Can I say at the beginning, this is by no means complete or even completely accurate this is supposed to be a 'cause and effect' type list and not a complete course is advanced suspension dynamics. My aim is to give the beginner or even a more experienced racer a general overview of what all the adjustments on their car do.Important note - The more load you put on a tire, the LESS grip it will have.

An initial note about tire behaviour. A tire doesn't just sit on the road, it rolls along. If you apply a side force to a rolling tire it will start to move sideways. The why of this is easier to visualise with a treaded tire. Imagine a brand new tyre with small, deep tread blocks (pro-line's road hawgs are a good example). Now imagine this tire rolling down the road, when the car starts to turn, the tread blocks touching the road will lean over. As the tire rotates, following blocks will land slightly further to the side than the previous block. This means that a tire can be moving in a direction different from which it is pointing without sliding. This effect is sometimes known as 'tread walk'. The angle between where the tire is pointing and where it is actually going is known as the 'slip angle'.

As you add more weight to the tire, the tread blocks start to 'fall over' rather than just lean, this tends to overload the edge of the block and results in greater slip angles. As the tread blocks snap back into place, they make a squealing noise.

Slick tires work the same way, but on a much smaller scale, imperfections in the surface of the tire 'grip' imperfections in the road surface much like gear teeth meshing. (Now you see why a wider tire gives more grip).

The inclination of the wheel when viewed from the front of the car. As the car corners, the tire will distort as the car tries to hurl itself into the scenery and four little bits of rubber try to stop it. If the car isn't running enough negative camber, the car will be riding on the outer edge of the tire, this will tend to gouge chunks of plastic out of the rim and usually the car will be 'lurching' horribly. Too much negative camber and you won't have enough tire on the road, this will lead to a lot of sliding, it will however, be a fairly smooth, predictable slide. You will also have a lot of wear on the inside of the tire. This may also lead to grip problems when accelerating or braking in a straight line. This isn't all there is to camber, due to suspension geometry, camber will change as the car rolls and the cars castor angle will change the camber as the front wheels turn.

More complicated than camber, and rarely adjustable. Castor is one of the most important parts of a car's handling, as a rule, the car's castor angle will dictate the 'character' of a car. Basically castor is the inclination of the kingpin from vertical when viewed from the side. Go get your car and pull a front wheel off. Every car will have some form of pins that enable the front wheels to turn. A line drawn between these two pins will be the castor angle. Turn the wheels to full lock. Look at the camber of the outside wheel, if your car runs a lot of castor, the outside wheel will now have a lot of negative camber, the inside one will probably have positive camber.

Looking back at the camber section above, you can see that too much negative camber will lead to a smooth predictable slide. Or nice controllable under steer with excessive castor or even maybe horrible plow under steer in extreme circumstances. In some cases, reducing static camber will help with excessive castor, or, increasing static camber may help when you don't have enough castor.

Is this all there is to castor I hear you ask, of course not, it's a lot more complicated than that. This is just starting to get interesting. Now I want you to put your wheel back on and straighten the front wheels again.

Now we're going to do a little practical demonstration.

Put the car down on a flat surface and prop the back wheels about of an inch off the ground with a white board marker or something similar pointed along the length of the chassis. Turn the front wheels again, notice the way the car is now leaning? Notice that it is leaning out of the corner?

Pull the pen out and straighten the front wheels, measure the front ride height. Turn the front wheels and measure it again. Notice how it got higher?

That's the end of our practical demonstration. (Don't worry, I am going somewhere with this), The amount the car leaned and the amount it climbed are a function of two things, castor angle and wheel offset. If your car had what looks like heaps of castor, but didn't seem to lean or climb much, you probably have a Losi, (now you know why they have those weird wheels).

From our little demonstration, you can probably see how castor or wide offset wheels transfer weight to the outside rear wheel, when combined with acceleration and cornering forces, the outside rear is under a lot of load, often more than it can handle.

To summarize, more castor will give you less steering entering the corner (excess negative camber, weight forward) and more steering exiting the corner (car leaning out, weight transfer to back).

Set your steering to straight ahead and look at your car from above, if you can't see the wheels, take the body off. Now look again, are your front wheels pointed straight forward like | |? If they are, you are running very little toe-in. Are they pointed in at the front like / \? This is a LOT of toe in. You can also have toe out \ /.

