tristanthompson Posted March 14, 2016 Report Share Posted March 14, 2016 Hey! So I got a pair of water bled magura HS11's which have been sitting in the shed and I guess freezing and re-freezing all winter. Just had a go at bleeding them in the sink and it doesn't seem to be working (they were fine a few months back). Any ideas? Quote Link to comment Share on other sites More sharing options...
jeff costello Posted March 14, 2016 Report Share Posted March 14, 2016 piston stuck? happened to me a few times. took them apart and let them dry out for a few days/weeks - per adams recommendation - put them back together with some lubing and work like a charm again. Quote Link to comment Share on other sites More sharing options...
AdamR28 Posted March 14, 2016 Report Share Posted March 14, 2016 Yep - sounds like what Jeff suggested Quote Link to comment Share on other sites More sharing options...
tristanthompson Posted March 14, 2016 Author Report Share Posted March 14, 2016 Sweet, must be it - they look pretty jammed up. You guys know of any good instructional videos/manuals on how to take these things apart? 1 Quote Link to comment Share on other sites More sharing options...
Ross McArthur Posted March 15, 2016 Report Share Posted March 15, 2016 It's pretty simple. Spanners to unscrew the hose fittings from the lever and slaves. Allen keys to unscrew the bleed bolts from the lever and slaves. Allen key to remove lever blade. The master piston may take some persuading if its stuck. I usually put some mole grips over the nipple (not too tight) and pull it out. Either that or a long thin allen key through the hose or bleed hole and push it out. Oooooor attach an air line and pressurise it out. Same practice as wanking - Don't look directly at it! You cant remove the pistons from the slaves. Sorry about the lack of specifics with allen key and spanner sizes. Cant remember off the top of my head. I usually go with, "No, that doesn't fit. Yup, that one fits" method. Quote Link to comment Share on other sites More sharing options...
jeff costello Posted March 15, 2016 Report Share Posted March 15, 2016 my supershitty pump (for schrader valves) fits almost exactly on the head of the shroud nut. put your finger on the the bleed hole to block it. then blow the piston out. might take some time to move it and might not work if they are stuck really hard. but worth a try before running outand searching for a compressor Quote Link to comment Share on other sites More sharing options...
MartMini Posted March 15, 2016 Report Share Posted March 15, 2016 8 minutes ago, jeff costello said: my supershitty pump (for schrader valves) fits almost exactly on the head of the shroud nut. put your finger on the the bleed hole to block it. then blow the piston out. might take some time to move it and might not work if they are stuck really hard. but worth a try before running outand searching for a compressor i've cut a schrader valve off an old inner tube before, and jammed that in the end of the master cylinder. Its usually a tight fit for the m8 holes. Quote Link to comment Share on other sites More sharing options...
Mikee Posted March 15, 2016 Report Share Posted March 15, 2016 1 hour ago, jeff costello said: put your finger on the the bleed hole to block it. Or just put the bleed screw back in? Much easier when you need higher pressures for a really stubborn piston. 1 Quote Link to comment Share on other sites More sharing options...
Ross McArthur Posted March 15, 2016 Report Share Posted March 15, 2016 Maybe he likes the farting noises. Quote Link to comment Share on other sites More sharing options...
jeff costello Posted March 15, 2016 Report Share Posted March 15, 2016 now that's some progressive thinking in here... finger was enough in my case. i have the new ones with the plastic bleed screws which i always put aside as far away as possible since they break from even looking at them in the wrong way. that's why using it didn't even cross my mind Quote Link to comment Share on other sites More sharing options...
