SEVERAL BASIC TYPES
There are several basic types of brake lubricants: those that are designed for lubricating hardware and mechanical components and typically contain a high percentage of solids (“dry film lubricants”), and those that are designed for lubricating seals, boots and other internal parts when assembling calipers, wheel cylinders and master cylinders.
Brake lubricant for hardware is a special high temperature grease designed to provide long-lasting protection. The lubricant may be a synthetic or silicone-based product. Synthetic-based, “boundary”-type lubricants that come in a tube, paste or stick form have a high solids content and typically contain a variety of friction-reducing ingredients such as molybdenum disulfide (“moly” or MOS2) and graphite.
Moly and graphite are both dry-film lubricants that can handle high temperatures and pressures. Some of these products are rated to withstand intermittent temperatures as high as 2,400 degrees F!
Moly and graphite have excellent staying power and won’t evaporate or burn off over time, and they won’t attract or hold dirt like ordinary “wet” greases can. This type of product is ideal for high temperature applications where long-lasting metal-to-metal lubrication is essential for good brake performance.
Silicone-based brake grease is designed for caliper and wheel cylinder assembly work because silicone is an excellent lubricant for rubber and plastic. It is compatible with all rubber compounds including nitrile, teflon, nylon and other synthetic rubbers.
Silcone’s normal working range is -40 degrees F to 400 degrees F. But it does not have the high temperature staying power of a high solids synthetic lubricant, and it is a “wet” lubricant that can attract and hold dirt, making it less suited for lubricating external metal-to-metal contact points such as caliper mounts and shoe pads. This type of product is best suited for assembling calipers, wheel cylinders and master cylinders.
Another synthetic-based brake lubricant uses polyalphaolefin (PAO) as its main ingredient. PAO-based brake lubricants are also excellent for assembly work and lubricating seals and boots. PAO offers superior rust protection, making it well-suited for brake systems operated in wet environments.
PAO brake lubricant may also include various amounts of moly, graphite and teflon to enhance its lubricating properties. This type of product can withstand intermittent temperatures of up to 600 degrees F, and can be used for both assembly and external lubrication.