Most of you have probably heard the rule of thumb that toe-in increases understeer while toe-out increases oversteer. This is generally true but it is not quite that simple. Let's take each end of the car separately.

The front tires initiate the turn, the rears follow. Therefore, what happens to the front tires determines the response of the car initially turning into the corner. Have you ever driven a car that feels good in the middle of the corner, but had to be literally thrown into the turn to get it to turn it? Less toe-in, or even a little toe-out would help it turn in. Why? When cornering, the outside tire requires a larger turning radius than the inside. In other words, the inside tire has to turn more sharply than the outside tire to get the maximum combined cornering force.

With the front tires toed-out, the instant you turn the wheel, this action of the inside tires turning more sharply than the outside already exists (Fig. 2). Both tires are able to provide the optimum cornering available. With front toe-in, the inside tire is constantly turned in, it is fighting the outside tire (Fig. 3) and detracting from the cornering power. This reduces the ability of the front end of the vehicle to turn into the corner.

Once the car does get turned into the corner, the weight starts to transfer from inside to outside, minimizing the affect of the inside front tire. Also, the rear tires are now contributing to the total cornering power and the suspension components are reacting according to their designs and setting.

It is possible for a car to not turn in or understeer initially because of too much to-in, and still oversteer in the middle of a turn, depending on all of the other suspension parameters. Obviously what you want is a car that is consistent throughout the turn.

If your car doesn't want to turn in, try a little front toe-out. It is a simple thing to do and is especially useful on tracks that have a number of quick turns. Keep in mind that toe-out reduces stability, creates drag on the straight-aways, and increases tire wear. (Note: My scanner is not currently hooked up. Look for figure's 2 & 3 soon)

Can be defined as an imaginary point that a car rolls around when it corners. Imagine you are looking at the back of a car as it enters a corner, as the car starts to lean, you can imagine a point the car is 'twisting' around.

The front and rear roll centers will usually be at different heights, you can use this as another tuning aid.

Firstly we need to determine the roll center height. This is usually easier to draw than to measure. Look at the back of the car, imagine a line traced along the upper and lower suspension links, unless these links are parallel, these lines will intersect somewhere.

Now imagine a line going from this intersection point to the center of the opposite tires contact patch with the ground. Where this line intersects with the center of the car is your roll center.

Keeping up so far, OK now things get complicated, as the car moves on it's suspension, the roll center will move, it even moves as the car rolls! So unless you want to calculate it for each possible combination of suspension positions, you will have to make some estimations.

OK now we have a pretty good idea of where the roll center is, how does it affect handling? There is one important relationship to consider, the distance between the roll center and the cars center of gravity (C of G). Under lateral forces (turning) the car will try to keep going straight, (Newton explained all this stuff) while the tires will try to turn; the sideways force acting on the car can be said to be acting at one point, the C of G. The forces resisting the car can be said to be acting at one point, the RC. The further these two points are apart, the greater effect the lateral forces will have on the suspension, or the more the car will roll. Theoretically, if the C of G was below the RC, the car would lean into corners like a motorbike! (Don't try this, it will be a bad thing)

So how do you adjust RC? It's actually fairly easy, if you look at it, if you lower the car 1mm, the roll center will actually move further. You may have heard people say that if you lower the front, it will put more weight on the wheels and the front will grip more. What actually happens, is that when you lower the front, the roll center drops further than the rest of the car, and this effectively softens the front suspension in roll, much the same as fitting softer springs. You can also adjust RC by moving the upper camber links around, which brings us to camber change.

This is actually fairly simple, if you look at the camber on the car, then compress the suspension all the way, you will see that you now have more camber. If you look at the way the upper link moves through the suspension travel, you can see that the shorter the link or the closer the link is to vertical, the more camber change you will get. Camber change is a very useful tuning aid, you will need to have some to counter the fact that the car rolls while cornering. If you have more, it enables you to have a small amount of camber when you're going in a straight line, and then have the car automatically dial in more when you're cornering. Problem, what happens when the car hits a bump? The car instantly develops heaps of negative camber, or when the rear drops into a hole it develops positive camber. Neither of which are good for traction. Basically running large amounts of camber change is OK if you're running on a smooth surface, with stiff springs.