Front brake caliper rebuild.
- Under no circumstances should you do anything that might scratch or
damage the finish on the pistons in any way. (Don't try to pull the pistons
out with a pliers).
- Use only DOT 4 brake fluid as anything else may cause brake failure.
- DOT 4 brake fluid is hydroscorpic which means it absorbs water,
thus you should only use brake fluid from a sealed container
- Do not allow foreign material to enter the master cylinder resevoir
while filling it.
- Brake fluid can damage paint, plastic and rubber.
- Hydraulic brakes should only be serviced by a trained and expierienced
- If the brakes are "spongy", leaking or have any defects whatsoever
then the motorcycle is not safe to drive.
- If brake fluid or and other substance contaminates the brake disc
then it will need to be cleaned with "brake parts degreaser".
- If brake pads become contaminated with brake fluid or any other
substance then they should be discarded.
- Do not mix different types of brake fluid.
- After servicing the brakes: inspect and test the brakes before taking
the bike on the road.
- If any of the threaded components (eg: caliper body bolts, bleed
nipple, hose connection etc) are damaged then the front brake system is
- Do not bend or twist the brake hose (Inspect the hose for cracks or
any signs of damage).
- Do not hang the caliper off the brake hose.
- Do not apply grease on the friction surface of the brake pads.
- Do not apply an excessive amount of grease on the back of the brake pads
as it might creep onto the friction surface of the pads or disc.
- Brake dust may contain asbestos fibres that can and will cause
diseases such as CANCER.
- Take whatever steps are necessary to avoid inhaling brake dust (Never
use an air brush).
- If you use compressed air to push out the pistons then the pistons
will shoot out like bullets.
- Keep the caliper on or wrapped in a towel to prevent scratching
WHAT YOU NEED
- The usual tool: spanners, allen keys etc.
- A full set of "piston seals" and "dust seals" and two "joint seals".
- 500ml of DOT 4 brake fluid and brake bleeder equipment.
- An "E12 female torx socket", usually comes in 3/8" drive.
- Air compressor or "motorcycle brake caliper piston removal tool".
- Red rubber grease, I find that red rubber grease dries out after
a few days so I mix a small amount of brake fluid thru it so it stay
wet a little longer
- You may need new pistons, the J model bros has different pistons to
the K and L bros, They are basicly the same piston but the J model piston
accepts a "piston cap", Honda no longer manufacture the J model piston, it
has been superseded to the K-L piston. The dimensions of the J model
pistons are as followes:
- Diameter: 31.948 mm - 31.998 mm, service limit: 31.94 mm
- Length (without cap): 23.5mm
- Length (with cap): 25mm
- Diameter: 30.148 mm - 30.198 mm, service limit: 30.14 mm
- Length (without cap): 23.5mm
- Length (with cap): 25mm
- Swing the brake caliper off the disc.
- Using the brake lever, pump out the caliper pistons as far as you can
without ejecting the pistons from the caliper.
- Disconnect the brake hose from the caliper and bring it to your work
- Position the hose so that it doesn't leak.
- Remove the plug, pin, spring pad and brake pads.
- Using an "E12 female torx socket" remove the four caliper body bolt
in a criss cross pattern in 2 or 3 steps.
Note: If thread locker was used on the bolts last time it may be difficult to
remove the bolts.
- Seperate the 2 parts of the caliper body and remove the 2 joint seals
- To remove the pistons for the caliper body, you can use
a "caliper piston romoval tool" or you can use compressed air. I used
compressed air, when the pistons release they will shoot out like bullets
so wrap the caliper in a towel and place it in a vice so that the jaws of
the vice will stop the piston from shooting out. Invariablely one piston
will come out easier that other so close the vice enough to prevent that
piston from fully ejecting from the caliper, this will allow the compressed
air to push out the other piston. Apply compressed air to one of the ports
while sealing the the other ports, the piston should now come out.
If you are dealing with frozen pistons then you will need the Laser
brake piston removal kit. Applying heat with a blow torch might help
the pistons come out a little easier. The J model piston can be tapped
with a M16 to help pull it out.
- If you are reusing the pistons you must clean them, then completely
remove any cleaner residues.
- If there is pitting on the nickel then the piston should be replaced
but if thats not possible then remove and sharp edges that might damage the seals.
- Use a small pick to pull out the old seals, be carefull not to scratch
the caliper as that would cause a disaterous leak later
- Gently clean out any dirt from where the seals are fitted with fresh
brake fluid. If there is severe corrosion inside the seal groves
then you will have to remove it with a pick and small rotary wire
brush. If the seal groove is full of corrosion then the anodised layer
has failed so you dont really need to worry about damaging it.
- Liberally coat each new seal in special grease
- After the seals are fitted coat the them in special grease
- Coat the sides and edges of each piston with special
grease) and install it by pushing it in, if you push the piston in at an
angle you might nick one of the new seals, push the piston in straight and
- Fit new joint seals and check that the metal that the seals touch is
smooth and clean.
- Apply "thread locker/sealer" or "copper grease/anti-sieze compound" to
the threads of the caliper body bolts (Honda reccomend thread locker).
- Install the bolts and tighten them in a criss cross pattern in 2 or 3 steps,
- Honda recomend tightening the bolts to 15 Nm when thread locker is used,
however, if threadlocker is not used then a higher torque of 23 Nm might be