Brake Discs

The mechanical and thermal stresses acting on the brake disc are extremely high. So it’s important they’re up to the job, and perform just as intended. Like all of our braking products, our discs are made to mirror the OE. So whatever the technology, you can be assured that every Delphi disc has been designed, engineered and manufactured to provide the very best braking performance. Just like the OE. Be it coated, cross drilled or high-carbon…it’s a given.

ECE R90 certified brake discs

It should come as no surprise that our brake discs for new vehicles launched post 1 st November 2016 are R90 certified, alongside a range for popular older applications. After all, we’ve been meeting these quality standards for many years. The only difference today: our discs now undergo official ECE R90 testing schedules including performance, dynamic friction comparison, high load integrity and thermal fatigue analysis to certify that they perform to a prescribed tolerance of the OE part.

Learn more about Delphi’s R90 certified brake discs and why it matters.

Fully coated brake discs

Thanks to a special zinc-flake, silver Geomet coating, our coated brake discs offer greater and longer-lasting corrosion protection compared with many oil-dipped or partially painted and coated equivalents, whilst also being more cosmetically appealing. And because they have no oil to clean off, they save valuable labour and service time. All this makes for a better protected disc that’s easier to install, easier to dismount as well as being easy on the eye too.

Read more about Delphi’s coated brake discs.

High-carbon brake discs

The added carbon content in our high-carbon discs helps to both reduce the risk of thermal cracking under high-temperature loads, and allows the discs to operate at a cooler temperature, for a more consistent braking performance. It also increases their resistance to distortion or warping for added durability, while delivering noise and judder free braking.

Cross-drilled brake discs

As well as looking cool from behind your wheels, our cross-drilled discs will keep your brakes feeling the same way – cool. The cross-drilled holes dissipate heat, brake dust and gases, helping to keep the pad surface cool and clean and reducing the risk of thermal distortion and warping. These same holes also prevent a film of water forming during wet conditions for improved braked response.

Vented brake discs

Our vented discs feature special internal cooling passages to maximise airflow. By continually moving air across the disc’s surface or through the disc itself, they allow more heat to be dissipated, improving both cooling capacity and resistance to cracking from thermal shock.

Brake discs with bearings

To avoid damage to the bearing during removal, and ensure the correct pressing in into the new, we offer a range of discs with these safety critical components already pre-mounted. They also include both toothed and magnetic ABS sensor rings, as per the OE, and the relevant fixing accessories. All for quick and accurate installation.

One-piece cast iron brake discs

Our one-piece cast iron discs offer an aftermarket alternative to BMW’s patented two-piece bi-metallic composite disc. Engineered from a single piece of cast iron, they deliver the same standards of consistency, longevity and braking performance as the two-piece disc, but at a fraction of the price. And to top it off, they come with fixing screws for quicker and easier fitting.

The Delphi Difference

  • 100 years of OE experience, supplier to the world’s top automakers
  • OE heritage and knowledge built into every aftermarket part
  • Comprehensive portfolio for a wide range of vehicles and model years
  • Streamlined SKUs for easy inventory management
  • Support through tools, tips and training

Related product resources and downloads

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Braking 4 min read

What is brake fade and how to prevent it

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Braking How to DIYers Drivers Technicians 4 min read

Look up ‘fade’ in the dictionary and it says ‘to gradually grow faint or disappear’ – not something you’d expect to hear in the same sentence as a safety critical component such as brakes. However, brake fade is an issue. And although more commonly associated with street or track racing, it can happen to regular cars too, especially when braking from higher speeds or under load. Because of this, it’s important to understand what causes it, and importantly, what you and your customers can do to prevent it.

What is brake fade?

Brake fade is a temporary and sudden reduction in braking power, caused by excessive heat in the system from braking repeatedly, under high loads or at high speeds. Unlike brake failure caused by a mechanical or hydraulic fault, the system is normally in good working order, and brake power will return, albeit not necessarily to the same level, once the issue has been addressed.

What causes brake fade?

