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Oh... come on guys.....!
The meaning of the phrases Under Steer and Over Steer are built into their NAMES..... however, most people don't seem to think about that!
Put simply (without using OTHER synonyms for Understeer... like 'push'.....) UNDER steer is when an amount of steering movement (how far you rotate the steering wheel) does NOT result in ENOUGH change of angle of the kart (car) as you wanted. I.e., you turn the steering enough to make you change direction by (for example) 10 degrees but the kart only changes angle by 5 degrees.
Oversteer is the opposite: you turn the steering wheel to change the kart's angle by 10 degrees but you get 20, 30, 40, 50 (and so on) degrees of change of angle.
Undesrsteer is when you get LESS change than you wanted and Oversteer is when you get MORE change than you wanted!
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In more detail:
Understeer is when the FRONT wheels don't grip ENOUGH to change your direction as much as you wanted.
Oversteer is when the REAR wheels lose grip and start to move FURTHER away from your chosen 'line' than you wanted!
Cures
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In simple terms:
* cure understeer by INCREASING the front grip
* cure oversteer by INCREASING the REAR grip
There is a bit of a twist here! You might notice that we are talking about 'too much' or 'too little' grip... however, we haven't said 'too much/little'.....compared to WHAT????.
The answer to that is also simple! The concept of too much/little grip at the FRONT means.... in comparison to the REAR. Too much/little grip at the REAR means..... in comparison to the FRONT!
The concept here is the BALANCE of grip between the two 'ends'! When one set of wheels can overcome the other set, that's when you have under/over steer!
That offers us ANOTHER twist! Understeer is when the front has too LITTLE grip when compared to the rear. To cure that, you CAN increase the front grip (e.g., fit better tyres on the front). However, you could ALSO restore the balance between the two grips by REDUCING the REAR grip (e.g., putting WORSE tyres on the rear)!
However, you need to think CLEARLY about this (amazingly, most people DON'T)! I chose the 'change the tyres' example to illustrate the point....... and the silliness!
If you have lousy front tyres but good rear tyres which leads you to understeer..... it would be BONKERS to fit LOUSY rear tyres to restore a balance! It should be utterly OBVIOUS that you will simply corner SLOWER: karts with wooden tyres at BOTH ends don't corner THAT quickly..... The CORRECT solution (i.e., to improve your lap time, becasue that is EXACTLY what we are trying to do!) would be to IMPROVE the FRONT tyres.
I assume that EVERYONE can see that point....... however.........
You will hear LOADS of people say 'to cure understeer.... reduce the rear grip'......
Think about it.........
Yeahhhhhh....... that WILL reduce understeer but it will (often) HUGELY INCREASE you LAP TIMES!!!!!!..... for EXACTLY the same reason as replacing good rear tyres with wooden tyres in my above example would ALSO increase your lap time!
So.... as a matter of principle, you should try to cure BOTH Under/Over steer problems by IMPROVING the grip on the 'end' that has the POOR grip.... and NOT by reducing the grip on the GOOD end! No matter WHAT other people tell you! It's only when you have done EVERYTHING to improve the 'missing grip' that you sometimes HAVE to reduce the grip at the OTHER end to redress the balance.
Put crudely:-
* First choice: improve the grip at the 'sliding end'
* Second choice (if all else fails): reduce the grip at the GRIPPING end!
Having said that.... the most effective method of BALANCING the two-end-grips is by moving some weight forward or backward. (* see note at the end*) By definition, however, such re-balancing WILL be a matter of MOVING grip from one end to the other! By moving weight FORWARD to reduce understeer, you will have REDUCED grip at the rear simply because you have moved the weight (and thus: grip) from one end to the other!
You should by now be able to see that under/oversteer are really, simply, when there is an IMBALANCE between the grip available at the two ends of the kart!
Ian
* Note *
My example is NOT correct where you simply ADD more (for example) lead to the front of the kart to reduce understeer! That WILL increase the front grip without reducing the REAR grip...... However, you'd be BONKERS to increase the OVERALL weight of the kart where you don't have to!
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Understeer & Oversteer by 'Rocco' (07 Jan 2009 @ 9:12)
