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Magura Master Seized?!


brettboone

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Perhaps you can help me.

I came to bleed my HS33's for the 1st time the other day (i've owned them for 5 years but they have been dormant for 3) as there was play in the lever before the lever arm engaged the master piston regardless of the position of the TPA. I bled them according the the magura manual but the problem was not solved, in fact it is worse. Even with the feed valve open at the slave, the master piston would not return to its open-most position so I took the master assembly apart. It is extremely difficult to move the piston in the cylinder which I suppose is the reason that the spring cannot do its job.Do you think that this has been caused by the TPA keeping the piston in a halfway position in the cylinder for so long in all temperatures whilst its been sat dormant? I have tried to clean the cylinder with wire wool but this has had no effect.Is the spring the only mechanism in the system that causes the slave to recoil from the rim?

Please help me as I'm very confused and all I want to do is get back on my bike...I've missed her so badly!

Thanks alot

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I tried that but no amount of pressure on the syringe would budge the blighter. All that happened was that the tube popped off and squirted at my dog.It is REALLY hard to move,I had to hammer at it through the bleed whole with a thin drill bit in order to make it move.I understand it needs to be tight for a good seal but this is ridiculous!

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Lengthy post here so sit back and read!

Take the brake off the bike so it's in hand.

Spray some lube, GT85, WD40 any realse lube on the slave pistons and pump the leaver.

Then do the same at the master piston.

Strip the unit down.

Run a sink full of hot water with fair in there!

Put it in and leave for ten mins.

Take a tooth brush, old one unless you want black teeth.

Scrub the unit clean, espichaly around the slave pistons

If you can remove the master piston, use a spoke to push it out, give that a good clean and in the barrle too.

Then run it all under some hot water to wash dirt off and fair etc!

It should now be nice and clean, no grit, dirt, grease, dust etc

You can run hot water through the the hose to clean that out too.

Assemble the unit again.

Now boilt the ketle, mines milk and 3 sugars!

Fil a cup with the boiling hot water, be careful now.

Fill a syringe up.

Wind the tpa all the way off.

Bleed the unit in the sink from the slave!

The hot water will clean the system intenaly, hot water will disolve most stuff.

Do this a least 3/4 times it's clear.

Then bleed the system with water, oil etc what ever you want.

I bleed mine with hot water, cleans them out and nicer bleed i find!

If you still have problems i'll be happy to have a fondel with the unit.

I built Josh grenny's brake, his slaves were shagged up, did the above snorted!

I know Magura's inside out!

Pete

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Thanks,ill try that in a bit and let you know how it goes.

Seriously though 3 sugars?!...Whether you use your toothbrush for brake-cleaning or not I fear you may have black teeth to come

I'm diabetic and my SL is dropping and i'm busy cutting pads so can't be bothered to move! I normal have 1 1/2 in my tea.

Let me know how it goes!

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I'm diabetic and my SL is dropping and i'm busy cutting pads so can't be bothered to move! I normal have 1 1/2 in my tea.

Let me know how it goes!

You do realise if you go hypo, you'll be stuffed.

If you are diabetic i'd go get some sugar or sweets.

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You do realise if you go hypo, you'll be stuffed.

If you are diabetic i'd go get some sugar or sweets.

Yep, last one was a month ago or so! My Son knows what to do as he is diabetic too. My logers know also. I found a mars bar in my laptop bag so it did the job till i moved!

Pete

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I had a go at what you suggested. Everthing is now much cleaner/better tasting but i'm afraid the problem persists.With hot water in the system and everything sealed the master piston did return some of the way up the cylinder but not all the way.The lever is still slack with the tpa wound all the way off.I assume that in a fully functioning lever this isnt the case and the piston returns to the openmost position when newly bled?!

What do I try next? I may polish the barrel with a polishy attachment on a drill to lessen the resistance on the piston. I really dont want to fork out £70 for 2 new levers.

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Did you remove the master piston in the leaver and check the o ring? I say it's worn ad your barrel is scroed. Go ahead with the polishing and checking that O ring. Might be worth to use some high grit paper, 1000+ emery to take that barlle down a bit.

My Maguras are going for a full strip, mod and service tormrow and i'll be doing 400, 600, 800, 1000, 1200, 1500, 2000 grit on a stick back and forth as if the piston was moving then a polish then a hot water clean!

Will make them work a lot better!

Glad my advice was of use!

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