V50 Rear Brake Master Cylinder Overhaul

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   Dear All,
Back again I'm afraid, this time after successfully getting the calipers apart (eventually) I'm now trying to dismantle the rear brake cylinder. According to the w/shop manual you are supposed to remove the operating lever - the pivot pin on mine is seized solid. 
So, I thought I'd try move the lever out of the way and try to move the piston anyway. I found a bradawl that's a bit narrow but I thought would do the job.   Poking this up the pipe end and hitting it a lot harder than suggested by the manual produces no movement of any kind. Hitting the other ( lever ) end with a suitable drift also produces zero movement.

Am I missing something or do I simply need another one? I would have thought it should show some sign of movement as it needs to in order to move fluid...

Thanks,
Adrian
Bristol UK

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AdrianW Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 05 May 2019 Location: Bristol Status: Offline Points: 1208	Post Options Post Reply Quote AdrianW Report Post Thanks(0) Quote Reply Topic: V50 Rear Brake Master Cylinder Overhaul Posted: 24 Jul 2025 at 17:13
	Dear All, Back again I'm afraid, this time after successfully getting the calipers apart (eventually) I'm now trying to dismantle the rear brake cylinder. According to the w/shop manual you are supposed to remove the operating lever - the pivot pin on mine is seized solid. So, I thought I'd try move the lever out of the way and try to move the piston anyway. I found a bradawl that's a bit narrow but I thought would do the job. Poking this up the pipe end and hitting it a lot harder than suggested by the manual produces no movement of any kind. Hitting the other ( lever ) end with a suitable drift also produces zero movement. Am I missing something or do I simply need another one? I would have thought it should show some sign of movement as it needs to in order to move fluid... Thanks, Adrian Bristol UK

paulbricey Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 23 Dec 2019 Location: Stockport UK Status: Offline Points: 825	Post Options Post Reply Quote paulbricey Report Post Thanks(0) Quote Reply Posted: 24 Jul 2025 at 18:13
	I think there may be two variants of rear mastercylinder (or maybe 2 variants of the kit depending whether it's front or rear); One with a circlip, and one with a ring.....I guess you should be able to see a circlip BUT then you probably need to remove the pivot for ease to see it. Either way I'm sure it will take a big push/good thump...& I'd be inclined (at least to see) to find a way to press it in a large vice or similar because it's easier to see if it moves even a bit as you apply press, compared to whacking it. But you are right, the Lavera instruction suggests it should pop out easily (if there isn't a clip) Paul Edited by paulbricey - 24 Jul 2025 at 18:19
	Griso 1200 8V, V50

AdrianW Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 05 May 2019 Location: Bristol Status: Offline Points: 1208	Post Options Post Reply Quote AdrianW Report Post Thanks(0) Quote Reply Posted: 25 Jul 2025 at 17:41
	Thanks Paul, I'm pleased to report that after a session of applied violence and oil I got the lever pivot pin out! This confirmed that it was the ring type (you could see better then!) so more of the above was applied (just the violence this time!). Special Tool 14 92 64 00 was replaced by a 70 plus year old bradawl (my father's or possibly grandfather's) with a blunt end.. The manual says "lightly tap with a mallet" .... !! Err, no. Hit violently while supporting the lever end on a block of wood and it will give in..... The not so good news was that the overhaul kit I thought I had from PO turns out to be for the front M/C ! Gutsibits don't have any but on Ebay "Motor Works UK" do so I've ordered one.. To be continued... Thanks again, Adrian Bristol UK Edited by AdrianW - 25 Jul 2025 at 17:44