Masking Bolt Holes: Painting Calipers The Right Way

Painting brake calipers can be a tricky process, and one that requires careful preparation to ensure the paint doesn't end up on the bolts or get drawn into the threads. There are a variety of methods and materials that can be used to mask off bolt holes when painting calipers, including rolled-up paper towels, Blu Tack, masking tape, and wine corks. However, some of these options may be more effective than others, and it's important to consider the size of the holes and the type of paint being used when choosing a masking material. For example, silicone plugs are recommended for high-temperature processes like powder coating, while EPDM plugs are better suited for lower-temperature processes like plating and anodizing. Properly cleaning the calipers before painting is also crucial to ensure that the paint sticks and the job is done well.

Using wooden dowels or plugs

When it comes to masking off bolt holes for painting calipers, one effective method is to use wooden dowels or plugs. This technique is particularly useful when you want to prevent paint from getting into the threads of the bolt holes.

To employ this method, it is recommended to have a variety of wooden dowels and plugs in different sizes. For smaller bolt holes, wooden dowels can be inserted tightly into the holes, ensuring a snug fit. For larger holes, wooden plugs are more suitable. These plugs can be tapered, allowing for a secure fit and easy removal. When removing the tapered plugs, twisting them a quarter turn before pulling them out will help break the paint seal without peeling.

Having a range of sizes for your wooden dowels and plugs is essential to accommodate different bolt hole diameters. It is also beneficial to have threaded wooden dowels, as the threads will help grip the holes and provide better protection from paint. If you cannot find pre-threaded wooden dowels, you can create your own by adding threads to the dowels yourself. The threads don't need to be perfect; they just need enough grip to hold onto the bolt holes.

Applying grease or Vaseline

When painting calipers, it is important to mask off bolt holes to prevent paint from getting into the threads. While some amount of paint in the threads is inevitable, it is important to minimise this as much as possible. One way to do this is by applying grease or Vaseline to the threads.

Grease or Vaseline can be applied to the threads of the bolt holes to prevent paint buildup. This method is simple and effective, and it can help to lubricate the threads, making it easier to insert the bolts back into the caliper. The grease or Vaseline will create a barrier between the paint and the threads, preventing the paint from adhering to the bolts. This method is also useful if you only need to insert the bolt once, as the paint will act as a form of Loctite and stop the bolt from shaking loose.

To apply the grease or Vaseline, use a small paintbrush or earbud to coat the threads of the bolt holes. You can also use your finger to apply the grease, but be sure to wear gloves to avoid getting it on your skin. It is important to use a high-temperature grease or Vaseline that can withstand the heat generated by the brakes. Avoid using petroleum-based or multipurpose greases, as they may not be able to withstand the heat and could potentially damage the rubber components.

Silicone grease is a popular choice for brake caliper pins as it provides excellent high-temperature resistance and won't react with rubber. Synthetic greases, such as polyurea-based, are also a good option as they are durable and can withstand a variety of conditions. Mineral-based grease can also be used, but it is not always recommended. Lithium or lithium complex grease can be a good choice if it is high-temperature grade.

In addition to using grease or Vaseline, there are other methods to mask off bolt holes for painting calipers. Some people use wooden dowels, wooden plugs, or tapered wooden plugs that can be twisted and then pulled out to break the paint without peeling it off. Others use disposable foam earplugs, cork or rubber stoppers, or aluminium foil to cover the bolt holes. It is important to note that some of these methods may be more effective than others, and it may take some trial and error to find the best method for your specific application.

Using cork or rubber stoppers

When painting calipers, cork or rubber stoppers can be used to mask off bolt holes. These stoppers are designed to fit multiple hole diameters and create a tight seal to prevent paint from seeping through. They are easy to install and remove, and they offer excellent sealing ability.

To use cork or rubber stoppers effectively, follow these steps:

• First, ensure you have the correct size of cork or rubber stopper for your bolt holes. It's important to measure the internal diameter of the hole accurately using a digital caliper.
• Select a cork or rubber stopper that is slightly larger than the measured diameter. This will ensure a snug fit and create a tight seal.
• Insert the cork or rubber stopper into the bolt hole. You may need to twist it slightly to ensure it fits securely.
• After painting, remove the stopper by twisting it a quarter turn and then pulling it out gently. This will help break the paint without peeling it off the caliper.

It is important to note that cork or rubber stoppers may not be suitable for all types of painting processes, especially those involving high temperatures. In such cases, silicone plugs or EPDM plugs may be more appropriate, as they are designed for higher temperature processes like powder coating and e-coating.

Filling holes with Blu Tack

However, if you are in a pinch and have no other options, Blu Tack can be used as a temporary sealant or patching material to fill holes. It is composed of synthetic rubber, which allows it to stick to various surfaces without causing damage or leaving residue behind. Blu Tack is also non-toxic and easy to use.

To use Blu Tack to mask off bolt holes for painting calipers, start by rolling a small piece of Blu Tack into a ball. Gently push the ball of Blu Tack into the bolt hole, ensuring that it is securely in place. You can then paint the caliper as needed.

Once the paint has dried, use a sharp tool to carefully remove the Blu Tack from the bolt hole. It may take some effort to remove all the Blu Tack from the threads, so be patient and careful to avoid damaging the paint.

While Blu Tack can be used as a temporary solution, it is not ideal for filling holes during the painting process. For a more permanent solution, consider using wooden dowels, wooden plugs, or bolt hole masking plugs, which are specifically designed for masking bolt holes during painting.

Removing the caliper from the wheel assembly

To remove the caliper from the wheel assembly, you must first remove the wheel in front of the caliper. Use a tire iron or ratchet to loosen the lug nuts holding the wheel in place. Once the lug nuts have been removed, carefully pull the tire off the bolts holding it in place, exposing the brake assembly.

Next, locate the two bolts on the back of the caliper bracket, which is the large metal piece that clamps around the brake rotor, and use a ratchet to loosen and remove them by rotating them counterclockwise. If you can't get enough leverage to loosen the bolts, try attaching the socket to a longer breaker bar for more power. Once the bolts have been removed, carefully lift the caliper bracket off the brake rotor.

At this point, you can begin prying the caliper off with a screwdriver. Pull the brake pads from the caliper bracket, then remove the bracket itself. Finally, disconnect the caliper from the brake hose by turning the banjo bolt. With the old caliper removed, you can now prepare to install the new one.

Before installing a new caliper, it is important to clean the brake assembly with brake cleaner to remove any dust or debris. Position the new caliper over the brake disc, ensuring it is correctly aligned. Attach the new caliper to the brake assembly by securing it with mounting bolts and tightening them to the manufacturer's recommended torque using a torque wrench. This ensures the caliper is securely mounted and functions properly. Reconnect the brake hose to the new caliper, ensuring it is securely fastened.

Now, you can slide the brake pads back onto the caliper bracket and attach the new caliper to the bracket using bolts and a ratchet. Finally, lower the vehicle from the jack stands and check that the wheel nuts are tightened properly. It is crucial to test the brakes before driving to ensure everything is functioning correctly.

Frequently asked questions