The short answer is that the range of applications for copper grease is diminishing, which doesn’t render it obsolete but means that it is losing its relevance in the workshop.
Brake component lubricants are an inexpensive consumable used when replacing brake parts. A good brake grease is integral to correct brake system operation and can make a significant contribution to safety. More often than not, though, the lubricant doesn’t get a second thought because its use is so ubiquitous. Mechanics need to understand why copper grease has fallen out of favour when it comes to modern braking systems. We will demonstrate why the use of conventional copper‑based greases can actually have a negative effect on the operation and performance of modern braking systems.
Garage professionals will agree that performing repairs and carrying out component replacement on the braking system is of critical importance to vehicle safety and why brake service must not be rushed.
So, after taking all that time and doing a thorough job, what could be worse than a customer returning with a complaint, saying that the freshly serviced brakes are squealing or they are experiencing judder through the brake pedal? Despite doing a meticulous job, i.e. preparing all of the mating surfaces and components thoroughly etc, the brakes do not perform as intended. But, if quality components have been used and all service instructions followed, what has caused the problem?
Well, the answer could be something as seemingly benign as the choice of grease applied to the components or even the condition of the grease. An open tin of copper grease lying around on the bench, ready for the next brake pad change is a common enough sight in many workshops, but it is a potential problem because the grease is exposed to the elements. If grease gets contaminated with airborne dirt and moisture, the lubricant will become ineffective. Inclusions trapped in the grease possibly even preventing proper seating of the brake components.
The main reason for copper grease falling out of favour, however, is because it can affect the vehicle’s ABS, ESP and EPB systems. Braking systems or driver assistance systems are highly sophisticated these days and with every year that passes, more electronics are being used in vehicle braking systems. Electronic braking systems utilise extremely low voltage signals generated in the sensors. The low-voltage signals are easily disrupted and this is why using copper grease is a problem. Copper is conductive and its presence in and around the braking system can interfere with the Hall-effect sensors used in the system electronics.
If a wheel sensor signal is disrupted, the control unit interprets that as a failure and will switch on dashboard warning lights, possibly even causing a wheel to lock up under braking.
The simplest way to avoid problems like this is to make sure that you’re using the right grease for the right application, which, in the case of vehicles with ABS, ESP and EPB systems, is a copper-free product.
Copper-based products generally cannot withstand high temperatures. The lack of high-temperature stability can prevent the pads from moving freely due to drag and can also cause premature or uneven wear. Another disadvantage is that copper is known to promote galvanic corrosion. Galvanic corrosion can cause components to weld together because copper-based lubricants can accelerate the corrosion process. The environmental concerns are also a problem because copper grease does not break down efficiently, causing contamination of the soil and plant life, further adding to the list of negative traits.
The combined disadvantages associated with using copper-based greases on braking systems, probably outweigh any advantages. For the mechanic, the easiest way to go is to switch over to a copper-free alternative for all brake work.
The advantages of using a ceramic-based grease, on the other hand, are numerous. An important advantage is that ceramic-based greases can withstand the high temperatures at work in the brakes. The high-temperature stability means that the pads can move freely, eliminating factors such as drag and minimising uneven wear.
Possibly the main benefit is that ceramic-based greases can be applied wherever sensitive electronic components are utilised because it does not contain metal particles and is therefore non-conductive. Ceramic-based greases are highly versatile because you can also use them to coat the threads of spark plugs, glow plugs or for other high-temperature applications.
Copper grease, the trusty old partner to the experienced mechanic can cause problems if used on the current crop of braking and driver assistance systems. Copper grease used to be the go-to product, but many are turning their back on it now because times and technologies have changed.
The technological advances of the last few decades mean that copper-based greases are no longer the universal, one-product-fits-all choice. Today, it’s easier for busy garage professionals who cannot afford the inconvenience and the reputational damage of customers returning vehicles with complaints to simply use a product that will work first time, every time.