Bleeding Magura HS11 rim brakes - epic kit

[Blue Hills]

Anyone used this for bleeding Magura HS11s?


http://www.epicbleedsolutions.com/products/bleed-kits/magura/rim/complete-kit/

Mine are 2002 brakes - this is the first time I will have bled them.

Specific questions:

Is it difficult?

Are the instructions that come with the kit good?

How much oil are you likely to need? ie: Is the amount that comes with the kit sufficient, particularly bearing in mind that I have never bled mine? (I'm wondering whether to buy an extra bottle).

Anything in particular that I should bear in mind given the age of my brakes - I think they differ in some respects from the latest HS11s which maybe the instructions are more specifically aimed at.

The brakes haven't worked properly for a while (not complaining) but I fancy transferring them over to a new frame.

Thanks in lubed anticipation.

 

[Yellow Saddle]

Instructions are fine, bits and bobs that come with the kit are fine, oil is fine. You will have enough oil in there, no problem. The brakes contain surprisingly little oil, so 50ml will fill both sides with ease, even if you replace all the oil in the system.

However. Why do you want to bleed your brakes? What are the symptoms of the problem. Bleeding is not the panacea for all problems brake related and you may just end up with exactly the same problem on new oil.

 

[Tim Hall]

The Yellow one has it pretty much covered. I've had Magura rim brakes about 16 years and bled them once, and then it was only the front one, as that was the hose that got cut when I flung the bike down the road. Bottom line is, if it ain't broke, don't fix it until it is.

 

[Crackle]

You don't need much oil and be careful not to spill any oil on your pads and discs.

 

[Blue Hills]

However. Why do you want to bleed your brakes? What are the symptoms of the problem. Bleeding is not the panacea for all problems brake related and you may just end up with exactly the same problem l.

Many thanks for your advice and positive words on the kit yellowsaddle.

Symptoms. Levers come a bit too close to the bars before full force is applied. I have adjusted the screw in the levers pretty much as far as it will go. On one of the brakes, the pad doesn't always pull back from the rim properly when the brake lever is released.
Non techie me associates this with a loss of pressure somewhere in the system and I stress that the brake were used continuously for a good ten years.
I am not aware of any leaks.
Interested in your reply as you seem to know your stuff.

 

[Yellow Saddle]

Many thanks for your advice and positive words on the kit yellowsaddle.

Symptoms. Levers come a bit too close to the bars before full force is applied. I have adjusted the screw in the levers pretty much as far as it will go. On one of the brakes, the pad doesn't always pull back from the rim properly when the brake lever is released.
Non techie me associates this with a loss of pressure somewhere in the system and I stress that the brake were used continuously for a good ten years.
I am not aware of any leaks.
Interested in your reply as you seem to know your stuff.

If you pump that lever, does it "come up"? Air in the system can be temporarily fixed by pumping. That's a sure sign of air but then you still have the issue of how the air got in the system in the first place. You sure there are no leaks somewhere which will be seen as oily residue?

Secondly, the pad not pulling back is not going to be fixed by bleeding but by cleaning the pistons. This is best done with the pads out and the pistons pumped out as far as you can safely pump them without them popping out. In other words, tread carefully. Try and hold one piston in with a tool of sorts and only pump one out at a time, to a point just beyond the dirt line and then clean it off with some soapy water and finish it with a Q-tip soaked in some of your blue oil. I'm sure there are plenty of YouTube videos on the topic.

 

[Blue Hills]

Thanks for the reply yellowsaddle.

Yes, if I pump the lever that does provide a temporary solution.

So by your analysis that does mean air.

You seem to imply that this means that my system (hoses plus bits) has some sort of basic problem that won't be fixed by bleeding.

But I had the idea in my (I stress non techie) head that this is what bleeding means (a la bleeding a radiator/heating system) and the very reason for folk doing the bleeding process. Is this not true? If it isn't true, why do folk bleed their systems at all?

Also, even with a basically intact system isn't it to be expected that after so long SOME air (and it assume that due to the system's low capacity not much air is needed to upset things) will get into the system. Isn't this a fair assumption?

On the sticking piston, yes I have a few times held one pad still while pumping and this does produce a temporary solution but after a while the problem returns.

Could this sticking pad be caused by a combination of a bit of dirt and air in the system - ie - if there is air the hydraulics aren't going to be pushing the mechanical components with sufficient force?

I am assuming that this sticking of the pad terminal isn't terminal?

Many thanks for your help with this - caution - may be back with other queries after this issue is sorted as my intention is to transfer the system to another bike as an alternative to fitting V brakes. I intend to use the bike for day rides.

Thanks again.

Look forward to your reply.

 

[Yellow Saddle]

Thanks for the reply yellowsaddle.

Yes, if I pump the lever that does provide a temporary solution.

So by your analysis that does mean air.

