Suspension problems - help me!!

  • Thread starter Thread starter yyanevans
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I'm totally confused about suspension!!

In 'M-Spec’s Pocket Guide to GT3 Suspension Tuning' (see GT3 settings and tunings), it is suggested that if you make one end of your car softer, it will get better grip. Therefore, if you have understeer problems, make the front softer.

It also says that you can decrease the front brake balance to prevent tyres locking up, thus preventing understeer.

Does this all sound right?

So, what I don't get, is why do front wheel cars have a tendency to understeer. If the
power is at the front, don't they have more grip at the front, and should therefore not understeer? And the vice versa for rear wheel drive cars?

Would be wicked if someone could put be straight one this.

Tanks alot,

yyan
 
Originally posted by yyanevans
So, what I don't get, is why do front wheel cars have a tendency to understeer. If the
power is at the front, don't they have more grip at the front, and should therefore not understeer?

since it's front wheel drive, the front tires LOSE traction (grip) when the throttle is open. Make sense?

cars understeer when the front tires lose traction
 
Let me explain a thing called the traction circle. Imagine that the contact patch of your tire is a circle, and it represents the available amount of traction that you have for that tire. You can represent the force that traction can generate on the car by a line like a clock hand, stretching from the center to the edge. Do you understand how vectors work? If you want to make a slanted line that is a certain length, you can represent that as a line pointing straight up a certain distance and left or right a certain distance, like this:

answer17.gif


Don't worry about the formula, they're not relevant, it's just a diagram. You see that the angled line is made up of a horizontal and a vertical component.

Now, imagine the horizontal component is the force that is turning the car, and the vertical component is the force accelerating or braking. The amount of traction that tire has limits the length of the slanted line, because if that line gets too big, the tire slides. In other words, if the line gets long enough that it goes outside the traction circle, the tire slides.

So you can see that if you want to make the car turn more - if you want to make the line slant more left or right - that is going to take away from traction available to speed up or slow down. And vice versa. If you are using traction up by accelerating out of the turn, you will have less available to make the car steer.

The reason FWD cars understeer is that you are asking the front tires to do three jobs, not just two. Since they must steer and brake (like a RWD car) and accelerate, the chance is much greater that you will exceed the traction circle for those tires.
 
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