Rear Brake Update


Basically, I have lost the rear brake a number of times now and the fluid simply will not hold its state. The rear brake became unreliable and unpredictable so I got the upgrade kit from the dealer and got cracking.

The kit includes the following parts:

1 x redesigned master cylinder complete.
2 x slave cylinder pistons (with plugs on the pad side, unlike the originals).
1 x set slave cylinder seals (2 dust seals and 2 fluid seals).
4 x copper washers.
1 x 250 ml tin of DOT 5.1 fluid.

The part number for the kit for my 2004 bike is: '600 131 000 00'. It's called a 'BRAKE-KIT U1'

Start by loosening the forward hose bolt being careful not to damage the wires on the rear brake switch (they are very fragile after 30,000miles of fun!).

Remove the lower pin assembly.

And remove the master cylinder.

Now fully remove the forward hose bolt carefully, again trying not to break the brake switch wires .

Now remove the rear brake line bolt on the caliper. You can leave the hose in position on the swing arm.

Now you will have to remove the rear wheel in order to remove the caliper.

Remove the toasted old brake pads that should have been replaced 3000 miles ago! Or the perfectly good ones which you should have?!?

Separate the caliper from the holder (just pull them apart).

Pull the old pistons out of the caliper. You will have to wiggle them a bit as you pull, they are tight. I would recommend cleaning the caliper thoroughly first as to not get any dirt inside the body of the caliper. I was rushing!

Get the new seal kit to the ready including install.

Remove the old seals from the caliper with a small screwdriver or similar.

Make sure the caliper is all nice and clean, especially inside the body.

Liberally lube the new seals with the assembly fluid and install them as shown into the caliper. The (larger) square seals go in the rear grooves and the double lipped (smaller) seals go in the front grooves. Careful as to not damage the seals in any way.

Lubricate the new pistons with the same assembly / installation grease provided in the kit.

Gently push the pistons into place with the black plastic vent cap towards the brake pad as shown.

Check the rear brake pad holding pin for wear and replace if necessary (like this one).

Reinstall the brake pads in the reverse order that you remove everything. Remember the retention ‘R’ clip. I like to clean and apply copper grease to the stainless brake pad sliders and the brake pad pin as ‘seize prevention’.

Reinstall the rear caliper and connect the hose using two of the new copper crush washers provided in the kit.

Install the new master cylinder in the reverse order to removal, use the remaining two new copper crush washers provided in the kit.

It’s a good idea to turn the brake switch/bolt anticlockwise a few turns before installing the forward part of the hose to the master cylinder. This will ensure the wires are not all bound up and twisted when installed. Make sure everything is tight.

Its also a good idea to zip-tie the rear brake switch wire to the frame her to prevent it from melting on the exhaust.

Remove the master cylinder reservoir cover. Just out of interest, note they have finally redesigned the awkward to install rubber volume device.

Fill the master cylinder to the max line shown on inside rear face of the cylinder and bleed accordingly. When fully bled, ensure fluid level is right on this max line. When you install the volume device the fluid will be dead level with the top of the cylinder.

Re-install the volume rubber and master cylinder cap.

DONE, with photographs in less than 30 minutes! Took me longer than that to write this!

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