In simple terms, brakes function by converting kinetic energy into heat. Every time the brakes are applied the system will generate heat, which under normal driving conditions, will dissipate into the atmosphere and other components once released. However, since kinetic energy rises with the square of velocity, braking from higher speeds or under load puts an exponentially increased demand on the system, generating significantly more heat. This excessive heat can quickly build up in the system, which if not dispelled effectively, can result in brake fade.

Types of brake fade:

Before we look at ways to prevent fade, it’s important to understand that there are different types of brake fade:

Brake pad fade:

Every brake pad has a maximum temperature range. When operating outside of these parameter’s, the frictional material effectively starts to degrade, causing the resins that bind the pad compounds together to out-gas, and in turn, creating a thin layer of high-temperature gas between the pad and disc. This new film causes the pad to essentially skid off the disc, temporarily reducing pad to disc friction coefficient and therefore braking power.

At these higher temperatures, the brake pads can also transfer a thin, uneven layer of friction material onto the surface of the disc. As the pads rub on the now uneven brake disc surface, they can create irregular heat build-up across the disc. If the temperature in these areas exceeds 650°C, the cast iron changes structurally and transforms into a hard material called cementite, creating high spots which can lead to brake judder and premature disc wear.

Green or early life brake fade:

New brake pads release gases the first few times they reach high temperature, and just like pad fade, create a loss of friction, known as green or early life fade. The good news is that green fade can easily be avoided by bringing the pads up to high temperatures under controlled conditions – a process known as bedding in the pads. This allows the two mating surfaces to transfer a layer of friction material to each other – pad to disc and disc to pad – in order to seat together and deliver optimal braking performance from new. Unlike pad fade, this even friction material transfer is beneficial after new pads have been installed.

Brake fluid fade:

For brakes to operate correctly and the brake pedal to remain solid, brake fluid must remain incompressible. However, if the fluid boils from prolonged or heavy braking, any moisture in it will also boil and turn to vapour. Since vapour is easier to compress than liquid, the brake pedal will eventually travel all the way to the floor, resulting in reduced, or even no braking power – pumping the brake pedal in this situation will help to regain some of it. To make matters worse, over time brake fluid absorbs water – as the moisture content of the fluid increases, the point at which it boils decreases, making the risk of brake fluid fade greater. If your customer has experienced fluid brake fade you’ll need to bleed flush through the brake fluid from the calipers until you get clear brake fluid.

Preventing brake fade:

For high performance or loaded vehicles, fitting components that are engineered to handle the additional braking demand is critical. Take our brake pads as an example. With a choice of more than 130 different friction ingredients, the friction material is especially formulated for the vehicle it is designed to fit. And our brake discs feature proven cooling technologies such as directional vents and cross drilled holes to improve both their cooling capacity and resistance to thermal shock.

Likewise, technicians should always perform a full road test in a safe environment to properly bed in the pads and discs, with 10 repeated stops at 60 percent braking effort, from 60mph to 20mph. During this procedure try to avoid heavy 100 percent braking or activating the ABS, and never leave your foot on the brake pedal to avoid stopping fully.

There are also some simple measures that your customers can take to minimise the risk of brake fade…and at the same time save fuel and reduce wear and tear:

  • Avoid riding the brakes as repeated use can easily overheat the system. 
  • Where possible, avoid heavy braking. 
  • Slow down – the faster you drive the more work your brakes will have to do.
  • Anticipate the need to slow down by thinking ahead.
  • Lighten the load in your car – more weight means the brakes have to do more work to stop your vehicle.
  • On downhill descents, especially if towing, change into a lower gear and make use of engine braking instead. If this is not enough, pull over and let the brakes cool down.
  • Replace brake fluid as per the vehicle manufacturer’s recommendation to reduce the risk of degradation.
  • Remember to bed in your pads if your garage hasn’t already done this

Offering simple advice like this, is a great way to demonstrate your new-found technical expertise and build lasting relationships with your customers, that like Delphi brakes, will never fade. Learn more about our brake pads.

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