Front Brake Calipers

[yamaha1300rider]

For those of you yet to tackle this task here are my observations for what they are worth:

1. My calipers have just had their first clean in 21k miles (5 years) - BIG MISTAKE! If you have rain in your county do the clean up every year. The pistons were difficult to clean and rusty at the edges

2. Next year when I have a brake fluid change I will replace pistons and brake pins - shims seemed ok

3. R clips in uk very expensive GBP 2.25 each!

4. Dirt on shims had removed the arrow showing direction so need to note before removing or copy other caliper

5. A fraction of the piston is difficult to reach even with a toothbrush and I could not figure out how to turn the pistons

6. I did not know how far the pistons could be moved out (without popping out completely) by pressing the brake lever as I have never held a piston - perhaps someone could confirm

7. No need to open bleed nipple as suggested in service manual as pistons could be pressed back by hand

 

[C&C]

7. No need to open bleed nipple as suggested in service manual as pistons could be pressed back by hand

It's a good idea to open the bleed nipple, when pushing your pistons back in because this allows some of the dirtiest fluid to escape out the nipple instead of being pushed back into the caliper. Usually this isn't a major problem but it is good practice to remove the dirtiest brake fluid out, not back into, service. Not a bad idea to bleed the system anyway.

 

[yamaha1300rider]

Makes sense what you say C&C although presumably the brake fluid must be constantly on the move??

Anyone know how far the brake pistons can be pressed out before a full bleeding is required?

 

[C&C]

Makes sense what you say C&C although presumably the brake fluid must be constantly on the move??
Anyone know how far the brake pistons can be pressed out before a full bleeding is required?

It moves but it doesn't circulate. That nasty fluid is going to pool in and around the moving parts in the caliper.

As far as when bleeding is required, when pushing pistons back, only if air gets into the system. Though a brake bleed is easy enough to do that whenever I'm into the brake system, I bleed.

 

[Geezer]

The biggest problems with brake fluid are heat and moisture.

Heat from braking transfers to the fluid inside the caliper and the fluid breaks down.

Brake fuuid is hygrospopic, meaning that it absorbs water. Over time, even in the closed system of your brakes, enough moisture gets into the system to get the brake fluid 'wet' over time.

So, you need to replace the brake fluid from time to time. Once a year is normally a good interval, but any time you work on the brakes it is a good idea to freshen it up by letting the old burned stuff out the caliper and putting fresh in the reservoir.

Keep in mind that brake fluid is nasty stuff and will damage your paint if you get it on there so be careful and don't use rags with brake fluid on them to wipe painted parts of your bike.

 

[yamaha1300rider]

Thanks for the feedback

Re my question "Anyone know how far the brake pistons can be pressed out before a full bleeding is required? ",

I'm not explaining myself very well so I'll try to rephrase.

When cleaning the calipers we are advised to press the brake lever/pedal to bring the pistons out of their recess. How far out of the recess before they pop out and a rebleed is necessary e.g. 1/4in, 1/2 in, 1in etc?

TIA