Common Terms Explained For RC Cars (Part 1)

Here are some of the common terms explained for RC cars. These terms and abbreviations are commonly used by experts, manufacturers, message board users, old professionals, racers, club members etc.

Ackerman refers to the angle between the two front (steering) wheels when turned to full lock. Altering this 'ackerman angle' will alter the steering characteristics. A greater angle will give you smooth, predictable steering, whilst a smaller angle will give you more aggressive steering.
The angle for the rear whish bone hinge-pins relative to the horizontal refers to the term "Anti-Squat". Increasing the angle gives more anti-squat, meaning that the car is less likely to squat (drop at the rear) during acceleration.

Wheelbase is the distance between the front and rear axles of the car. The angle of the wheels (when looked at from the front or rear of the car) relative to the vertical is known as Camber. If the wheels lean inwards towards the car, the angle is said to be negative. If they lean out the angle is positive, however, positive camber is almost never used. Basically, zero camber gives the maximum forward traction, whilst more negative camber gives more grip while cornering. Caster describes the angle (when looking at the front wheels from the side of the car) between the kingpin and the vertical. This is part of the car's geometry which keeps it travelling in a straight line when no steering force is applied. It is not adjustable on all cars.

The relationship between the speed of the motor and of the driving wheels is known as the Final Drive Ratio. For example, a final drive ratio of 8.17:1 means that for every rotation of the wheel, the motor rotates 8.17 times. Lower the number on the left of the colon, the higher is the ratio i.e. more top speed and less acceleration. Tweak is the difference between the heights of the wheels relative to the ground (at the same end of the car). e.g. If the front left is lower than the front right the car is said to be 'tweaked' usually caused by a distorted or 'tweaked' chassis or unequal shock lengths

Toe-in is the relative angle between the two front wheels or rear wheels (when viewed from above). If the wheels point inwards (towards the front of the car) it is called toe-in, if they point outwards, it is called toe-out.

When people refer to body roll, they are talking about the way the car pitches, either from side-to-side (when cornering) or front-to-back (when braking or accelerating). Ball differential is a design of differential unique to model cars which use ball bearings instead of bevel gears to achieve differential speeds at both wheels. It has the effect of allowing one wheel to slip whilst still delivering power to the other. It is also known as 'limited slip differential'.

Tires which have a flat ring of ridged material molded into the rubber to prevent 'growing' at high speeds, an effect that reduces the tires contact area with the track, resulting in loss of grip. This tires are known as Belted Tires.