CC12345678910 Posted March 15, 2016 Report Share Posted March 15, 2016 (edited) On 14/03/2016 at 5:04 PM, tristanthompson said: Sweet, must be it - they look pretty jammed up. Any tips? Prerequisites. You are going to need: a track pump with both schreader (car valve) and presta (road bike valve) a spare shoud nut and piece of Magura hose with an olive pre tightened on it. A broken crossover will do, but it's really not the same due to the extra backpressure created by the smaller m6 fitting. Ideally GT85. WD40 is passable. In absoute worst case scenario (been here believe me) a small blow torch on low-medium heat. A good size kitchen hob would be a substitute. METHOD With the brake still all fully assembled; 1) Take the lever pivot bolt out. 2) Wiggle the lever blade out. 3) Move the Tpa ball and rod round 90deg so that they are sat flat against the lever blade, facing away from the pivot. 4) Put the lever blade and pivot bolt back with everything like this. Tighten like normal. 5) Take out the grub screw in the master, the one where the top bleed hose goes. 6) Screw in your piece of hose & shroud nut. Nip it down with an good fitting 8mm spanner (NOT AN ADJUSTABLE!!!) 7) Take the other end of this hose and plug it into your track pump. In mine I have to unscrew the presta side, slide the fitting over the magura hose, wiggle the end into the little olive in the pump and then tighten the fitting up. Whatever you have to do this junction needs to be good & snug or else you're wasting your time. 8) Spray some GT85 down the bore past the piston. Leave to soak for 5mins. Mabye repeat a couple of times 9) Slowly pump some air in. A well lubed working piston should pop out at 30ish PSI. A sticky one at anything up to 80 PSI. If It's being a real bitch, I've been there... See * below. If it has worked; 10) Take the lever blade out again. Find a corner of the garage/wherever you're doing this without a lot of stuff in, preferablely with some form of padding to stop the piston and spring richocheting off god knows where - that sh*t can honestly go miles, so for the love of all things holy point the master away from you . 11) Pump. HARD. Hopefully that should have shot the piston out at a fair ol' lick, and all is well. Find the piston and spring, lube the piston with silicon lube for a racing line piston, for a standard plastic magura one you might want to lightly sand the skirt (the handlebar end) with 400 grit wet and dry, then I recommend Petrolieum Jelly (vaseline) for lube. Or submerge the piston in a cap full of magura oil in either case (safest bet). Reassemble the master and bleed. * I did one with a mate once where it took an indicated 140psi to shift it off the bottom of the bore. Scary as f**k and I thought my pump was going to die... This is where the heat comes in. 9.1) With the system pressurised spray some more GT85 down the bore. It might just pop at this stage. If not 9.2) Grab the bar clamp with some pliers, and give the area if the master around the piston a lick of heat with a medium flame, ideally as little as is needed, and pump some more. 9.3) Repeat?? Then It's being a real C-unit but In 10yrs of trials I've never been defeated yet. As for the rest of the system, When you've got the master working, bucket bleed the brake with the master in a separate container, and mix in a couple of drops of washing up liquid. Seal the brake up, and chuck the water from the buckets. Pump the brake for 5mins. Now bucket bleed the brake again and (in my case anyway) look at all the dislodged sh*te appearing in the waste water bucket. After this hold one slave from moving with your thumb, pump the lever to make the slave fully extend,and pour some 3-in-1 type oil down past there into the gap. Work it it there by pumping the lever, repeat, then swap sides. Maggie service. Done. Edited March 15, 2016 by CC12345678910 Quote Link to comment Share on other sites More sharing options...
tristanthompson Posted March 16, 2016 Author Report Share Posted March 16, 2016 Cheers guys! I'm gonna grab an old pump and go ape shit on these things. Update to follow. 1 Quote Link to comment Share on other sites More sharing options...
Ross McArthur Posted March 16, 2016 Report Share Posted March 16, 2016 12 hours ago, CC12345678910 said: mix in a couple of drops of washing up liquid. Not something ive tried. Will have to give that a go. I recently swapped out the plastic pistons for Racing Line ones. Best decision I've made. No swelling to worry about now Quote Link to comment Share on other sites More sharing options...
jeff costello Posted March 16, 2016 Report Share Posted March 16, 2016 i've had the stuck piston twice now. but each time it was after a prolonged period of inactivity - hadn't ridden the bike for 2-3 months. i never had it happen when in regular use. ( iirc occasional freezing of the brake was involved too each time) Quote Link to comment Share on other sites More sharing options...
CC12345678910 Posted March 19, 2016 Report Share Posted March 19, 2016 On 16/03/2016 at 10:32 AM, Ross McArthur said: Not something ive tried. Will have to give that a go. Arrr trade secret... Nah honestly, It's something that just came to me one time when I got some brakes that were slow from having a filthy old factory oil bleeds sat in them - I 'fairy bled' (what I've christened it) one and visible lumps/chunks of black grot poured out of the slaves. When I pulled my hand out of the waste bucket after tighening the bleed bolt I had an oil slick tide mark on my forearm . You'll find that the brake will be slow returning after you have flushed it though, as (I summise) you've also washed away any lube, hence the instructions to re-lube the slaves. IME you have to be ready to break the master apart again to redo any lube you put around the piston, but it's worth it - that brake has seen 5 different bikes now, and it's had nothing more than a couple of top up water bleeds & some wilko 3in1 on the slaves when they get dry. Quote Link to comment Share on other sites More sharing options...
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