Brake Slider Replacement: When and Why

Ensuring your vehicle's braking system operates at its peak efficiency is paramount, and this hinges on the free movement of its various components. Unfortunately, the harsh realities of environmental exposure, coupled with the aggressive nature of acidic cleaning agents and high-pressure washers, can lead to corrosion within the brake system. This corrosion acts as a significant impediment, hindering the seamless movement of critical parts. The consequences can range from the brakes overheating due to prolonged, unwanted contact to, more alarmingly, causing your vehicle to react unstably during braking, potentially leading to dangerous accidents. For a more in-depth understanding of how corrosion impacts braking systems, we highly recommend referring to our dedicated article on the subject.

Within any braking system, there are numerous contact points that necessitate careful attention during any repair process to guarantee unrestricted movement. There's a lingering, old-school habit prevalent in the automotive industry that elevates copper grease to the status of a universal workshop lubricant. However, the application of copper grease within the braking environment is far from ideal. It can actually instigate galvanic corrosion, a process that is significantly exacerbated when contaminated by acidic wheel cleaners. This contamination often occurs as owners strive to maintain the sparkling appearance of their alloys or rims. Therefore, the notion that a single type of lubricant is suitable for all contact points within a brake system is fundamentally inaccurate.

At Apec Braking, we are proud to offer a specialised slider lubricant that boasts compatibility with rubber components and possesses excellent moisture resistance. This dual-action formulation is designed to actively prevent corrosion. It is considered best practice to remove and meticulously examine the brake sliders during every brake pad and disc replacement. Seized sliders are increasingly becoming a prevalent issue, largely attributed to the growing prevalence of pressure washers. These powerful tools possess sufficient pressure to breach the protective rubber boots, allowing moisture to ingress into the slider cavity.

If your sliders are found to be in a poor state of condition, it is strongly recommended that they are replaced. However, if the sliders are deemed to be in good condition – meaning they are not pitted or bent – they must undergo a thorough cleaning process to remove any existing corrosion. Following this, they should be re-lubricated with Apec Caliper Slider Grease to ensure not only free movement but also robust protection against future corrosion. A common shortcut adopted by some technicians involves removing only one slider bolt and then swinging the caliper away to facilitate the fitting of a replacement pad. This method, however, is strongly discouraged. It does not permit a detailed examination of the sliders and crucially, it doesn't provide the necessary access for the thorough cleaning of any corrosion from the caliper carriers. Consequently, this shortcut compromises the integrity of the repair.

For contact points that remain exposed, such as the abutment points on the caliper carriers, a lubricant is required that will not induce galvanic corrosion with the surrounding metallic components. It is absolutely essential that the lubricant used possesses the correct consistency to prevent it from being displaced through the normal forces of driving or during cleaning procedures. For these specific contact points, our specially formulated, metal-free Apec Brake Grease, with its high melting point, serves as the perfect lubricant. It effectively prevents galvanic corrosion. Apec Brake Grease is manufactured using super-refined mineral oils, rendering it water-insoluble. This characteristic provides superior resistance against being washed away, even under the most adverse conditions. However, it's crucial to note that this grease is incompatible for use on slider pins. Its chemical composition can cause the surrounding rubber boots to deform, which in turn allows contaminants to enter the slider cavity and ultimately impede free movement.

Understanding the distinct requirements of different brake components is key to effective maintenance. The caliper slider pins, for instance, require a lubricant that is specifically designed to work in harmony with rubber seals, providing lubrication while also repelling moisture. This prevents the build-up of rust and ensures the caliper can move freely. On the other hand, the areas where the brake pads meet the caliper carrier (abutment points) experience different stresses and environments. These points benefit from a high-temperature, metal-free grease that can withstand the heat generated during braking and prevent metal-to-metal contact without causing galvanic corrosion.

Let's explore the 'why' behind different lubricants in a bit more detail. The primary reason for distinct lubricants stems from the materials involved and the operating conditions. Slider pins are typically made of metal and slide within rubber bushings or boots. A lubricant for these pins needs to be compatible with rubber to prevent degradation, and it must also resist water wash-out. Copper grease, while a good general-purpose lubricant, contains copper particles. When in contact with dissimilar metals (like aluminium caliper bodies and steel slider pins) in the presence of moisture and road salts, it can create an electrochemical reaction leading to corrosion. This is galvanic corrosion. Furthermore, the effectiveness of copper grease can be compromised by modern acidic wheel cleaners, which can break it down and exacerbate the corrosion process.

Apec Caliper Slider Grease, conversely, is formulated with synthetic base oils and additives that are specifically chosen for their compatibility with rubber and their ability to form a durable, water-resistant film. This film lubricates the slider pin, allowing it to move freely within the caliper, and also acts as a barrier against moisture and contaminants. The absence of metallic particles eliminates the risk of galvanic corrosion.

Apec Brake Grease, the metal-free option, is designed for high-temperature applications and areas where metal-to-metal contact needs to be prevented without the risk of galvanic corrosion. Its high melting point ensures it remains in place even under the intense heat generated during braking, preventing the pads from sticking or squealing. Its water-insoluble nature further enhances its durability in these demanding conditions.

Using the wrong lubricant can have severe consequences. Applying a high-temperature grease like Apec Brake Grease to the slider pins could lead to the premature failure of the rubber boots. The aggressive nature of such greases can cause the rubber to swell or degrade, creating gaps that allow water and dirt to enter the slider housing. This ingress will quickly lead to corrosion and seizing of the slider pins, defeating the purpose of lubrication and potentially causing more significant brake issues.

Conversely, using a lubricant that isn't designed for high temperatures at the pad abutment points might lead to the lubricant breaking down, evaporating, or being washed away. This can result in increased friction, noise (squealing), and uneven wear of the brake pads and discs.

To summarise the importance of correct lubricant selection, consider this:

The question of whether you need to replace your brake sliders is directly linked to their condition. If they are pitted, corroded, bent, or seized, then replacement is not just recommended, it's essential for safety. Even if they appear visually acceptable, a thorough inspection for smooth movement and the absence of damage is crucial. If sliders are found to be seized or damaged, it's often advisable to replace both the sliders and potentially the caliper bracket if corrosion has significantly impacted the bracket itself.

The frequency of checking brake sliders should ideally coincide with routine brake servicing, such as when brake pads or discs are replaced. However, if you notice any symptoms of brake issues – such as a pulling sensation when braking, uneven braking, sticking brakes, or unusual noises – it's wise to have your brake sliders inspected immediately.

In conclusion, maintaining the integrity and free movement of your brake sliders is a critical aspect of your vehicle's braking system health. By understanding the role of different lubricants and adhering to best practices during brake maintenance, you can significantly enhance safety, performance, and longevity of your braking components. Always consult with a qualified mechanic if you are unsure about any aspect of your vehicle's brake system.

If you ever have any questions, please feel free to contact our technical helpline on 01174 288100. Apec Braking is proud to provide you with technical information to support the quality of its products and to uphold its “Full Spec. Full Stop.” promise to customers.

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