Anti-Roll Bars - What Do They Do And Do I Need A Bigger One?

Anti-roll bars.

Some have never heard of it, others swear they need yet stiffer ones.

But really what is this piece of metal that we don’t see and yet comes up every so often at a car lovers’ meet?

We first explain the term roll, since the name of said metal bar is to oppose said roll.

Roll is essentially the clockwise / anticlockwise movement of the car’s body due to dynamic forces acting on the vehicle when in motion.

Picture: Barry Hayden

If you were to imagine going round a left bend quickly, you might notice the car leaning off to the right as centrifugal force pulls the car towards the outside of the bend, which in this case, is towards the right side.

Roll can be negative in the sense that it causes the car to be unbalanced. Using the same left bend example, if you went around that same bend quickly enough and the car rolled hard enough, because you know, the faster you go the harder you’ll roll, the car will likely end up with your left side wheels off the ground and heading towards a tree.

ohh anti roll bars are good then! I will have 2... no how about 3!....

Well not entire, and we’ll explain why in a bit.

Roll is good? Then i shall have for myself, a spring rolllllll....

But before that, let’s get on with what the anti-roll bar actually helps to do in a car. Simply, it’s a U-shaped piece of metal which connects the left and right wheels, and in doing so, ensures that both wheels rise and lower more or less equally by way of transferring forces across the bar between the wheels.

This in turn controls body roll, by eliminating undue upward or downward movement when the car goes around bends or over undulations in the road where the wheels are subject to different vertical travel distances.

Picture: Barry Hayden

Additionally, by controlling the weight transfer through the anti-roll bar, handling characteristics can be tuned by suspension engineers to give the car the desired understeer or oversteer pattern depending on how the manufacturer wants the car to perform.

It’s important to note that not every car comes with an anti-roll bar. Some cars are equipped with a torsion beam rear suspension setup which in itself serves the anti-roll function.

To answer the question then, whether you need a stiffer anti-roll bar, the answer is typically no. This is also the bit where we explain that body roll isn’t necessarily a bad thing – having a bit of give to the car allows for a more comfortable setup, and predictable handling.

Stiffening the roll bars without making the necessary adjustments to the dampers and springs may result in completely unwanted handling characteristics that the manufacturer never intended, and it may result in a dangerous ride especially in inclement weather which can be exacerbated in a poorly set up car.

Picture: Audi

So before you think about modifying your roll stiffness, consider that your car has been optimally setup for everyday use by the manufacturer, and unless you or your workshop know exactly what characteristics you desire out of your car, leave it as it is to ensure a safe, comfortable ride.

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