Shimano Saint lever overhaul - sticky lever piston/plunger

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Shimano Saint lever overhaul - sticky lever piston/plunger
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Posted: Jun 14, 2021 at 4:05 Quote
I'm trying to find instructions on how to strip down Saint BR-M820-B levers. I've found info on XT levers, but the internals are a little different, the Saints dont have the plastic guide strips. I've removed the lever and plunger, but cant get past the plastic cap (part of the free stroke adjustment) to get to the piston and spring which is where my brake's problem seems to be. I've tried using a 2mm allen key to push from the hose end, but nothing budges even slightly.

Has anyone completely stripped down and cleaned a Saint lever?

I suspect I have done something to damage the seals, the spring isnt pushing the piston back out and the lever is 'floppy'. The issue also seems to have blocked off the bleed hole, as using a funnel to try and get more oil in there does nothing at all (nor can I force oil through from the calliper end).

I think I'm looking at new levers, I've just tested the callipers with an old XT lever and fortunately it looks like I can replace the Saint levers with XT or SLX which are more easily available.

Thanks

Posted: Jun 14, 2021 at 22:16 Quote
AgentDagnamit wrote:
I'm trying to find instructions on how to strip down Saint BR-M820-B levers. I've found info on XT levers, but the internals are a little different, the Saints dont have the plastic guide strips. I've removed the lever and plunger, but cant get past the plastic cap (part of the free stroke adjustment) to get to the piston and spring which is where my brake's problem seems to be. I've tried using a 2mm allen key to push from the hose end, but nothing budges even slightly.

Has anyone completely stripped down and cleaned a Saint lever?

I suspect I have done something to damage the seals, the spring isnt pushing the piston back out and the lever is 'floppy'. The issue also seems to have blocked off the bleed hole, as using a funnel to try and get more oil in there does nothing at all (nor can I force oil through from the calliper end).

I think I'm looking at new levers, I've just tested the callipers with an old XT lever and fortunately it looks like I can replace the Saint levers with XT or SLX which are more easily available.

Thanks
it sounds like the rubber seals on the piston is swollen due to oil contamination,I’ve had it a few times on shimano levers.Only thing you could try is boil the pistons to try and remove the contamination and then lightly sand the piston seals and try and install.I’ve tried this after reading it works,but has never worked for me personally.It’s always been a new lever unfortunately to resolve it.I tend to bleed my brakes more routinely now to avoid this happening.Hope this helps

Posted: Jun 15, 2021 at 1:29 Quote
jase111171 wrote:
AgentDagnamit wrote:
I'm trying to find instructions on how to strip down Saint BR-M820-B levers. I've found info on XT levers, but the internals are a little different, the Saints dont have the plastic guide strips. I've removed the lever and plunger, but cant get past the plastic cap (part of the free stroke adjustment) to get to the piston and spring which is where my brake's problem seems to be. I've tried using a 2mm allen key to push from the hose end, but nothing budges even slightly.

Has anyone completely stripped down and cleaned a Saint lever?

I suspect I have done something to damage the seals, the spring isnt pushing the piston back out and the lever is 'floppy'. The issue also seems to have blocked off the bleed hole, as using a funnel to try and get more oil in there does nothing at all (nor can I force oil through from the calliper end).

I think I'm looking at new levers, I've just tested the callipers with an old XT lever and fortunately it looks like I can replace the Saint levers with XT or SLX which are more easily available.

Thanks
it sounds like the rubber seals on the piston is swollen due to oil contamination,I’ve had it a few times on shimano levers.Only thing you could try is boil the pistons to try and remove the contamination and then lightly sand the piston seals and try and install.I’ve tried this after reading it works,but has never worked for me personally.It’s always been a new lever unfortunately to resolve it.I tend to bleed my brakes more routinely now to avoid this happening.Hope this helps

https://www.pinkbike.com/forum/listcomments/?threadid=230030

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