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Diagnosing and Rectifying Disc Brake Rotor Issues – Advice from Bendix

Technical Bulletins

Apr 20, 2022

As a vital component of a vehicle’s braking system, discs or rotors, are an item that should be regularly inspected for wear or damage, to ensure ongoing braking performance and safety.

While this task will normally be undertaken by the local mechanic or brake specialist as part of a car’s regular servicing schedule, it pays for drivers to be mindful of the symptoms of brake rotor issues.

Given the extreme conditions that brake rotors work under, including extreme heat, high loading and exposure to water, dirt and grit coming off road surfaces, it’s possible for these components to become compromised over time and in between servicing.

An intuitive driver will likely pick-up some of the early indicators of rotor issues, allowing them to have the braking system checked by their workshop, to ensure optimum performance is restored as soon as possible.

A technician undertakes an inspection.

Here’s what to look out for and how to treat potential problems.

Disc brake rotor warping

Warping is where the rotor surface becomes uneven – normally it’s caused by excessive heat in the brakes. Through regular high-load braking situations, the rotors can become glazed from the brake pad materials rubbing off on the rotor at extreme temperatures.

Extreme changes in temperatures can also cause warping, for example heavy braking followed by submersion in cold water, such as might be experienced off road when four-wheel driving.

The symptoms of rotor warping could be as severe as brake pedal feedback during braking, jittery or inconsistent braking, vibration during braking, or more subtle indicators including excessive squealing when braking or a burning smell.

Checking the thickness of the disc brake rotor to ensure it's suitable for machining.

Depending on the source of the problem, the rotors can be machined, a process that uses a lathe to refinish the surface of the rotor, returning it to a flat surface. If the warping is too severe or the rotor is too thin (in the case of previous machining), the rotor will need replacing.

Machining the disc brake rotor to restore the flat braking surface.

Cracked rotor

In short, causes that can lead to rotor cracking are similar to those that cause rotor warping: excessive heat and extreme temperature changes – but also throw another element into the equation, the quality of the materials used in making the rotor, as well as the manufacturing process.

A rotor that does not have the correct metallurgy (the science of producing and purifying metal) will be more prone to cracking – a poor manufacturing process is also a major contributor to rotor cracks. Typically, cheap rotors that have had less development and manufacturing applied, will be more likely to crack.

For the driver, symptoms to look out for include low frequency vibration during braking and more intense braking shudder, depending on the size of the crack(s). The solution for cracked rotors? There’s only one: replacement.

The Bendix rotor range

As a specialist producer of braking systems and market-leader in this field, Bendix offers a range of rotor solutions to suit passenger cars and performance vehicles with its ‘Euro+ Disc Rotors’ and ‘Ultimate Sports & Performance Disc Rotor’.

These quality products have been designed and developed to exacting standards, using high quality feed materials and the latest manufacturing processes, reducing the likelihood of rotor warping or cracking.

Bendix car disc brake rotors feature High Carbon Metallurgy and SWIFTFIT protection.

High Carbon Metallurgy

Common to both ranges is Bendix’s Hight Carbon Metallurgy – this technology improves noise dampening characteristics and heat dissipation. The higher the carbon formulation, the better the rotor can withstand elevated operating temperatures; another benefit is higher wear resistance and durability, while reducing the chance of warping.

SWIFTFIT protection

For efficiency of installation (no requirement for pre-cleaning), Bendix rotors features ‘SWIFTFIT’ coating, an advanced protective zinc coating that helps to protect against corrosion. With uncoated rotors, corrosion can impact the rotor mating with the wheel hub face over time and create vibrations.

Drivers who suspect that their rotors may be suffering from warping or cracking, should organise an inspection of their brakes by a professional as soon as possible.

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