Magura experts - sticky slave cylinder?

[foz]

reassembling my magura HS33, and the master cylinder seems very sticky. It was working fine before I took it all apart :facepalm: But now I've put it back together, the piston seems very sticky inside the cylinder. It's the same cyclinder, spring and piston as before, so I don't know why it's not as smooth now as it was before. I've lubed the piston with a couple of drops of brake oil, but it seems to stick. Is it possible to overtighten the pivot screw that holds the lever blade to the body? or could the O ring have dried out and/or expanded while it's all been apart?

I've been googling and come up with nothing, except for someone else who had the same problem and solved it by filing down the piston :shock:

Any help would be greatly appreciated!

 

[itscervo]

Re: Magura experts - sticky master cylinder?

Yes it is possible to over tighten the pivot bolt, why did you take it apart :?: .

 

[bm0p700f]

Re: Magura experts - sticky master cylinder?

Or the o ring has come out of its grove and dragging a bit. It's the kind of problem that you will just have to check everything and maybe take it apart again and reassemble. Annoying I know.

 

[My_Teenage_Self]

Re: Magura experts - sticky master cylinder?

When you say brake oil... you do mean a mineral oil...?

 

[foz]

Re: Magura experts - sticky master cylinder?

Sorted, thanks! I'd overtightened the pivot bolt slightly :facepalm:

I took it all apart because it was light blue and the paint wasn't in the best shape ever. The body is now matt black, as are the slave cylinders and mounts. I also swapped the silver lever blade for a black one, so now it matches the shimano disc lever on the other side quite well

And yes, I used a couple of drops of shimano mineral oil. My LBS is so good he sold me 50ml from his 1L can for only a couple of quid

Now I just need to connect lever, hose and slaves, and fill with oil. First I need some clear pastic tubing to finish my own bleed kit - hardware shop tomorrow morning for that!

 

[dyna-ti]

Re: Magura experts - sticky master cylinder?

You cannot make an omelette without first cracking the eggs

 

[foz]

Changed the title of the thread... so I finally got everything together, bled the brake, and it's working nicely, except that one of the slave cylinders (the one at the end of the crossover, not the one where they hose from the lever attaches) seems to not push the piston/pad out as far as the other one, and takes longer for the pad to go back in again.

I guess it's sticking slightly, but is there anything else it could be? I've sprayed some lubs on to the piston behind the pad and pumped the lever several times, but it doesn't seem to have got any better. I'm not in need of an urgent fix, as they seem to be working, just not perfectly. I won't be happy until it's perfect though :facepalm:

I have other slave pistons that I can use, I just don't fancy doing it right now since I just got everything fitted as it should be and bled the whole thing...

 

[hamster]

I'd ride it - a bit more movement may loosen it up further. The slaves are not serviceable, so if it is intolerable then you have to swap it out. Usually on mine I find one slave is slightly looser than the other - it's no problem unless the slave sticks (unusual) or doesn't release cleanly. The force applied by the slaves will be the same.

 

[foz]

I haven't ridden the bike yet (haven't ridden a bike since august :facepalm: ), but playing with the brakes a bit if I hold down the left hand slave (where the hose from the lever enters), the right hand one will push the piston out all the way no trouble at all, and it appears to go in again quite easily when the lever is released. When I don't hold the LHS piston, the RHS doesn't move as far. Might this be a sign of air in the system somewhere? Or is it just that both slaves need to be more or less perfectly matched in stickiness and strength of the return springs? Do I need to start swapping out slaves one my one until I find a pair that are matched?

 

[FluffyChicken]

Re:

What do you mean by not serviceable, you can pull the canti's holder piston out and clean and lube it all up.

Mine where perfect after that, but a bit of dust and dirt and they are back to being lazy. Damn annoying and I wish there was some sort if balancing since when it is muddy or sloht dirt on the rim you get scrapping on one side as you cannot pull the breaks to the rim and feather the brakes like you do with canti's.
It's the biggest flaw with them in my opinion. Other than being heavy.