's a simple physical law that can not and will not be defied in this universe. Acceleration force can only be applied in a straight line, when you're in a static circle, increasing your speed without adding steering will simply result in that static circle becoming larger, since acceleration forces will simply push you away from the apex.
That, is NOT understeer. It's the reason why Earth orbit around the Sun in a fairly consistent distance. If an external force is to be exerted on Earth to speed it up, the radius of the orbit will increase. It is what it is. Doesn't mean Earth is understeering from the Sun. In order to keep the same radius as Earth speeds up, another external force will need to be applied perpendicular to the orbit to keep the same orbit.
What understeer (or oversteer) REALLY is, is when NO AMOUNT OF STEERING INPUT will change the direction of the car. Meaning the front tires are now in a state of kinetic friction in relation to the ground. Meaning that you can no longer travel in a curve in relation to the turn, and the car basically will go in a straight line no matter how much steering input you give it...Not at least until the car slowed down enough for the front tires to regain traction.
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Originally Posted by DaFish
1) I have a 270 degree on ramp I go around all the time.... smooth, fast, no cops.... beautiful.
- I go in quick - possibly too quick - but no initial understeer as described above and the car is on balance.
- around 90 degrees the front push starts and continues into the corner. I try to keep acceleration neutral, not pushing with the larger rears (which I think is the prob). I feel the front tires fold over and that is when I lose even more traction, and the front steering wheel angle has to be increased to keep line. I have to back off speed to regain line when front grip returns. This is "fun killing, speed killing. I want this fixed.
QUESTION: Will a front strut brace help this?
2) Corner entry - initially has understeer, I can feel the fronts slide - I maybe going too fast in as you mentioned. If I go slower in, and get the car set on the corner, I can hold more corner speed throughout.
I am talking about a 90 degree street corner... before I did the mods, the fronts would plow terribly, overwhelming the tires -at what I thought was a slow speed.
- This issue has been dramatically improved with the addition of my camber (over neg 2 degrees).
- I think with the new dinan sways coming, it will be better again - QUESTION: By how much?
- I think if I had more meat in the front and a square setup - it would be better again - E90Pilot thinks this is the fix - I agree but it is expensive.
QUESTION: Will a front strut brace help this?
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I'm going to answer your last question first. You WILL be offended. I'm not going to sugarcoat anything.
No a strut brace won't help you. What will help you is some advanced driver training or high performance driving schools.
What you have described is a classic case of "fast in, slow out." You have to kill your corner exit speed because your corner entry speed is too high. The faulty part here, is the actual driver, not the car. More camber or more tire up front will only improve speed through the middle part of the turn and at the exit, but when you have already blown the corner entry, nothing you do will improve upon mid corner speed and corner exit speed. If you can't maximize mid corner speed and corner exit speed based on your current set-up, no amount of tinkering will ultimately solve your "understeer" problem, because as your speed picks up due to the modifications, you will still ultimately find your limit upon corner entry and run out of skill/talent, except when this happens, it'll be at a much higher speed, a speed you're not familiar with and will not be able to correct.
I am going to leave you with one final nugget of wisdom, because I don't think I'll ever be able to get through to you. Your car, as is right now, is far more neutral and far more capable than you ever will be able to take advantage of without some proper training. The more grip you actually add to your car, will only move that limit up that much higher. The end result will be that it'll come a time where you will have exceeded it's grip limit and when that time comes, you will destroy your car. It's not a pleasant thing for me to say, but it will happen. And when it does, I hope the passive safety systems on the car will keep you alive.
Actually I'll leave you with two nuggets of wisdom. I used to have a buddy who played some minor league baseball. One time we went to a batting cage, and he was stroking 90+ mph pitches easily. I mean it looked so easy so I ask if I can give it a try. Out of 20 pitches I fouled off one, and it made my hand hurt like a motherf**k. Heck I moved over to the 70 mph slow pitch stuff and maybe connected a couple of times for weak ground balls. So we got to talking about the "fine-art" of hitting a ball, and he was telling me that my form and swing actually looked okay, but the part of hitting that takes effort, training, and doing it on a daily basis, the hand/eye coordination, the anticipation, the weight transfer from the leg to the hip to the arm then wrist, the timing...etc, none of that can be learned by just watching. And that when it comes to REAL pitchers, once they started locating pitches and change speeds, it becomes 100X harder to hit.
Driving, especially performance driving, is a lot like that. Except the risks are much higher.
Actually, screw that. I'm going to give you one more nugget of wisdom. I'm kind and generous like that. If and when you actually comprehend this one, you'll have at least made it half way to curing your understeer problems. Your problem, is you move your hands too fast. Slow down your hands, start turning earlier, but turn the steer wheel slower, will cure UNDERSTEER.