I had to remove the brake handle from my HS33 maguras so I could remove and lube that little plastic spindle, used for adjusting the brake. It had become “fused” and would not turn, so after removing the handle I was able to get it turning freely again. But after putting the handle back on, it now seems sluggish and lacks the same stopping power. It seems that air may have gotten into the lines. So how can I bleed the system, and, if necessary, add more brake line (mineral oil?) fluid? 
Get one of these.
That comes with some magura fluid, a lot of trials bikers use water in their lines and really like it. They say it gives it a more snappy feel but it wears the seals down faster.
Thanks that looks good, but I have NO idea of how to do that, although I assume there’s instructions, I’d rather let a tech at the LBS do it. Do you think the average LBS knows how to bleed and add fluid? Maybe an LBS that specializes in mountain bikes?
It depends on the bike shop. A lot of bike shops I would not let near my hydrolic brakes.
I heard that the standard magura “fluid” is regular old Mineral oil…is that true? Because maybe I should just drain the lines and refill it with new fresh mineral oil.
This site seems to be the best source of magura information:
http://www.execulink.com/~dtierney/wmc/Magura/
and here is how to bleed magura rim brakes:
http://www.execulink.com/~dtierney/wmc/Magura/bleeding_tips.htm
"Cooking Oil will get rancid and changes viscosity. Mineral Oil from the Supermarket is also not a good substitute. You never know what viscosity that stuff has. Mostly a weight of 30 is sold but again, nobody knows for sure, because of the different measurements in viscosity. For emergency work in the middle of nowhere cooking oil, or mineral oil will work…so does water but it all really needs to be flushed later.
Probably the best emergency alternative is Sewing machine oil. It is available even in so-called third world countries.
NEVER use DOT (Car/Motorcycle) Brake fluid. It will destroy the seals. DOT brake fluid will attract water which makes the boiling point go down quick. (That’s why the folks with “other” disc brakes have to change the stuff every year or two). And it is environmental a disaster. Not to mention that it will eat paint for breakfast and the real damage it can do to Carbon and other frame materials is widely unknown)"
"Hydraulic oil
Magura Oil, which is filled into the brakes in Germany is greenish - Shell Naturelle. Unfortunately Shell USA doesn’t sell (import) that same stuff. Shell USA says that this (environmental friendly) oil is too expensive for the American market. Magura USA could get it in a special load (a boat load?) but it probably would last to the year 3000.
Magura USA searched high and low and ended up with Finish Line Shock Oil No 5, which is actually a mineral based synthetic oil and is of a reddish colour. Finish line shock oil is also environmental friendly and if you can trust the folks at Shell, it will mix with the original Shell stuff. It also has a better lubrication value than even the original German Shell.
So…all brakes are filled in Germany with Shell Naturelle. All Oil in the bleedkits and separate oil bottles available from Magura USA is Finish Line No. 5 Shock Oil.
The viscosity or weight is measured in different ways in Europe and in the USA (figures!) but the original Shell Stuff is about 8 weight. The Finish Line again is 5. ( The smaller the number the thinner it is)
In case of extreme low temps, Finish Line No 2.5 weight is a temporarily accepted fix. It will make the brake levers return faster. Also 2.5 weight is Thorsten’s personal choice for the rear Louise Disc brake."
umm do you work for magora??? don’t be a sissy use mineral oil its cheaper and was easer to get.
magora hs style breaks are actually fairly rare on mountain bikes and they are deferent to bleed than normal hydraulic disk breaks. try to find a shop that deals with trials bikes if you can
Ok thanks!
Umm, no I dont work for magora. Nor do I work for Magura. That information came straight from a magura enthusiast site as far as I know.
yeah i know i rember reeding it and its bs minreal oil is fine.i run it in 2 of my unicycle breaks and the maguras on my trials bike
Yeah, Im sure somebody told me that you could do that before, but im not sure who it was and how reliable they are as a source.
Im still looking to buy maguras for my coker and my muni at this stage so have no experience using any.
Magura rim brakes are fussy enough as it is. Using some random mineral oil from the drug store would be an exercise in trial and error. If the mineral oil is too viscous the brake pads will retract more slowly and not in sync. When you squeeze the lever one brake pad will move in well before the other one. The brake cylinders are in series, not parallel, so one ends up reacting first before the other. With thicker (more viscous) fluid the out of sync behavior is more pronounced.
It is easy and cheap enough to get the Finish Line Shock Oil. It’s a known fluid. There is no need to MacGyver it with some random mineral oil.
Terry,
Here is a link that I found very helpful. John childs goes into more details on Magura stuff. Read the entire thread. http://www.unicyclist.com/forums/showthread.php?t=52628
Cheers.
most bike shops should have at least one mechanic who can work on your brakes. the best way to find out is to call a few and ask. also ask for a rough estimate. problem solved. at least if you don’t want to do it yourself.
please let your shop do the first time. have them walk you through it, its worth the 20-40$. i have seen so many joe blow home mechanics mess up their brakes its not worth it.
Yes, JC is The Man on Magura bleeding and functionality. And let’s not forget that he makes house calls if the price is right and your house is in the right place. After a JC lesson last year, I finally had my first “solo attempt” at bleeding my Magura last month. As I went through the process, I found myself talking to myself in JC’s specific, instructive voice. I resisted the temptation to call myself an idiot. The procedure went just fine.
Thanks JC!
Hey Terry,
don’t be afraid of bleeding a Magura HS33. It’s not really difficult if you got the bleeding kit. I’ve done it a couple of times just following the instructions of the manual.
The only advice I can give you is to get a mate for a second pair of hands. It’s pretty difficult to catch all the oil at the brake lever and pushing the syringe at the brake itself at the same time.
I suppose everyone could do it, it is nothing compared to bleed a disc brake and that is doable as well with a little effort.
Terry,
It may be possable that your tps is dialed out a little more now that you have messed with it. Maybe you just need to dial it back in?
How to tell that you have air in the lines; squeeze the lever, pads should move at exact time the lever moves, and the pads should retract just as quickly as the lever. The lever will feel a little more squishy after the brakes have fully contacted the rim, and you will have less power.
water ftw! My friend has run water in the hs33 on his trials bike for years, no blown seals yet. On the other hand, the hs33 on the front of my bike has only ever had a factory bleed, and has developed a small leak at the slaves.
The boiling point is moot, you’re not going to boil the fluid in your brakes. Water does give a quicker action at the lever, I’m not sure that would make much difference on a muni since you’re just using the brake to drag on the rim vs. the quick lock/unlock that is used in bike trials.