Since the arrival of the Haynes manual, I’ve not thought it overly necessary to keep posting how-to’s, unless I were undertaking an undocumented procedure. Performing a partial strip down and service of the front brake calliper is one such procedure. I do this every 2’500 miles, as I ride during winter when the calliper and its components are extremely vulnerable to road salt. If left unchecked, the brake will bind, internal components will seize and sorting out that mess will be complicated and possibly expensive. A stitch in time saves nine and all that…
Warning: The brakes are a life-and-death part of your bike! Don’t tinker with them unless you have the technical competence to do so! If in doubt, seek professional help. Some of the chemicals used are quite nasty – protective gloves should be worn and the area should be well ventilated. As always, I take no responsibility whatsoever for anything terrible that may result by following what I’ve written. This article is to be treated as an account of my own personal experiences.
What this procedure involves is essentially removing the pads, detaching the calliper, partially disassembling it, cleaning everything up, paying particular attention to the more vulnerable parts, inspecting these parts for corrosion, wear and damage, applying the correct greases in the correct places and putting it all back together again. It takes about 1/2 an hour to do this.
Here are the tools I use:
- Torque wrench
- Breaker bar
- 8mm and 12mm sockets
- Toothbrush (not one you currently use on your teeth!)
- Red rubber grease
- Loctite 243 (blue).
- Copper grease
- Brake cleaner
- 240 grit wet and dry paper
- Newspaper and kitchen towels
To start, the brake pads are removed first. I first push the calliper inwards towards the disc with the palm of my hand so that the pads can be removed more easily.
Next, the pad retaining pin is removed with the 8mm socket:
Now the pads may fall out, or they may have to be pulled out. Here they are, nice and filthy. Now is the time to check how much friction material you have left. In my case, I have a good few thousand miles left out of these – might need to change them at the next service:
From the perspective of facing the the front of the motorcycle, the pad on the left faces the left side of the disc and the pad on the right (with the hook on its end) faces the right side of the disc. The friction material should be at least 2mm thick and evenly worn (not thicker at one end of each pad than the other and the same thickness on both pads. It should not be cracked or show any signs of damage (chunks missing etc). If in doubt, pads should replaced.
Put the pads somewhere safe – we don’t want them to get contaminated with dirt, grease etc. Next, remove the bolt that holds the brake hose to the mud guard with the 8mm socket:
Now that the brake hose is free, we can remove the calliper. It’s held to the front fork by two bolts. Time for the 12mm socket and breaker bar:
Note that Honda specify these bolts as being ‘ALOC’ and state that they should be replaced when you remove them. From what I can tell, they come from the factory with a thread locking compound, which I simply replace with blue Loctite 243 (non-permanent, chemical resistant – designed to hold the bolt in position but can be undone with hand tools). They may also be stretched and weakened when tightened, hence only having one use. I have reused these many times and have never encountered problems. I do not believe that they are torqued up tight enough to make them stretch (30Nm). I have also amusingly found that some people say that ALOC stands for Add Loctite Or Crash!
Now the calliper can be gently released. It is okay to let it hang on the hose if you’re careful not to suddenly drop it. Some folks use a bungee and hang it from the handlebar, taking the stress off the hose. Now we can split the calliper – the gold part (calliper body) separates from the black part (mounting bracket):
Depending on the condition of the calliper, considerable force may be needed to pull the two components apart. They could be seized together if the calliper has been neglected over a long period of time.
Once you separate the calliper from the bracket, you can also remove the pad spring (which might fall out anyway). Here are the spring and bracket – dirty, with remnants of grease on the slider pins:
Now our attention turns to the calliper itself. Observe the two round pistons and black rubber boots – filthy!
We need to do some cleaning. So, time to pump out the pistons. This needs to be done very carefully. Pull the brake lever and the pistons should move outwards. If only one piston moves, hold it down with your thumb and keep pumping, slowly and carefully, so that the other one moves out. Keep a careful eye on the brake fluid level in your master cylinder. DO NOT let it drop below the lower limit marker or you may get air into the system (this is bad!). We’re aiming to get both pistons about halfway out, so that we can clean them properly. You can do them one at a time if you wish.
Here’s what we get when they’re pumped out:
Now it’s time to clean everything up. Pay particular attention to the pistons and rubber boots. I use Wurth Brake And Chain Cleaner with my trusty old toothbrush and kitchen towel (which is very slightly abrasive, so well suited for this job) Wurth Brake And Chain Cleaner is safe on rubber components. Other brake cleaners may not be. If in doubt, you can use pure brake fluid, but be sure to rinse everything thoroughly with water when you’re finished as brake fluid will strip paint!
And when you’ve cleaned everything up, inspect the pistons carefully for pitting and corrosion. If they’re pitted, they can damage their seals and you could get a brake fluid leak which could be catastrophic. They will need to be replaced, along with the seals (which consist of two inner fluid seals and two outer dust seals). Check the rubber boots for any swelling, cracks or other damage and also replace them if needed. My calliper above is okay.
Now we clean the bracket and pad spring:
With the bracket, we have to pay close attention to the two slider pins, making sure they’re not pitted/corroded or damaged at all. Light wear to the paint is okay.
Let’s grease everything up. Apply red rubber grease to the slider pins and smear a thin layer around both pistons to protect against corrosion:
Red rubber grease is safe to use on or around rubber components, and it should not affect brake fluid either.
Now push both pistons all the way back in with your thumbs (or use a block of wood for leverage if thumb pressure is not enough) and reassemble the calliper by pushing both parts back together, ensuring that the rubber boots ‘hop’ over the lips on the bracket’s slider pins. You may need to syphon out some brake fluid from the master cylinder if you’ve ever topped it up in the past. Personally, I have never found the need to.
Next, re-mount the assembly back on the fork, remembering to clean up the mounting bolt threads and adding one drop of Loctite to each Torque them up to 30Nm:
Don’t forget the pads! Roughen up the friction material with some wet and dry paper, then clean them up with some brake cleaner:
Clean up the pad retaining pin (if it’s severely corroded or damaged, replace it), apply some red rubber grease to the o-ring and put some copper grease on the screw threads, as well as on the backs of the brake pads. Be extremely careful not to get any on the friction material! Applying copper grease to the pads will help protect the pistons from corrosion and can also prevent the brakes squealing when they’re used.
Now re-install the pads, starting with the right hand pad, remembering that its ‘hook’ must go over the lug of the bracket:
Next, reinstall the pad pin, making sure it passes through the holes at the bottom of both pads – torque it to 17Nm:
Finally, re-fix the hose retaining bracket to the mud guard – torque to 10Nm.
Now the brake can be tested for binding. Pump the lever until it becomes firm. Spin the front wheel by hand, it should turn relatively freely with little resistance. With a hard push I can get 1 to 2 turns from it. The pads will rub on the disc a little, which is normal. Spin the wheel again, applying the brake before it stops. Then, try to spin the wheel a final time – it should turn in the same way as it did when you first spun it. If the wheel is very difficult to turn, the calliper probably has a lot of internal corrosion and the seals will most likely need to be replaced. But if you follow this procedure at every service interval, that won’t happen for a very long time (17’500 miles for me and counting)!