How to clean rust inside a brake caliper

What happens if you remove the piston from a brake caliper and find rust inside the body? How do you repair it? How do you remove the rust?

Rust usually appears in our vehicle due to the excess humidity to which our car is exposed. In general, this type of problem usually occurs in the brake discs and calipers of our vehicle either because it has not been used for a long period of time, or due to rain, snow, or other meteorological phenomena that can also cause rust to accumulate on the outside of the calipers. However, when it appears on the inside of the brake caliper it means that moisture has been entering the piston cavity, which should not happen.

From Frenkit, we bring you this post where we show you several very useful methods that will help you to properly clean the rust of the brake calipers of your vehicle. Read on!

4 methods to clean the inside of a brake caliper

If you want to replace or change the brake caliper components, there is a possibility that the caliper itself may be stuck or damaged internally. This can cause the new components we have replaced to malfunction or damage them.

Therefore, due to Frenkit's experience in spare parts and repair kits for vehicles, we show you four procedures to correctly clean the inside of a brake caliper; in this way, cleaning will not affect the inside diameter of the caliper. These methods help us to remove rust from brake calipers:

Clean with water-based sandpaper

The first and most important step is to clean the surface of the brake caliper with water-based sandpaper with a grit size between 800 and 1,000 grit. This type of sandpaper is suitable for brake cleaner or lubricant, and the correct way to use it is to apply a coat and, using concentric movements with respect to the hole, sand the entire rusty surface.

Cleans rust with compact rotary tool

The second technique is to use a compact rotary tool with a brush head made of brass or another metal that is softer than steel. Thanks to this brush head, the surface of the brake caliper is not scratched, as brass is a softer material. With this second method we save time and quality, but we have to be more careful than with sandpaper, as we remove more material in less time. Also, with this procedure we will again follow the concentric circular movements.

Clean the brake caliper with rust remover fluid

This process consists of cleaning the brake caliper with a cleaning fluid that removes rust. It is a very easy process to carry out, as it is only necessary to follow the specifications of the product. Generally, the brake caliper is left in the fluid and, after waiting the time specified by the product itself, the surface is cleaned with a cloth and alcohol.

Cleans with a shot blasting machine or sandblasting cabinet

This last technique is the least conventional. On the one hand, we can use a shot blasting machine, which propels small spheres of different materials towards the surface of what we want to clean, eliminating dirt or any contaminating material on the part. On the other hand, there is the sandblasting cabin, with a process similar to that of the shot blasting machine. It is smaller which performs a thorough and precise cleaning of the caliper, with which we manage to remove all surface corrosion, giving the brake caliper a perfect finish. Sand or fine grit hardly reduces the thickness of the surface, only the rust. It must be taken into account that the blown material should not be harder than the steel of the brake caliper. Therefore, from Frenkit, we recommend you to use glass beads or steel beads, with a hardness of less than 50 HRC.

Now that you know these four methods to properly clean rust from a brake caliper, we advise you to keep in mind that, regardless of the process you work with, it is also advisable to apply a finish with a polishing brush and polishing compound or polishing putty.

If you found this post on how to clean rusty brake calipers useful, at Frenkit, a company specialised in manufacturing and distributing brake components for passenger cars and light vehicles, we offer you a wide range of products and kits to repair and care for your car.

If you need more information about our repair kits, do not hesitate to contact us, we will be delighted to help you!