WHEEL TALK

What is camber and how do you know if a vehicle has its toes tucked in? It's My Classic explains the jargon.

CAMBER

Assuming that your car or van is parked on a level surface, camber is a way of describing the vertical position of the wheels relative to the road surface.

 

Although one might assume that a wheel and tyre is going to be perfectly upright, actually there is frequently some degree of camber designed in.

Camber can play a significant role in your vehicle's handling and stability, especially when cornering.

Positive camber can help to make a car more stable, improving the ride quality and handling. However, a negative camber is often preferred for high performance and race cars as it can help to counteract the tendency of a tyre to roll onto its shoulder during high speed cornering. Negative camber helps to keep more tyre on the road surface.

What is positive camber in a classic car
Positive camber

On the flip side, too much negative camber can encourage your vehicle into really bad habits such as following tramlines or other imperfections in the road. It also tends to wear tyres out faster than a positive camber.

What is negative camber in a classic car
Negative camber

Excessive use of either positive or negative camber can have a detrimental impact on your vehicle and its handling. Unless you really know what you're doing, it's usually a good idea to leave the camber as it was designed.

TOE

In essence, toe is all about the symmetrical angle that the wheels make relative to the long axis (centreline) of the vehicle.

Toe impacts significantly on tyre wear, straight line stability and handling when entering corners.

Toe in (or positive toe) is where the front wheels point in towards the centreline of the vehicle. Toe out (or negative toe) is where the front wheels point out or away from the centreline of the vehicle (see diagram). Toe is measured either as an angle of deflection or as a linear measurement.

Toe out is uncommon on a road vehicle as it tends to make them more fidgetty, less compliant at holding a steady line, and in need of constant adjustment. These are less than desirable attributes for a road car, but can be preferred in a race car as it can increase the vehicle's turning speed.

In rear wheel drive vehicles in particular, some degree of positive toe may be preferred because of its greater straight-line stability. However, positive toe can result in less crisply positive cornering.

What is toe in on a classic car
Positive toe
What is toe out on a classic car
Negative toe

Too much positive toe (toe in) will result in excessive wear on the outer edge of the tyre, whereas too much negative toe (toe out) will show as excessive wear on the inner edge.

 

Toe is very much like camber in that there are many factors to consider when deciding on optimal set-up .

Then too, toe and camber can influence each other. It comes down to geometry, angular deflection, torque, static and dynamic loading, all compounded with desirable handling characteristics. There are loads of places on the World Wide Waffle where you can find details of the why's and how's if you want to delve into this in more depth.

CASTOR (or CASTER)

Castor is the degree of tilt of the steering axis or pivot. Perhaps the simplest way to visuallise it is to look at the front forks of a motorcycle. The angle at which they join the front wheel relative to vertical and the direction of forward travel is essentially the castor angle.

If the forks came down absolutely vertical, that would be described as a neutral (or zero) castor angle. Motorcycles have a positive castor angle.

 

Positive castor improves straight-line tracking and helps keep your vehicle on the road at speed and during cornering. The downside of positive castor on a vehicle without power steering is that the steering will be heavier.

Negative castor does make the steering lighter but can increase the tendency of a vehicle to "wander" on the road.

On motorcycles, castor angle is more commonly referred to as rake angle or head angle.

Castor tends to have limited impact on tyre wear.

Positive castor angle
Positive castor
Negative castor angle
Negative castor

This has been a whistle-stop overview of the subject of keeping wheels on the ground and you on the road.

 

If you would like to delve into this in more depth, try searching online for additional subjects such as thrust angle and steering axis inclination.

1938 Oldsmobile front suspension. Image courtesy of the New York Public Library Digital Collections
Oldsmobile knee action front wheel suspe

It's My Classic - the free online classic car and motorcycle magazine for people with a passion for heritage vehicles.