temperatures, most ordinary chassis grease can't take the heat and will either
melt or burn off, leaving surfaces unprotected and un lubricated. 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.
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.
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
TYPES OF BRAKE
Some brake lubricants are designed for lubricating hardware and mechanical
components, and typically contain a high percentage of solids ("dry film
lubricants"), and some are designed for lubricating seals, boots and other
internal parts when assembling calipers, wheel cylinders and master cylinders.
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 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� 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.
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� F to 400� 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
suitable 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.
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 F, and can be used for both assembly and external
is a low-temperature grease that can be used to lubricate drum brake hardware
and backing plates, but lacks the heat-resistance for front disc brake
applications. So it's not the best choice for general brake work.
what type of brake lubricant you choose, always follow the supplier's
recommendations as to how to use their product.
should be used at every point in the brake system where parts slide or move.
With disc brakes, lubrication points include the caliper slides, pins and
bushings, the contact points where the pads slide within the caliper housing,
self-adjuster mechanisms on rear disc brakes with locking calipers, and the
parking brake cables and linkage.
can also be used to dampen vibrations between disc brake pads and caliper
pistons. But it should not be applied between the pads and any noise suppression
shims that may be used. Use it on the back of a bare pad or between the pad shim
and caliper. And use it sparingly - don't glob it on.
The primary lubrication points in rear drum brakes include the raised pads on
the backing plates that support the shoes, the star adjuster mechanisms, hinge
points for self-adjusters or the parking brake linkage, and the parking brake
One place you
never, ever want to get any grease is the friction surface of a brake lining -
which is another reason for not using low-temperature or petroleum-based
lubricants, which can melt, run off and foul the linings. Grease-contaminated
shoes or pads will be grabby and usually cause a brake pull to one side. The
only cure is to replace the fouled linings with new ones. Cleaning is out of the
question because solvents and cleaners can adversely affect the linings, too.
hydraulic components such as the piston seals inside calipers and wheel
cylinders, you can use a silicone-based brake lubricant or ordinary brake fluid.
This type of lubricant will help assure smooth movement of the seals in their
bores, and will help prevent these parts from sticking or corroding.