A big part of owning a motorcycle is always making sure it's well maintained and road-worthy. For the rider, this means checking up on little things like the battery, bulbs, lubricants, and the tires. Other matters are usually best left to service centers or shops, as part of your preventive maintenance service. Yet with the community quarantine currently in place, you might not have that option right now.
For those of you with the right tools and parts, many of these more complicated maintenance procedures — like changing brake pads, the chain or drive belt; batteries, and spark plugs — can be a do-it-yourself (DIY) affair.
Like most dirt riders, I also do most of the maintenance work for my motorcycle mystelf. As some of you may know, riding off-road does some serious wear and tear on the bike. As such, over the years, I've invested in tools so that I don't need to pay someone to work on my bike as frequently. Not only will it save me time and money, but it is also reassuring to know that the job is done the way I want it to be.
We also encourage you to read your motorcycle's owner's manual before doing any maintenance work on your bike, paying special attention to the maintenance intervals and how to's.
Though typically best left to shops or mechanics, brake pads (for disc brakes) are one of the parts you can actually install on your own. Replacing your bike's brake pads is actually pretty easy. In most cases, it only requires the basic tools found in the factory toolkit of your motorcycle. Before starting, make sure you have a new set of brake pads on hand.
We'll also cover cleaning your brake system. It's fairly easy to do, but feel free to skip that step if you don't ride off-road or you find it too complicated.
Like what we always say: before starting any bike work, clean your motorcycle first. We share tips on how to do it in this story: Motorcycle TLC that will keep you busy during lockdown.
Parts of a brake
Whether with an Anti-lock Braking System (ABS) or without, the basic components of disc brakes are generally the same. The system has three parts: the caliper, disc and the master cylinder.
Caliper
The brake caliper is the part that holds the brake pads and squeezes the disc when the rider applies pressure on the brake lever. Motorcycles are usually fitted with floating calipers with just one piston. When the brake lever is squeezed, the piston pushes the pad towards the disc. Once this side makes contact with the disc, the other side (mounted on sliding pins) is also pulled toward the disc to bite the disc, creates friction, and slow down the wheel's movement until the lever is released.
Disc
This is the shiny, circular metal surface connected to your motorcycle's wheel. The brake pads squeeze this surface to slow down the bike.
Master cylinder
This is a device that converts the force you apply on the brake lever into hydraulic pressure. Brake fluid, stored in the reservoir, travels through brake lines towards the piston. Because brake fluid cannot be compressed, it pushes the piston, which in turn, causes the brake pads to bite the disc and slow down your motorcycle.
Now that you're familiar with the brake components and their function, let's start with the replacement of the brake pads. I'm working on a Honda dirt bike, but nearly all motorcycle disc brake systems work the same way.
1. PREPARATION
Keep the bike stable
You'll be unscrewing some tight and tough parts so be sure your motorcycle is stable and won't move. Before starting your work, place the bike on a center stand or any sturdy motorcycle platform. This is to ensure that the bike is standing straight. It's easier to work on the bike this way.
Gather your tools. You'll be needing wrenches. We recommend keeping a penetrating oil (like WD-40 or Mechanix 5) nearby. Pro tip: You'll be working with a lot of bolts and screws. They may be screwed on tightly and difficult to remove. To avoid rounding these bolts, we highly recommend using a box, socket, or ratchet wrench instead of an open wrench. These require much less effort.
If you intend to do the cleaning part, you'll need an old toothbrush, steel wool, a basin to wash the parts in, and laundry detergent (preferably liquid). Finally, you'll need an old rago (trapo) to dry the parts with.
Also have gloves and protective eyewear handy as you'll also be dealing with dust and brake fluid which may irritate the eyes and skin.
Keep a tray nearby. Put the screws and parts you remove here. Having a tray makes it easy to organize the parts and remember screw positions, making it easier to put them all back together later on.
2. REMOVAL
Remove the wheel (optional)
Though this step is optional and could mean extra labor, removing the wheel gives you a lot of room to work with. This will also give you a better angle when inspecting your brake caliper, disc, and brake pads for signs of damage before removing it. This extra step is also a great opportunity to check your wheel bearings, which, under normal riding conditions, should last 30,000 to 40,000 kilometers from my experience on small bikes. On dirt bikes, they usually need replacement sooner since, off-road riding exposes it to mud, sand, and even water. Regular exposure to these elements can wear it down faster.
Spray penetrating oil
Since your bike's brake calipers are exposed to a lot of mud and dirt brought about by daily riding, spray penetrating oil on the screws. Penetrating oil also acts as a cleanser, removing dirt off them. This also lubricates them, making removal of these easier.
