One thing that makes the lubrication requirements for brake components different from that of steering and chassis components is heat. Brakes run hot. The front brakes on many front-wheel-drive cars and minivans, as well as trucks and SUVs, can easily reach several hundred degrees with normal braking, and get much, much hotter under certain circumstances. Riding the brakes in heavy stop-and-go traffic, mountain driving, aggressive driving, towing a trailer, or hauling a heavier-than-normal load can all increase the load on the brakes and the operating temperature of critical brake components.
At elevated temperatures, most ordinary chassis grease can't take the heat and will either melt or burn off, leaving surfaces unprotected and unlubricated. Worse yet, the grease may contaminate the brake linings if it melts and runs off the calipers or drum hardware. That's why high-temperature brake lubricant with a high solids content generally works best for brake system applications.
Another reason for not using ordinary chassis grease or multi-purpose grease on brake components is because these products are usually petroleum-based. As every technician should know, many petroleum-based products are not compatible with the seal materials that are commonly used inside brake systems. For this reason, petroleum-based grease or oil should never come into contact with the rubber seals, pistons or other internal parts in a master cylinder, brake caliper or wheel cylinder. If it does, the entire brake system should be considered contaminated. This will require draining and flushing the entire system, and replacing all the major hydraulic components! Why? Because petroleum-based products can cause incompatible seal materials to swell, rupture and leak, which could lead to fluid loss and brake failure.
Brake lubricants, by comparison, are specially formulated products that are designed exclusively for brake applications and nothing else. The chemicals in these products are compatible with all commonly used seal materials, and will not harm these parts.
TYPES OF BRAKE LUBRICANT|
WARNING: DO NOT USE OIL, GREASE, ANTI-SEIZE OR LUBRICANTS OF ANY KIND WHEN TIGHTENING LUG NUTS! Proper torque on lug nuts is very important for three reasons. One is to keep the lug nuts from loosening up and the wheel coming loose, another is to prevent distortion of the brake rotor behind the wheel, and a third is to prevent broken studs. A torque wrench should be used for final tightening of the lug nuts, and the nuts should always be torqued to the recommended specifications. CAUTION: Torque specifications for lug nuts are always for CLEANand DRY studs and lug nuts. That means no oil, no grease, no anti-seize and no lubricants of any kind. Any of these products will reduce the friction between the threads. This may seem like a good thing to prevent rust and frozen lug nuts, but the reduction in friction means a much higher percentage of the applied torque (up to 25% or more) will go toward loading the lug nuts. The end result may be brake rotor distortion or broken studs! Wheel studs should be cleaned with a wire brush to remove rust and dirt BEFORE the wheels are mounted. If the lug nuts are heavily rusted or have damaged threads and won't turn easily on the studs, replace the lug nuts. The same goes for any wheel studs with damaged or badly corroded threads. And remember to mount the wheels DRY with nothing on the threads. |
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