12GS Rear brake piston/pins removal and clean

[rup5555555]

One of my rear pistons is sticking, I want to remove it and clean it up but,

Do I need to replace the rubber seals if I remove the piston?

Will I need to bleed the rear brake circuit after?

What is best way to clean the surface of the piston? (I have tried brake cleaner and toothbush but I does not help)

Also it does slide on the pins anymore, how do I remove and lube the pins?

Thanks

 

[DrFarkoff]

Ehm To be Honest If you are asking these many questions about servicing your brakes?

May I suggest that you book into Steptoes Workshop at his earliest convenience

 

[Pukmeister]

Will I need to bleed the rear brake circuit after?

STEP AWAY FROM THE BIKE, NOW !!!!!!!

 

[rup5555555]

Adam, did you use the brake fluid tool I sent you?

Anyway, I am plenty competent - just haven't serviced a caliper before so any experience from the forum would be excellent. You have to start sometime

So forget those questions. I know how to bleed the circuits. But the advice I really need is how get the caliper unstuck move on the pins - what is the technique?

 

[autogs]

dont take the pistons out,remove pads and caliper and then pump brake,not enough to pop pistons but enough to clean up the corroded area.

 

[rup5555555]

Thanks got it! The piston now can be pressed back into the caliper (all be it very stiff compared to the other one),

But I'll think I will give up on this one because the caplier is not sliding on the pins and thus I can't get the new pads in,

There goes the bank holiday camping trip

And to add insult to injury I popped out the good piston too far so I guess to should have taken the advice....now the brakes have to be bled, but on the bright side it is a good opportunity to change the fluid.

 

[Spout]

Here ya go mate:

http://advwisdom.hogranch.com/Wisdom/BFDRear2.1.1.pdf

 

[rup5555555]

Thanks alot Spout, very educational I will use this to do more damage to my bike tomorrow

 

[Bem]

Here ya go mate:

http://advwisdom.hogranch.com/Wisdom/BFDRear2.1.1.pdf

Forgive me if I have missed something here but:
I managed to get as far as page seven before I fell asleep, noting that this link with pictures appeared to refer to a 11/1150 rather than a 12 (which is what the man wants). As we do not know if this is a Servo 12 or not surely this link is a bit misleading, not to mention potentially dangerous to a confessed person of limited experience?
just my tuppence worth.

 

[rup5555555]

I was very interested in page 27 where it tells me how to separate the carrier and caliper, if I can get the two apart then I can clean it up enough to ride to Jap and German or Steptoe to do a full fluid change...

 

[DrFarkoff]

To be honest the rear piston that is stiff needs to come out

If it's sticking then there is a restriction !

And in this case More than likely it is due to salt

You need to remove pistons Clean out salt Usually mostly behind the outer "wiper" ring and in its groove and give it light coat of rubber grease on reinstallation (but while you are in there check behind the other rings in case salt is pushing them against the piston too!

Be VERY careful as servo brakes are usually 4 circuit! 2 control ciruits and 2 wheel circuits

If you run the fluid out of the servo pump You will shag the servo unit!

If you run fluid out the nipple you will need to recharge brake fluid at the servo NOT the reservoirs at the master cylinder <--- I will confirm in morning

 

[Pukmeister]

Rupert, I used the brake filling adapter once, but have now traded my beloved old 1200 with servo ABS in for a newer 1200GSA with non-servo ABS.

A bit of piss taking on my part but obviously if you remove the piston from the caliper you will need to bleed it afterwards and as stated, it will be a full servo system bleed/refill then the pilot circuit.

 

[rup5555555]

Well, I got it sorted, Steve and Tony down at Jap and German did a great job it took a blast from an oxy-acetylene torch to get it open on the front guide pin. They all did a full fluid change at the same time, all in all a great performance from the Welsh boys

Thanks for all the help on this one