Stop motion: How to service your brake calipers

You can service your brake calipers at home
You can service your brake calipers at home
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Cleaning and servicing your brake calipers is a crucial job if you’ve ridden through winter or had the bike laid up for a while, but it only takes an afternoon. So what are you waiting for? 

But where to start? Well, a brake caliper is the bit of equipment on your bike that contains the brake pads along with the hydraulic mechanism that presses the pads against the disc. That means there are several parts in there that move regularly with a reasonable amount of force. As a result, engineering tolerances are high and it’s important you do this job in a structured fashion.

You don’t need to be an engineer in order to service your brake calipers, though. It’s easily achieved by an amateur mechanic at home. So if you’re curious about how to unsieze a brake caliper, or how to open a brake caliper piston, this article can help. 

What you need to service your brake calipers:

The equipment you need to service your brake calipers

Step-by-step guide to brake caliper servicing

1. Tough get going

Prevent binding by giving your brakes a good service

Dirty pad retaining pins and mucky pistons can cause binding as well as a harsh pull at the lever, so cleaning both keeps things slick. When doing this task, it’s best to work on one caliper at a time, as pushing out the pistons in both calipers could run the fluid reservoir dry. Remove the retaining pin before removing the caliper as they can seize in place, making removal difficult.

2. Remove the pads

Removing brake pads

With the pin out, remove the pads and inspect them for condition. Take a note of which side of the caliper each pad comes from so they can be put back in the same position if they have plenty of life left in them. If they are worn then this is the time to source replacements. Check that they are the correct spec by laying them side by side with the originals to make sure they are identical.

3. Get ready to scrub

Fill a standard V1.0 bucket

Fill a bucket with warm water and add in a bit of bike cleaner. Moisten the caliper with water and then spray on some brake cleaner and allow it to dwell for a minute or so. The cleaner will penetrate and loosen dirt and contamination. Be accurate when spraying cleaner on the brake caliper, as you don’t want to be overspraying on to the brake discs and fork legs.

4. Give it some agitation

Agitate the grime

Using a suitable nylon brush, agitate the cleaner and pay attention to the areas that are within the caliper and between the pistons. It’s important to clean the pistons, so pump them out with the lever (not too far!) and scrub the sides. Also scrub the pad retaining pins and anti-rattle springs.

5. Rinse thoroughly

Rinse away dirt

Use a hose to gently rinse away the dirt, or use a sponge with clean water to do the same thing. Rinse between the pistons and make sure that the inside of the pistons aren’t harbouring a mini reservoir of scuzz. It’s important that all of the cleaner is rinsed  off otherwise it can leave a white residue when dry.

6. Give it some air

An air compressor is an extremely useful bit of kit

If you have an airline, then use it to blow away most of the water. Use a drying towel that will absorb all remaining moisture and dry inside the caliper pistons. With the caliper dry, apply some red rubber grease to the pistons, then push them in and out a few times. You’re looking for minimal resistance, so that when you release the lever the pistons relax.

7. Refitting the pads

Refitting the pads into your brake calipers

When fitting pads, you’ll need to gently push the pistons back. There are ‘winding back’ tools you can get for this specific job but if you are careful you can use a large flat tool to ease them back slowly. Try to avoid big screwdrivers, as you can damage the pad. A whole book could be written on copper grease but it’s rarely required on modern pads.

8. Refit and torque it up

Torque up your bolts

With the pads fitted check that any retaining pins, clips or shims are installed as per the workshop manual. Refit the caliper and tighten up with a torque wrench. Check the tightness on any pad-retaining fasteners. Pump the front brake lever – initially it will feel soft but after a few pumps it should start to feel normal again. Check the brake fluid level in the reservoir is correct, top up if necessary with fresh fluid.

9. Give it a final clean

One last clean

Using clean workshop paper towel, clean the brake disc with a dedicated brake cleaner. Most discs have two parts – the carrier in the middle and the brake disc surface itself. Clean the carrier first using brake cleaner and wipe it off with clean workshop paper  towel. Clean the outer disc last using fresh paper towel and brake cleaner. Use a rotating motion with the towel until the disc is wiped clean.

And that’s it! Job done. You’ve now successfully serviced your stoppers. 


 

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Bruce Dunn

By Bruce Dunn

Datalogger, professionally testing bikes for over 25 years.