You seem to imply that this means that my system (hoses plus bits) has some sort of basic problem that won't be fixed by bleeding.

But I had the idea in my (I stress non techie) head that this is what bleeding means (a la bleeding a radiator/heating system) and the very reason for folk doing the bleeding process. Is this not true? If it isn't true, why do folk bleed their systems at all?

Also, even with a basically intact system isn't it to be expected that after so long SOME air (and it assume that due to the system's low capacity not much air is needed to upset things) will get into the system. Isn't this a fair assumption?

On the sticking piston, yes I have a few times held one pad still while pumping and this does produce a temporary solution but after a while the problem returns.

Could this sticking pad be caused by a combination of a bit of dirt and air in the system - ie - if there is air the hydraulics aren't going to be pushing the mechanical components with sufficient force?

I am assuming that this sticking of the pad terminal isn't terminal?

Many thanks for your help with this - caution - may be back with other queries after this issue is sorted as my intention is to transfer the system to another bike as an alternative to fitting V brakes. I intend to use the bike for day rides.

Thanks again.

Look forward to your reply.

If your system pumps up like you say, then it needs bleeding. Air can get trapped in the system under some unlikely circumstances other than through a leak. For instance, if the bike was on its side or upside down and someone played with the levers. Just inverting the bike will by itself not introduce air in the system. In your case I'd say you have the right symptoms for the bleeding treatment. Bleem 'em.

Sticky pads. Remove the pads so that you can see the ends of the pistons. Restrain one piston using a cone spanner or flat instrument (knide blade etc) laid flat on the piston and held in place with your one hand. Now pump the lever and allow the remaining piston to come out a little bit. Once you can see the clean bit exposed, stop pumping. There is a danger of them popping out. Now clean the dirty ridge using ear buds, soapy water or alcohol. Yes, Vodka will work but beer not.

Drip a little oil on an earbud and smear right round the clean piston. Repeat the procedure but now on the other one.

Those are fantastic brakes, service them and keep them.

 

[Blue Hills]

Thanks for the encouraging news yellow. I've never been sure about the turning upside down thing. I have heard that it can cause problems and also that this is a myth.

The bike they are currently fitted to has very regularly turned upside down for various bits of maintenance, removing wheels etc. And yes, i may very well have operated the brake levers when it was upside down to check various things. Is this actually a problem?

 

[Yellow Saddle]

Thanks for the encouraging news yellow. I've never been sure about the turning upside down thing. I have heard that it can cause problems and also that this is a myth.

The bike they are currently fitted to has very regularly turned upside down for various bits of maintenance, removing wheels etc. And yes, i may very well have operated the brake levers when it was upside down to check various things. Is this actually a problem?

Yes, it is a problem - you have to bleed each time it happens.

 

[Blue Hills]

So it's not turning the bike upside down as such but turning over and operating the levers?

Am intrigued/puzzled as to how this gets air into the system.

 

[Yellow Saddle]

So it's not turning the bike upside down as such but turning over and operating the levers?

Am intrigued/puzzled as to how this gets air into the system.

Yes, that's the problem.

Most brakes other than Avid Elixir (and perhaps new Avid models which I'm unfamiliar with) have a little reservoir of brake fluid at the brake lever. This is a little bowl that gravity feeds fluid to the system as it pumps fluid to let the pistons move. It also feeds fluid as the pads wear and the pistons protrude further and further. At the bottom of the reservoir is a hole that leads to the master cylinder. If the bike is inverted, the reservoir's open space is now directly over the hole, no longer covering it with fluid. This is not a problem in that it causes the system to drain because the hole is small and capillary action keeps the fluid in there. However, if the lever is now activated it will cause movement in the fluid and intrusion of a bubble. You can imagine a length of small diameter plastic hose like fish tank hose or similar. When it is small enough and filled with water you can't just drain it, you have to shake it. The force that keeps the water inside is capillary action.

Systems like Shimano have a rubber bellows that sits on top of the fluid in the reservoir and in theory eliminates the air above the fluid. In theory only because we don't bleed that gap, we only plonk the bellows on top and hope all air is expelled.

 

[psmiffy]

I thought the Magura was a totally closed system - I used a couple of sets of HS33 for over 10years and never touched them apart from changing the pads - despite them having been inverted on more occasions than I could count and being subjected to a couple of dozen flights

 

[Yellow Saddle]

Totally closed is a vague term. I imagine it simply means the fluid can't leak out. Internally the system needs space for the fluid to transfer from one chamber to another and that can only be provided by an air chamber that can accommodate rising and lowering fluid levels. Inversion per se is not a problem. Read what I wrote about the conditions required for air to enter the system.

 

[psmiffy]

Ive never really worked out exactly how they work - but I always thought they were different to conventional bicycle hydraulic systems in that there is no reservoir - no need to port the air? In fact if bled properly no air in the system?