Use the right size of Allen wrench
Generally, the pin screw that holds the brake pads in place requires a hex key, Allen wrench or Torx for big bikes. Always make sure to use the right kind and size or you risk damaging and rounding the head of the screw, making it difficult to grip after. If you're not sure of the size, test fit and turn it lightly to make sure it grips the screw head. If it doesn't even cover the screw, it's too small. If it slides a lot, it's too big.
Pro tip: Before unscrewing, pay close attention to where and how the retainer and spring pads are placed. These thin sheets of metal keep the brake pads in place. These are important to keep track of because, after removing the pin, the pads will fall off. These parts may fall off too.
Worn brake pads like these, have very little material left to grip the disc.
By this time, you'll have a good look at your brake pads. Worn brake pads (like in the picture) have very little material left to grip the disc. It's important to replace these before they completely wear out to prevent metal-to-metal contact between it and the disc. The resulting damage can cost you more on repairs, possibly need a rotor replacement, as well as being dangerous for riding since the brakes are compromised.
3. CLEANING
Pump the brake to push out the piston
As you have noticed by now, your bike's brake caliper may require some serious cleaning, including the piston. Dirt and grime can accumulate even on the piston after years of riding. Putting in new, thicker brake pads with a dirty piston could damage the oil seal of the caliper. Cleaning it will ensure smoother movement of the piston.
To simplify the piston's removal, pump the brake pedal (for the rear brake) or lever (for the front brake) to push out the piston. If you're doing it right, it should look like the photo above.
Remove the caliper from the sub-assembly
This step is pretty straightforward. Remove all the bolts that attach the caliper to the sub-assembly, including the fluid bolt connecting the caliper to the master cylinder. Keep track of where each part goes for reassembly later.
Use protective goggles and gloves, if you have. Be extra careful when handling these parts. They may be coated in brake fluid. This is a toxic substance and may irritate your skin. Don't rub your eyes when handling these parts.
Clean the caliper
The good thing about cleaning the brake caliper is that it doesn't require a special cleaner or solution. All you need is an old toothbrush, steel wool, warm water and laundry detergent (preferably the liquid kind). For the caliper, start brushing from the inside, working your way out. It's done in this manner so that dirt from the outside won't get inside the caliper.
Using the steel wool, generously scrub the piston until all the dirt and grime is removed. In some cases, grime may have settled for too long and may have already corroded the piston. If this is the case, consider replacing your brake caliper piston (through a repair kit) as it may compromise the brake system's ability to do its job: stopping your motorcycle.
With small items like O-rings, bolts, and the retainer springs, take extra care as these can bend and deform easily.
Rinse the parts with clean water. Dry all of the parts by wiping them on an old rag (trapo). Do not begin reassembly if they are wet or damp. If you have an air compressor and blower, you can use it to blow off excess water from the caliper.
4. REASSEMBLY
Reassemble the caliper
Still remember how to put it all back together? Returning the caliper to the caliper sub-assembly will be the same process in reverse order. Gather all the parts and begin to reassemble the caliper. Start with the caliper.
Pro tip: Before re-installing the caliper piston, use your finger to put a generous amount of brake fluid onto the oil seals (like in the photo above). This not only ensures a perfect fit, but the brake fluid will also act as a lubricant, making it easier to re-install the piston. Once done, push the piston all the way in, until it flattens out and is level with the caliper's inner surface.
Before attaching the other half of the caliper (the side without a piston), put a little grease on the sliding pins like in the photo above. The grease keeps water away and also ensures smooth movement of the floating brake caliper.
5. INSTALLATION
Install new brake pads
Make sure that the retainer and spring pads are placed in the correct manner. Re-install the new pads by putting the side closest to the piston first. Then insert the other pad.
Screw in the pin screw to lock the new brake pads in place. Be extra careful not to over-tighten the screws. The rule of thumb is, just use one hand to tighten them. Use only the force of your wrist, about the same force you would use to tighten the cap of a bottle of soda. Pro tip: Like what was suggested above, put a little grease on the pin screw before screwing it back in.
Job done!
There you have it! You have now done a DIY brake pad replacement and caliper cleaning. It might not be as easy your first time, but doing it again will help you familiarize yourself with the process. Investing in some tools for this can also make the job easier. And if you're up for doing this kind of thing, it can save you a lot in terms of bike maintenance costs. These skills will also come in handy in more unpredictable situations, like during an out-of-town ride with your friends.
If you plan on doing more DIY maintenance, we recommend stocking up on consumable parts like brake pads even if you don't need them yet. They'll come in handy if the parts break or wear down sooner than you expect. They're also perfect for the current situation, with much of the country on lockdown and there are no motorcycle shops open. With all the idle time, you could do some bike maintenance.
Please stay tuned for our next feature related to this, the second part of a motorcycle's braking system maintenance: brake bleeding.
