CAUTION

• Under no circumstances should you do anything that might scratch or
  damage the chrome 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
  person.
• 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.
  
• Once a seal has been broken new seals should be fitted.
  
• 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
  unreliable.
  
• If you score or scratch the caliper where the piston seals are fitted
  then the system will probably leak.
  
• 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 "leak" 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).
  
• Once the caliper pistons have been ejected from the caliper body
  the old oil and dust seal have to be discarded and new ones fitted.
  
• 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 it.
  

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".
  
• Special grease for brake caliper rebuilds.
  
• 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:
  

  Large piston:
  

  • Diameter: 32mm
  • Length (without cap): 23.5mm
  • Length (with cap): 25mm

  Small piston:
  

  • Diameter: 30.1mm
  • Length (without cap): 23.5mm
  • Length (with cap): 25mm

PROCEDURE.

1. Swing the brake caliper off the disc.
   
2. Using the brake lever, pump out the caliper pistons as far as you can
   without ejecting the pistons from the caliper.
3. Disconnect the brake hose from the caliper and bring it to your work bench.
   
4. Position the hose so that it doesn't leak.
   
5. Remove the plug, pin, spring pad and brake pads.
   
6. 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.
7. Seperate the 2 parts of the caliper body and remove the 2 joint seals
   (rubber washers).
8. 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.
   
9. If you are reusing the pistons you must clean them, then completely
   remove any cleaner residues.
10. If there is pitting on the chrome then the piston should be replaced
    but if thats not possible then remove and sharp edges that might damage the seals.
11. 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
    
12. Gently clean out any dirt from where the seals are fitted with fresh
    brake fluid.
    
13. Liberally coat each new seal in brake fluid (or special grease) and
    then install it, make sure the seal fully sits into it grove because if it
    doesn't then you might nick the new seal later when you are installing
    the piston.
    
14. After the seals are fitted coat the seals in fresh brake fluid
    (or special grease)
    
15. Coat the sides and edges of each piston with brake fluid (or 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
    gently.
    
16. Fit new joint seals and check that the metal that the seals touch is
    smooth and clean.
    
17. Apply "thread locker/sealer" or "copper grease/anti-sieze compound" to
    the threads of the caliper body bolts (Honda reccomend thread locker).
    
18. Install the bolts and tighten them in a criss cross pattern in 2 or 3
    steps, 15 Nm.
    

    Note: Althought the 1988 Honda manual reccomends coating the caliper
    seals in brake fluid some now reccomend sprecial grease.