Is there a shortcut to cleaning the return hole on Non ABS rear Master Cylinder, ST1100 2002 Non ABS?

[PhotoDoctor]

On the front master cylinder sometimes it’s possible to clean the return hole with a torch tip cleaner or small piece of wire. Does anyone have a shortcut method to clean the return line on the rear master cylinder? The symptom is the rear brake pretty much locks up after using a few times and cracking the bleeder nipple will release the pressure and brakes are free again. Thus we know it’s not the caliper.

I may have to pull the peg mount and remove the master cylinder and do a full clean and maybe a seal kit while there, but if there is a shortcut I’ll try it.

Thanks

 

[Ron]

Did you look at the pistons? Sometimes they get corroded and won't slide back in. You can clean them but replacements will be in your future.

 

[ChriSTian_64]

[...] The symptom is the rear brake pretty much locks up after using a few times and cracking the bleeder nipple will release the pressure and brakes are free again.

Did you look at the pistons? Sometimes they get corroded and won't slide back in.

Yeah, I agree with Ron.
Last summer, as a new ST1100 owner, I had that exact same issue. On center stand, I noticed my rear wheel wouldn't turn freely. Then @paulcb told me about the shoestring method.

See the picture of the pistons of my rear caliper ? All shiny, right ?
( the piece of blue wire is just holding the caliper in place while I'm working on it ).



They were not like that before. They were all black covered by a layer of grimme, gummy stuff... probably some rust too.
So they could get out but could hardly get back in.
So the shoestring method is very simple. You take a clean shoestring, dip it in clean brake fluid, pass it around one piston ( with brake pads removed) and holding a shoestring end on each hand, you just polish them, working your way around.
I can tell you the juice that was dripping from there was pretty dark.

It only took me a few minutes by pistons. I then pushed them back in a little (it helped to put the wheel disk back in, between the pads).

And that was it. Problem solved.

 

[Upt' North]

Mike, I probably agree with you that it's not the caliper and +1 @The Cheese it could also be a collapsed brake hose. Also +1 I wouldn't attempt a quick fix.
It's probably time to give it a good looking at, it isn't too difficult to get at and you will have the reassurance of knowing it's right.
Hope it helps.
Upt'North.

 

[PhotoDoctor]

The return hole was plugged and it took my smallest jewleler's drill bit to clean it out. Brake fluid sitting for 11 years had it plugged solid.

 

[jfheath]

Thanks for the feedback.
For future reference - is the hole accessible from the feed from the reservoir - ie after part 8 has been taken off , or was it necessary to take out the piston ?

 

[wjbertrand]

I had the exact same problem with my old VF750 interceptor. No shortcut that I could figure, these cylinders are damn simple. I just disassembled the MC and had to manually clear that little hole with a bit of wire. I blasted it afterward with copious amounts of brake cleaner and then reassembled with new seals. Problem solved and I resolved to change the brake fluid more often after that. The whole system was full of white pasty deposits due to my lack of maintenance.

 

[PhotoDoctor]

Jf - you can get to the relief hole after you take part # 8 off but it's not much help as the piston and spring will prevent you from being able to push a tiny bit or piece of wire through the hole and confirming that all is clear. (I did try that with the cylinder still on the bike, then I tried again with the cylinder off the bike and not removing the piston, no joy until I took the piston and spring out)