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Brake Caliper Maintenance


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Required tools :
  • One ¼ inch twelve point socket for the pad pins​
  • One ten millimeter twelve point socket holds the caliper halves together​
  • One ¼ inch ratchet wrench​
  • One flat head screw driver​
  • One Phillips screw driver​
  • One high quality spray can brake cleaner​
  • One torque wrench​
  • Lyndall Z pads are used here.​
  • One bottle of the proper Harley-Davidson brake fluid for your bike​
There are two bolts holding on each caliper on Harley-Davidson motorcycles, there are also two pins that hold the pads in place. If your motorcycle has two front calipers, start by removing the caliper furthest away from the master cylinder, which on most motorcycles is the one on the left side of the motorcycle, or in other words on the side of the clutch lever.

The first step is to loosen the two pins that hold the pads in place with the ¼ inch twelve point socket. Once this has been accomplished, remove the two bolts that secure the caliper to the front forks with your ten millimeter twelve point socket.​

The caliper can then be gently removed from the rotor by pulling the caliper towards the rear of the motorcycle.

Once the caliper has been removed, turn the caliper over so that you can see the condition of the pads. Leave the pads secured within the caliper and have someone else assisting you to pull on the front brake level. As they do so, notice how the pistons in the calipers are moving as hydraulic pressure is applied as the brake lever is depressed. The likelihood is that the pistons that are closest to the source of hydraulic fluid will move initially while the pistons that are furthest away from the source of hydraulic pressure will in all probability hardly move at all.

This is due to a number of factors, the first being that all of the pistons in a Harley Davidson caliper are virtually the same size and the further the piston is away from the source of hydraulic source the more pressure that it would require to move at the same rate as the pistons move that are closer to the source. The only way that this can be accomplished where both pistons front and rear move at the same rate is with differential bore, meaning that he pistons furthest away from the source are smaller in diameter so that less hydraulic pressure is required to move them as freely as the pistons move that are nearest to the source of hydraulic pressure.

The other problem that causes pistons to drag and hang-up is that since there are no dust boots on the pistons, brake dust and general road dirt accumulates around the pistons and caused them to drag and in some instances to become completely inoperable. This is why you might notice why your brake pads wear so unevenly once they have been removed from the caliper.

After noticing how little some of the pistons move, place a pan below the caliper and then take your can of high quality brake cleaner and spray a strong stream of cleaner directly all around the pistons. If there is a build up here on the pistons, a shoe lace used in a see saw motion around the piston will help to remove the buildup here as seen below.

The retraction of the pistons into the calipers is very important and should be done with the shoe lace after spraying some brake cleaner in the area so that the brakes do not hang up and wear prematurely.

Once the brake cleaner spray has successfully removed all of the debris, take your flat headed screw driver and place the blade in between the old pads and force the pistons back into the caliper. Have your assistant pull on the brake lever once again and repeat the process as described above until all four pistons move relatively freely.

Once you are satisfied in their performance remove the two pins that secure the pads in place with the ¼ inch twelve point socket. Once the pins have been removed, gently remove the pads that were secured within the caliper. Take notice of how the pads were installed since they are different in configuration.

Install the two new pads, once in place re-insert the two pins loosely until the caliper has been re-installed on the rotor and torque them after everything is in place.

Gently spread the two pads apart with your fingers until there is sufficient space between the two pads to allow you to re-install the caliper on the rotor. Once the caliper has been successfully re-installed place a few drops of Blue Locktite (242) on each bolt and tighten each bolt between 28-38 pounds of torque. Once they have been tightened install the 1/4 inch twelve point socket and tighten the two lock pins that hold the pads in place.

After you have successfully accomplished all of what has been outlined above, top off the master cylinder if necessary with the proper fluid by removing the master cylinder cover with a Phillips screw driver or a torx tool of the proper size, once the cover is re-installed pump the brake lever until all of the air has been removed from the system. I have found that after pulling on the lever a number of times if you flick the lever a number of times as well you will notice that there will be little movement in the lever before full pressure can be applied to the pistons.

Some additional things,

1) When disassembling, lay the pins and fasteners parts out in order and position removed so they go into the original positions similar to the exploded diagram shown in your HD service manual.

2) Check all contact sliding surfaces for wear, pitting or metal displacement, if a groove is visible or felt, replace them.

3) Do not forget to lubricate the pins with high temperature grease as recommended in your HD service manual.

Source: Lyndall Racing Brakes
I found you guys via google from England cos I needed some torx sizes for my 02 road king's rear caliper and thought it might help someone else to know that although the 10mm 12 point socket worked a treat I struggled to get a 1/4" 12 point socket to fit in the tight space I had around the torx head, so after a bit of rummaging around I found a 12 point 4BA ring spanner fitted and got them both out.

Once they were out I discovered the 1/4" was way too big.

Hopefully this MIGHT help someone out in the future.
It's a good idea to replace them but if you are stuck they can be reused but it is better to replace them