How to properly maintain a brake caliper. What and how and when to lubricate

It’s time to stop believing in the fairy tales of auto chemical goods and greases sellers that it is enough to buy one tube of universal grease to service brake calipers. Especially today, when in any self-respecting store you can buy separate grease for brake pads, grease for caliper guides and grease for pistons of the working cylinder. Our job is to understand how to grease the brake caliper and each of its mechanisms separately.

Читати Українською

Why and when to grease the brake caliper

“Each brake caliper mechanism” sounds a bit odd to many. In fact, the caliper is a technically complex unit in which every detail requires special attention. If we’re talking about the classic floating caliper disc brake caliper, here’s what we get.

Brake pads, caliper noise

Creaking, screeching brake pads are familiar, probably, to everyone. 90% of noise from brake pads does not come from the plane of direct contact with the brake disc. And from the anti-creak mechanism (!), the backside of the pad, as well as the noise depends on the general condition of the caliper.

And, of course, on the quality and composition of the friction lining. We talked about this in more detail here. In addition, the critical wear of the brake pads does not mean at all that the lining has been worn down to zero. In most cases, 3-4mm lining thickness (and even more uneven) screams that the caliper needs service.

Anti-squeak plates

An excellent invention of Bosch engineers, but it requires care. Using the wrong lubricants on the anti-squeak mechanism, only exacerbate the problem. With every brake pad change, we spend a few minutes of our precious attention and the pads no longer squeak. But it is important to know how to lubricate them.

Caliper pins

This wording applies exclusively to classic-type brake calipers used in the vast majority of budget (and not so) cars. The simplest spare part controls the behavior of the entire brake mechanism. She doesn’t care about all the electronics. If the caliper pins are in poor condition, expect problems.

It is important to keep in mind that caliper pins are not such an expensive part to restore (There are examples when they are simply riveted with a hammer). It is safer to pay exorbitant prices, but be sure that the brakes will be in order.

Pins dust cover

The condition of the caliper pins directly depends on the viability of the rubber boot. It is he who protects the pins from water, sand, dirt. Any crack in the anther is a blow to the health of the caliper pins.

A little advice. If we buy a repair kit for a caliper, it is extremely important to look at the quality of the anthers. Even eminent brands sometimes slip outright rubbish into repair kits. Good anthers will be elastic, look neat, as in the photo below.

The piston of the wheel brake cylinder

From time to time you watch popular videos on video hosting sites, and your hair stands on end. Masters, as it were, with experience, put almost lithium greases or silicone grease into the pistons of brake cylinders.

The problem is this. Corrosion eats up the piston of the wheel cylinder for the reason that the driver did not replace the brake fluid in time. But he doesn’t know about it. He thinks that the piston is made of stainless steel and will endure everything in the world.

No. Brake pistons are made of hardened steel and chrome plated.

When the chrome wears off, lousy brake fluid (any brake fluid absorbs moisture at an alarming rate) gets to the piston body. And this is where special lubricants are needed. At least to keep the brakes from sticking pistons.

First conclusions

1. Lubrication in the caliper is important not so much for optimizing the operation of the mechanism but for prevention.
2. The brake caliper must be greased every time the brake pads are replaced. Most officials and private masters know about it. But they don’t.
3. Each part of the brake caliper needs its own grease. Universal does not exist with rare exceptions.
4. By neglecting brake caliper lubrication, we endanger both ourselves and our passengers.

Any little thing that concerns the brake mechanism is not a small thing.

Brake caliper grease requirements

Standard greases, graphite grease, any general-purpose grease are not suitable for use in brake calipers. The reason is simple. The dropping point of standard greases does not exceed 60-70 °C.

Calipers from time to time warm up to 500-600 °C, respectively, the usual lubricant will flow out of the assembly without a trace at the first heating.

In fairness, it must be said that such a high temperature occurs only in the friction zone of the friction lining of the brake pad on the brake disc. Thanks to the massive design of the caliper, heat is evenly distributed throughout the mechanism, and at the points farthest from the pads, the temperature reaches a maximum of 200-250 degrees.

If we do not want the brakes to fail at the most crucial moment, caliper greases must meet certain requirements:

1. The melting point of the grease must be above 500 °C.
2. Lubrication should not be aggressive towards rubber parts (guide boots, brake piston boot and cuffs).
3. The lubricant must not be dissolved by brake fluid and water, as well as road chemicals.
4. The composition must be compatible with all types of elastomers used in brake mechanisms (rubbers based on propylene, ethylene, ethylene-propylene copolymers).

Who produces greases for calipers, lubricant groups

In most cases, brands that make classic lubes do not make caliper lubes. To do this, you need to work with other materials, as well as have the appropriate equipment.

In order to sell their products, caliper grease companies sign contracts with either well-known brands of greases or brands that produce spare parts for brake systems. Sometimes they are taken under the wing of car manufacturers.

Here are some of the main brands that produce greases of interest to us:

1. HUSKEY Specialty Lubricants. Known under the brand name HUSK-ITT Corp, they produce a full range of caliper lubricants. May be marketed under the Huskey and Slipkote brands.
2. Kluber Lubricarion Munchen KG, also on sale there are all groups of greases for brake calipers.
3. Molykote brand produces caliper lubricants under the Dow Corning Corp brand.

