Changing brake pads

Changing brake pads is an easy task. So if you are just learning how to work on your bike (what you are because you wouldn’t read this article otherwise), this is a good place to start. All you will need are normal hand tools, and perhaps an impact screwdriver if you have a Yamaha.

Inspecting The Brake Pads

This should be done after every ride and before every race. What you are looking for is the amount of pad material left before the metal pad backing touches the disc.

Pads wear at different rates, depending on conditions, rider, pad material and make of calliper etc. So a certain amount of experience helps to judge when changing brake pads is necessary. The guiding rule - as always is - when in doubt change them.

For a normal social outride, I ensure that there is 2mm of pad material left. For a normal social ride in muddy conditions I am happy with 3mm of pad material. A long national offroad will require brand new pads, as will a muddy race. If you keep an eye on the pads you will soon know when to change them.

Another reason for changing brake pads is when they become contaminated with oil. You’ll notice straight away as thay stop working! At the front this happens when a fork seal is damaged and fork oil runs into the calliper (how to avoid leaking seals). At the rear a damaged clutch cover or damaged inner clutch gasket can leak oil backwards down the swingarm. There it drips onto the disc and is carried into the calliper. If this happens, changing brake pads is the only way to go. There is no hope of getting them right by cleaning with solvants.

Removing The Old Brake Pads

Brembo calipers (KTMs and other Enduro bikes)

Front: At the bottom of the caliper you will see two small R clips securing a pin. Pull the R clips out with pliers, and remove the pin through the spokes.

The pads can then be pulled out. If the pads won’t come out, use a screwdriver to slightly separate the pads, then pull them out with pliers. Remove the shim from the piston-side pad. Clean the pin and check it doesn’t have deep grooves in it. If uncertain, order a new pin.

Rear: Exactly the same procedure is followed as for the front.

Nissin (Yamahas, other Jap bikes are similar)

Front: At the back of the calliper you will see a black setscrew, slotted for a normal flat screwdriver. Unscrew it. Note: if this screw has been neglected it will have rusted into the calliper and will have to be smacked out with an impact driver.

Underneath the setscrew you will find a 5mm Allen socket head at the end of the brake pin. Put your Allen key into the screw, and give the back of the Allen key a couple of taps with a light hammer to free it off. Now unscrew the brake pin, withdraw it and remove the pads. Remove the shims from the pads. Inspect the pin and replace if necessary.

Rear: Exactly the same procedure as for the front.

Fitting new brake pads

  1. With contact cleaner, brake cleaner or thinners, carefully clean the brake disc and the calliper. Wash any oil or grease off your hands.
  2. With a screwdriver against the disc, carefully push the piston back into the calliper. Note that in the front calliper there are two pistons, and as you push one in, the other will come out. You will have to move both out of the way.
  3. Fit the shims onto the new pads. They will just clip on.
  4. Start with the pad that will be located first by the pin. That way you are not juggling two pads and the pin. Slide the pad into the calliper and ensure it locates in the slot at the front. Push the pad up against the spring clip in the top of the calliper and push the pin into the hole in the pad.
  5. Fit the next pad and slide the pin home. If the piston is sticking too far out to fit the second pad, you may have a hydraulic lock in the system, caused by an overfilled brake fluid reservoir. If this happens, loosen the cap of the reservoir and remove some of the fluid with a clean cloth.

Brembo calipers

Once you finished changing brake pads, the R clips can be pushed home. They can then be safety wired in various ways. The first way is to wire the two clips together and to the brake hose. This means that you can come screeching into the pits, your mechanic can pull the safety wire so both clips come out at once. Then he can remove the pin and fit new pads in a couple of minutes.

It also means that if you crash through vegetation, clips can be pulled out, the pin will drop out followed by the pads and there you are, in the middle of the bush with no brakes.

I prefer to wire the two legs of the outside pin together so that no passing bush can pluck the pin out. How you wire the pins will depend on what you are doing. Top riders at the Roof will wire their clips together for a fast pad change after the Round The Houses and before the time trial. You decide.

Nissin Calipers

Before you screw in the pin, put a dab of Copaslip on the threads, and on the threads of the setscrew so dis-assembly is easy in the future.

Finally

Before your test ride, pump the brakes several times till the lever comes up hard. We know somebody who went off in shorts after changing brake pads. He was going to pull a wheelie and impress his buddies. It was a wicked wheelie till he tried to use the back brake. That was an almighty roasty on his bum - we were impressed! So double check all your work!

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