AP Racing Radi-CAL Competition Big Brake Kit, BMW E90/E92/E93 M3/1M Coupe

The conventional painted finish of aftermarket calipers often presents a noticeable weakness. Typically available in red, black, or gold, these painted finishes aim to enhance aesthetics and provide some protection against corrosion in harsh winter conditions. However, when subjected to track environments, painted calipers are prone to chipping, flaking, fading, color shift, and general degradation within a relatively short period of time. Even some OEM calipers can turn an unsightly shade of brown after just a single weekend. While some dedicated enthusiasts may view these signs of wear as a mark of distinction, the reality is that the appearance suffers. Additionally, the paint particles can end up in unwanted places, as we will explain shortly.

The primary cause of these issues is heat. Traditional paint and powder coat finishes are unable to withstand the extreme temperatures experienced on the track. Powder coat finishes, in particular, are known to shrink. As the caliper heats up, the powder coat layer expands and grows. However, during the cooling process, the powder coat does not necessarily shrink in proportion to the caliper body. Consequently, the finish becomes loose, ultimately cracking and deteriorating.

Paint finishes can also encounter similar problems depending on the application process. If you were to compare aftermarket calipers from the same manufacturer, you would likely observe slight variations in the painted finish. Some calipers may have a thicker coat, while others may have a thinner coat, resulting in slightly different shades of color. Painting is, to some extent, an art form that requires a tightly controlled environment. Any deviation from these controlled conditions can lead to variation. A thick coat may give the appearance of softness around the edges and is prone to cracking, similar to powder coat. Conversely, insufficient paint coverage can create an uneven look and offer inadequate protection for the underlying aluminum. Furthermore, both paint and powder coat finishes can undergo significant color shifts when exposed to heat. Red may transform into maroon or black, gold may turn brown, and black finishes may lose their visual appeal.

In contrast, the calipers used in the AP Racing Radi-CAL Competition Kits feature an Electroless Nickel Plated (ENP) finish, eliminating the issues associated with painted calipers. ENP offers exceptional hardness and resistance to wear and corrosion. It is widely employed in various applications, ranging from the manufacturing of hard disc drives to the construction of targeting pods for the F-15 Eagle fighter jet. ENP is particularly well-suited for calipers that require frequent bleeding, as it does not chip or flake like painted calipers when accidentally bumped with a wrench. Moreover, the thin and uniform application of ENP can accommodate the intricate curves and pockets of complex caliper designs, such as the AP Radi-CAL. The extremely low porosity of ENP makes it highly suitable for components exposed to harsh chemicals like brake fluid. If fluid, dirt, or debris come into contact with the calipers, ENP is remarkably easy to clean, quickly restoring its lustrous appearance. Finally, ENP provides a distinctive liquid metal-like finish, enhancing the visual appeal of your brake system. Its neutral yet eye-catching appearance blends seamlessly with any color scheme, capturing and reflecting light in a captivating manner.