Of course, there are many more for sale. However, brakes are too critical a mechanism to be greased with anything.

All greases for calipers are divided into three categories depending on the purpose of their application:

1. Greases that can withstand exposure to high temperatures, their main property is anti-seize. They are used to lubricate mating parts of brake pads and anti-creak plates. Most often they are labeled as Anti-Seize.
   This is the most widely used group of greases. This includes greases containing copper, graphite, aluminum inclusions, molybdenum disulfide, ceramics, magnesium silicate, and other non-metallic additives.
2. The edges of the pistons of the working brake cylinders, plastic bushings, parts in contact with elastomers (seals) belong to the second group of lubricants. They are labeled as Rubber Grease. The use of any silicone greases, in this case, is unacceptable.
3. The third group of lubricants is the most common. It includes universal greases for all moving elements of the caliper. Suitable for parts that come into contact with plastics and elastomers.

Caliper lubricant types

As you can see, there are not so many universal tools for servicing the caliper, and they cost 40 percent more than the rest. Now let’s go through the personalities and try to find the right lubricant for the right part.

Anti-seize lubricants in the caliper

There are many requirements for such materials. Firstly, the temperature of drop formation (the beginning of fluidity) should not be lower than +1500 °C, and secondly, the proportion of solid antifriction materials or metals should be at least 25-30%. Such greases are made mainly on a mineral basis, although there are exceptions.

Tellingly, such lubricants are used not only for processing the brake caliper, but for the mass of other structural elements of the car. However, this needs to be discussed separately.

General-purpose anti-seize greases are on sale:

• HUSKEY 2000 Lubricating Paste and Anti-Seize Compound for High Temperature;
• Loctite #8060/8150/8151;
• Wurth AL 1100.

Some prefer lubricants containing copper:

• HUSKEY 341 Copper Anti-Seize;
• LIQUI MOLY Kupfer-Paste;
• Loctite C5-A (#8007/8008/8065);
• Mannol Kupfer-Paste Super-Hafteffekt;
• Marly Cooper Compound;
• Molykote Cu-7439 Plus Paste;
• Motip Koperspray;
• Permatex Copper Anti-Seize Lubricant;
• Pingo Kupfer-Paste;
• Valvoline Cooper Spray.
• Wurth SU 800.

Or molybdenum disulfide compounds:

• HUSKEY Moly Paste — Assembly Lubricant & Anti-Seize Compound;
• Loctite #8012/8154/8155.

In some cases, it is necessary to use mild greases that do not contain metals:

• HUSKEY 400 Anti-Seize;
• TEXTAR Cera Tec;
• LIQUI MOLY Bremsen-Anti-Quietsch-Paste.

Greases for rubber and other elastomeric materials

These are the materials of the second group, which must be used to lubricate the edges of the pistons of brake cylinders, the ends of the anthers, cuffs during assembly, bushings, and seals. The two best lubricants in this category come from Germany:

1. Loctite Teroson Plastilube. Mineral-based paste with a mineral thickener (in our case it is bentonite clay). Works great at temperatures from -50 °C to + 190 °C.
2. ATE plastilube. A grease with very similar characteristics, a complete analog of Teroson Plastilube paste from the eminent manufacturer of brake system components Continental Teves AG & Co.

Of course, there are other pastes, but for these purposes, it is necessary to use formulations marked Rubber Grease.

Universal Caliper Lubricants

The third group of lubricants is represented by general-purpose compounds, both yours and ours. Accordingly, they perform their work mediocrely, but they are inexpensive and can be used in all budget cars without exception.

1. Molykote AS-880N Grease. 100% synthetic, silicone thickened. Contains solid synthetic additives, black paste. It melts at a temperature of +250 degrees, and the nominal operating temperature is from -40 to +210 degrees. Often sold in retail chains under the brand of a car with a specific catalog number.
2. Permatex Ultra Disc Brake Caliper Lube. Non-melting, fully synthetic green grease. Operating temperature range from -40 to +210 degrees.
3. SLIPKOTE 220-R Silicone Disc Brake Caliper Grease and Noise Suppressor. One of the most popular synthetic oil-based pastes with a synthetic thickener. A characteristic feature is that it does not melt at all, but has a temperature range in which 100% does not lose properties – from -45 to +300 degrees.
4. SLIPKOTE 927 Disc Brake Caliper Grease. Синтетическое масло плюс синтетический загуститель. Содержит частички дисульфида молибдена с включениями графита, цвет серый. Не плавится, оптимальный диапазон температур от -30 до +1200 градусов.

Let’s sum up the results. How to properly grease a caliper

We brought only a tiny part of the original greases. In the market, in most cases, pastes are sold in branded packages, for example, TOYOTA Disc Brake Shim Grease 08887-80409. 

The real name is sometimes only seen on the 20-40 kg pails supplied to wholesalers and dealers. Lubricants are often found in original packaging from manufacturers.

What should the average owner choose? Of course, lubricants of the third group. They are cheaper and can work with almost all brake caliper parts.

However, if you want the brake mechanism to work with 100% efficiency in order to prevent corrosion and cracking of anthers and cuffs, it is better to be selective with greases.