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Offline RobZ900

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Calliper and master cylinder service?
on: February 22, 2021, 11:48:30 PM
Looking through the service manual and seen that the seals in the callipers and all rubber parts on the master cylinders are supposed to be replaced every 4 years, which is a couple of months away for me. Never done this job before, is there anything particularly difficult about it or anything to be aware of? Also read to use compressed air to remove the pistons (which I dont have access to) or piston removal pliers, but remember seeing a video of someone trying to remove pistons with this type of pliers and damaging the pistons. Any thoughts on this method?
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: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline zed9

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Re: Calliper and master cylinder service?
Reply #1 on: February 23, 2021, 03:20:18 AM
If you maintain your brake system by changing the fluid at least every two years and you clean the crud out from around the pistons.. you shouldn't need new seals for at least fifteen years. If this is your first time in four years, you're still good.

Buy yourself a Mity Vac and DOT4 fluid and you're good to go.
Here's a tip.. When you give the bleeder screws the final tightening up, use very little force. Barely any pressure on the wrench will properly tighten that bleeder screw. Finger tight (on wrench) is good. Don't grab it and pull.
Many people gorilla that screw and they damage the seat and threads, which makes the next bleed problematic.

If for some reason you need to replace the seals, there is a method for pumping them all the way out do that you can about pull them out with your fingers. If your brakes feel fine and the pads don't drag, you don't need seals.
Last Edit: February 23, 2021, 03:23:35 AM by zed9

Offline RobZ900

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Re: Calliper and master cylinder service?
Reply #2 on: February 23, 2021, 08:41:37 AM
Fair enough, brake fluid would be due at the same time as I changed it when the bike was 2 years old. Got another couple of months until its 4, so just started checking the manual to see what needs doing this year and saw it said to replace the brake hoses, and all the rubber seals for the callipers and master cylinders and thought Id ask. With that said, mine sees the worst of the weather, so perhaps its worth me at least taking the callipers off and giving them a good scrub.
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline Frontline

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Re: Calliper and master cylinder service?
Reply #3 on: February 23, 2021, 11:23:43 AM
*Originally Posted by RobZ900 [+]
so perhaps its worth me at least taking the callipers off and giving them a good scrub.
This is very important. Every couple of months I unbolt the calipers (hose still attached) and use a bucket of HOT soapy water (I use Dawn dish washing fluid) and scrub the piston areas really good. Another tip, I use a small cotton string (about 1mm thick) and wrap it around the piston and go back-n-forth scrubbing the exposed pistons. Another thing that helps is one you remove the pads, pump brake levers couple times to push pistons inward (this help gaining access to more piston surface area. After cleaning, I use old brake pads and a large flat blade screw driver to push pistons back in. You kinda need to push them in all at once so...

Optionally, I sometimes de-glaze rotors and lap the pads on dead flat surface (using 320 wed/dry).

The levers...I squirt a shot of AFC50 at piston and grease at fulcrum.

Offline RobZ900

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Re: Calliper and master cylinder service?
Reply #4 on: February 23, 2021, 12:55:49 PM
Well Ive still got another 5 weeks til Im back at work, so I suppose thatll give me something to do. Will order some new brake fluid and change it early while I dont need the bike too.
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline Cazzy_R

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Re: Calliper and master cylinder service?
Reply #5 on: February 23, 2021, 01:39:26 PM
*Originally Posted by RobZ900 [+]
Well Ive still got another 5 weeks til Im back at work, so I suppose thatll give me something to do.

I noticed you posted pics in he gallery of your headlight conversion.
How did that work out?  :027:
Tighten it 'til it strips then back it off half a turn.

Offline RobZ900

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Re: Calliper and master cylinder service?
Reply #6 on: February 23, 2021, 02:04:44 PM
*Originally Posted by Cazzy_R [+]
I noticed you posted pics in he gallery of your headlight conversion.
How did that work out?  :027:

Practically finished. Had to extend a wire to reach the battery, but Ive since put it on the bike and tested it. All working fine but the rubber dust covers for the back of the headlight werent deep enough so I cant finish putting it all together just yet. Expecting new dust covers this week, then just got to sort alignment. Was planning to do a write up once its all done. If you have a look at the pictures on my profile, youll see that the back of the bulb is sitting just proud of the dust cover.
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!

Offline zed9

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Re: Calliper and master cylinder service?
Reply #7 on: February 23, 2021, 02:38:05 PM
Here's a good method to clean the pistons.
Unbolt one caliper at a time. (Leave the other one on the rotor).
Get a wooden paint stirrer stick or facsimile such as pop sickle sticks. Then cut them long enough so they cover both pistons. Stack  them thick enough so that they just fit inside.
Now pump the lever until you squeeze the sticks. Release the lever. Then remove one stick at a time then pump the lever. Repeat until you have two sticks. You could probably leave only one stick but two is enough to get the pistons clean.

This allows all the pistons to come out of their bores evenly.
You should note how they come out. They won't come out perfectly together but they should be close. The stickiest one will come out last. Also, once you release pressure on the lever, the pistons should release their grip ever so slightly on the sticks. This shows that the rubber seals are doing their job of deforming and pulling the pads slightly off the rotors.

Then do the other side. If you attempt both sides together you risk sucking air down the lines via the master cylinder.
After the cleaning is done, push the pistons back in their bores then change your fluid.

Online 3alfa3

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Re: Calliper and master cylinder service?
Reply #8 on: February 23, 2021, 10:43:44 PM
*Originally Posted by RobZ900 [+]
...mine sees the worst of the weather, so perhaps its worth me at least taking the callipers off and giving them a good scrub.

First rinse with COLD water if you ride on salty roads.
Last Edit: February 23, 2021, 10:44:30 PM by 3alfa3

Offline RobZ900

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Re: Calliper and master cylinder service?
Reply #9 on: February 23, 2021, 10:59:28 PM
*Originally Posted by 3alfa3 [+]
First rinse with COLD water if you ride on salty roads.

It gets treated with ACF50 a few times a year and hosed off after use in the winter with a wash every couple of weeks.
Motorcyclist - noun (moh-ter-sahy-klist)
: a person willing to take a container full of flammable liquid, place it on top of a hot, moving engine and then put the whole lot between their legs!