Delphi’s
Technology Tip
of the Rally:
Brakes

No stranger to tourists, spectators both home-based and abroad are expected to come out in droves to this weekend’s rally - and are they in for quite a show with the challenging gravel and asphalt surface variations.

With rally drivers known for their unique and skilled left-foot braking techniques, a mixture of the driver’s pressure on the brake pedal, precise steering control and the right parts can help to determine a driver’s success regardless of the terrain and/or weather conditions. Everybody knows rally cars go fast - very fast - and it’s the brakes that help slow the vehicle down and aid in driver control.

As the only mixed surface rally on this year’s calendar, one day taking place on mostly gravel and two days of asphalt driving, there are extra challenges facing the teams. This is especially true for the technicians and engineering teams who must convert the cars from gravel to asphalt specifications quickly and effectively.

On gravel surfaces, rally car brakes are very similar to everyday vehicles. Like passenger vehicles, WRC rally cars have two sets of brake discs, calipers and pads for these mixed surfaces - standard sized brake discs, calipers, pads and accessories for gravel driving. But they also have specialised discs, calipers and pads for tarmac surfaces, which are significantly larger and much different than their standard vehicle equivalents.

On asphalt surfaces, the car has much more grip on the road, and is therefore able to reach much higher speeds, necessitating a greater amount of braking. In this particular rally the stage changes from gravel to tarmac very quickly, and to keep the rally car safe on the varied surfaces mechanics need easy and quick-to-fit braking parts and accessories.

Taking a closer look inside the brake assembly, a WRC caliper has four pistons called “pots,” which apply pressure to the brake pads, and in turn grip the discs and slow the rotation of the wheel. Braking at high speeds can lead to heat generation of up to 610 degrees Celsius! Braking and steering are two areas where the rally vehicle should not fail. If the braking parts are not designed and manufactured to withstand extremely high temperatures, speeds and varying terrains, this could lead to premature failure. This is why it’s important to use the highest quality, durable parts, specific to the stage surfaces and fitted to exacting specifications.

Everyday drivers also want to feel secure when it comes to their braking systems. Delphi’s range of braking parts and accessories are known for their OE-matching quality, and in many cases outperform original equipment parts when it comes to stopping distances and performance in various weather and road conditions. Delphi conducts stringent laboratory and dynamometer programmes, as well as extensive real-world testing including Alpine and high speed trials, to help produce durable, safe and long-lasting braking parts.

As the official automotive technology partner of the WRC, Delphi offers an extensive range of braking parts and accessories comprising of brake pads and discs, brake shoes and drums, calipers, hydraulic cylinders and hoses.

To learn more about Delphi’s original equipment technology, visit www.delphi.com/am.

Follow these links to read the other Technical Tips in this series:

Cooling
Steering
And
Shock Absorbers