How does brake traction control work and do I need it?

When it comes to maintaining traction off-road, brake traction control can be your best friend. We explain what it is, why you need it and how it works.

You’ve probably heard the term ‘traction control’ but did you know that term covers two different types of electronic driving aid, and is related to a third? Confused? Don’t be, let me explain.

Brake Traction Control: both front and rear axles on a 4×4 have differentials, which allow the two wheels on the axle to turn at different speeds around a corner, yet both be driven. This is great for cornering, but not good off-road. The reason is when off-road the two wheels on an axle often have very different traction, for example one may be in the air and the other on rock.

In that case, the wheel in the air would spin uselessly when the wheel on rock would do nothing. Vehicles with Brake Traction Control detect the spinning wheel, and apply a braking force to that wheel only. This has the effect of increasing the torque (turning force) on the wheel with traction (on the rock) and forwards you go. As an example, the Ford Everest in the title image has no weight on the right front wheel, and lots of weight on the left front, so the computers are braking the right front wheel which will increase torque on the left front, and the car will move forwards.

Engine Traction Control: this is when vehicle has multiple wheels spinning, and the computer detects that and reduces the engine power to reduce wheelspin.

Electronic Stability Control (ESC): this works by detecting the vehicle either understeering (ploughing straight on) or oversteering (back end sliding out, see our Oversteer Recovery article). The computers then brake one or more of each of the four wheels to bring the vehicle back under control. For example, if you’re trying to turn left and the car understeers, then the computers might increase the braking force on the left wheels and reduce it on teh right to pivot the car into the corner. The computers may also reduce the engine power at the same time.

What’s best when?

When a 4×4 is off-road, brake traction control is beneficial. Why? It doesn’t slow you down as it only brakes a spinning wheel, and the effect on brake wear is minimal as you’re just braking a wheel, not slowing the entire car. Brake traction control is a sub-set of electronic stability control so all new 4x4s have it, and you definitely want it for off-road driving.

Both engine traction control and stability control do get in the way when offroad as they kill momentum, especially in slippery conditions such as mud, sand and snow. Generally, both are disabled or reduced in sensitivity when a 4X4’s offroad modes are engaged, for example a part-time 4×4 put into 4×4, or a centre diff locked, or low-range engaged.

Watch the video below which explains and shows how Brake Traction Control works. And stay tuned, we have more explanations coming soon.

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