Cleaning rear caliper - 06 Girly

[cosmo]

Since it seems that the rear caliper, in particular, seizes on my bike, I have come to realise that regular maintenance will include a strip and clean, so here's how:

First, remove the pins guiding the pads, then remove the caliper mounting bolts. 5mm for the pins, 14mm for the bolts.

One pad will drop out, prepare for that (catch it). Place a pan under the caliper, away from the bike as much as possible. Next, pump the pedal watching the pistons. Leaving the one pad in will limit the travel usefully. When the pistons have extended to the pad, or nearly so, remove that pad. Now carefully pump the pedal to fully extend the pistons. The key is that the pistons will extend to the other side of the caliper (and then fall out), you are trying to make them do that simultaneously, making removal easy. Place the pistons in a safe location.

Place the caliper on the mount, and loosen the brake pipe (14mm). Remove the banjo bolt, being careful not to lose the sealing washers. Place the caliper in a safe place.

Now, polish the pistons to remove grunge. If there is rust, and it is contained within the first 2-3mm of the top of piston, polish that off as much as possible. Any more, and the piston may need replacement.

Next, remove the two rubber seals per bore. Use a wood or plastic tool for this. Then lightly hone the bores of the caliper. I use a three stone hone, available at most motor factors. Brake fluid is used as a lube, probably some left in the bore. Clean swarf with a brake clean spray. Do not use flame with brake cleaner (seriously, the fumes are quite deadly). Replace rubber seals after wiping clean.

Using brake fluid again as a lube, replace pistons in caliper, closed end first.

Reinstall pads and caliper in reverse order.

Bleeding can be done in your favourite manner. I have used both gravity and pumping to good effect. Just depends on time.

Signs that your caliper is seized (or in process of): Hard to back up. Fuel mileage lessening. Rotor very hot after riding. Pad life measured in meters, rather than kilometers.

Good riding,
Cosmo

[metalguru]

Nice write up there.
The only thing I would add to an already comprehensive description would be that when the pistons are out and the cleaning up has been carried out is to clean out the grooves the seals sit in as these will be full of corrosion, incidently the main reason for the brake binding, of course replace the seals and if using a hone go steady, don't want to take too much metal away.

[daveb]

Bleeding can be done in your favourite manner. I have used both gravity and pumping to good effect. Just depends on time.

I use a syringe and a tube fitted to the bleed nipple and pull the fluid down from the reservoir, you will see the bubbles getting smaller and smaller. its easier than pumping the fluid down, and doesn't take long.

[Bixxer Bob]

I have a vacuum bleeder I bought 6 months ago.  Haven't had a chance to use it yet though ...

[daveb]

I have a vacuum bleeder I bought 6 months ago.  Haven't had a chance to use it yet though ...

mines the el-cheapo manual (home-made) version

[Bixxer Bob]

http://www.ffx.co.uk/tools/product/Vs4022%20Vacuum%20Tester%20And%20Brake%20Bleeding%20Kit%205051747695689%20Vs4022

[metalguru]

That is an excellent kit there BB, it can have many uses, even use mine for setting fork oil level with a snorkel tube depth guage made from copper brake pipe, great for setting vacuum guages too with the 'T' pieces provided.

[cosmo]

I've used the vacuum pump, works better if you coat the threads of the bleeder with anti-sieze, to prevent air being pulled around the threads.

Cosmo

[Bixxer Bob]

I've used the vacuum pump, works better if you coat the threads of the bleeder with anti-sieze, to prevent air being pulled around the threads.

Cosmo

Good idea!