How does the principle of Ackerman Steering affect the cornering ability of your rc vehicle.

The principle of Ackerman Steering is the relationship between the front inside tire and front outside tire in a corner or curve.

It is the term used to define the steering geometry where the inside tire needs to turn tighter than the outside tire. This allows both tires to roll around a common point in a corner or curve. This can greatly improve cornering ability and performance. When doing any rc suspension tuning it should be one more thing to consider.

Rudolf Ackerman discovered and defined this principle early in the 19th century. Since then Ackerman Steering has had a huge impact on many different vehicles.

Ackerman Steering is used on all sizes of vehicles from full size down to scale models, no matter if it is 2wd or 4wd.

Some refer to Ackerman as the degree of toe-in or toe-out a wheel or tire has. Ackerman does have a relationship with the amount of toe-in or toe-out on your rc vehicle.

But, Ackerman Steering deals with the angle of inside tire and outside tire in a corner or curve relative to the degree of toe-in or toe-out. Will that is about as clear as mud. Let see if we can clear it all up.

In all the examples and photos below are for explanation purposes only.

Their only purpose is to explain the general principles of both parallel arm steering and Ackerman steering.

With the suspension on almost all rc vehicles being very complex it is impossible to give exact setting as to toe-in or toe-out and any Ackerman setting.

With so many factors, surface, tires, 2wd or 4wd, degree of toe-in or toe-out, driving style, etc..., that come into play it is up to you to find just what settings work the best for you.

But, understanding the principles can make it much easier to find the combination that works the best for you.

With parallel steering arms, the steering arms are parallel to the sides of the rc vehicle.

With any steering input both front tires will move an equal amount. This will cause the inside tire to slide or "scrub" through the corner or curve. With the inside tire scrubbing in a curve has many ill effects, heat build up, excess tire wear and traction loss.

This will result in your cornering ability to be twitchy and unpredictable. If you are using a parallel steering arm setup you can play with toe-in and toe-out to help to eliminate this problem, but it will always be present.

The best you can do is find a setting that works for you. With the front tires always turning equal amounts you just have to learn to live with your inside front tire scrubbing in a corner. No way around it.

With your steering arm angled towards the center of your rc vehicle will result in your tires angling at different degrees in a corner or curve.

Using Ackerman Steering your inside tire will be angled more in a corner than your outside tire.

With your inside tire needing to follow a smaller arch than your outside tire, this difference in angle will reduce or eliminate scrubbing. As you enter more steering input increases this difference in angles. More angle to the inside tire than the outside tire.

This example is just that, the amount of travel of your front tires depends on the steering geometry of your rc vehicle.

The amount of travel will vary depending on many different things, servos, steering arm lengths, tire size, type of front hubs, type of control arms, and etc...



Now let us look at Ackerman Angle: Regarding rc vehicles Ackerman Angle is referred to True, More or Less.

True Ackerman angle is when a line drawn from the center both king pins or pillow balls through the steering arm mounting points intersect on the center line of the rear axle.

More Ackerman Angle is when these lines intersect in front of the rear center line.

While less Ackerman Angle results in these lines intersecting behind the center line of the rear axle.

When you combine toe angle and Ackerman Angle together you can get some interesting results.

1. Zero toe (wheels pointing straight ahead) and True Ackerman will result with both tires being aligned with the circumference of the circle or arch of corner. Refer to the photos on the right.



2. With toe angle set to out and True Ackerman will result with both tires being toed-out equally relative to the circular path that they are following. Refer to photos on the left.

1. With toe angle set to in and More Ackerman will result with the outside tire being toed-in relative to the circular path and the inside tire running parallel to the circular path they are following. Refer to photos on the left.

There are no carved in stone rules as to which settings you need to use for what conditions. A lot depends on your driving style, tires and many other suspension settings.

As a general rule Ackerman Angles will have these net effects:

More Ackerman
1. Steering response will be smoother.
2. Your rc vehicle will react smoothly to any steering input.

Less Ackerman
1. Initial steering response will be more direct.
2. Your rc vehicle will react faster to any steering input.



If you are running a parallel steering arm setup in your rc vehicle and are looking for better handling and performance, you should consider changing over to Ackerman Steering.

With the number of adjustments that Ackerman Steering offers it can make huge improvements in your handling.

Almost all manufacturers offer Ackerman Steering as a hop-up option for many of their rc vehicles.

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