New martas - squealing, no power

Have you checked that the rotor is centered perfectly in the caliper? Could use a tab facing if you have IS mounts. Also, is the rotor perfectly true?

All magura brakes reward you if your install is perfect. Generally speaking, you can't just bolt them on and expect them to shine.

Since your lever pull is similar both front and rear, I would look at installation issues. Also, if you find issue with the install, then lightly scuff up your pads with so sandpaper and clean your rotors with alcohol before a new break in.

Louis

The pad could also just not be broken in, not likely though.

Are both pistons extending and retracting the same?

I did not have the frame or the fork prepared with the tool. I took great care to install them, and the front set up pretty quickly. It was at least parallel to the disc. I got it centered after about an hour of work. It spins without drag. the rear was much more time consuming, and required some tapered shims made up from some 0.2 mm sheet metal. I know the tool would have negated this, but I was anxious to get them on. I finally got them both centered, and spinning freely. the front lever did compress a little more than the rear, and did not feel quite as hard, out of the box.
I was amazed that my full grip strength could not lock up the front tire. I was careful not to touch the disc after I cleaned it with alcohol. I did not sand the pads.

Severum said:

The pad could also just not be broken in, not likely though.

Are both pistons extending and retracting the same?

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I will check and get back. I rode for about an hour and a half, so got lots of stopping. but I did not do the 15 stops from 30 kmh beforehand as they recommeded.

kindacreeky said:

I will check and get back. I rode for about an hour and a half, so got lots of stopping. but I did not do the 15 stops from 30 kmh beforehand as they recommeded.

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The pads both appear to be compressing and retracting together. The pads do not touch the disc at all when I spin the tire. The lever definitely does have a little sponginess to it, compared to the rear.

Is the rotor dead center in the caliper? Do the pads travel an equal distance to the rotor? you may have to do a micro adjust.

Severum said:

Is the rotor dead center in the caliper? Do the pads travel an equal distance to the rotor? you may have to do a micro adjust.

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As near as my eye can tell, it is dead center, and appears to be parallel. Can a little bit of "off-center" cause my symptoms? Would not the first thing to try be to remove the pads, sand lightly, and clean the rotor again? Another question: could a little air cause these symptoms, or is that wrong? this is my first set of hydraulic discs.

nwmtb said:

this really sounds to me like the disc tabs need milled. Magura brakes are highly dependent on a square surface. Check this out too while you're at it.

good luck, Chad

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I don't understand. The tabs just hang out of the functional part of the disc. I have never heard of this, and I have read quite a few of these posts. Is this something I can do, or do I need new pads?

kindacreeky said:

got my new Marta SL's installed this weekend, and got to ride today. The Rear feels great, and will easily lock up the tire. the front does not feel too differently in the lever pull, but will not lock up front no matter how hard I pull. Also, when pressure gets pretty high on the pads, it squeals real high pitched and loud. I figured it needs bleeding. Is this right? don't have the bleed kit yet, but it should be here tomorrow. I am psyched about these new brakes, and can't wait to get them dialed in. --Bob in Nashville

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this really sounds to me like the disc tabs need milled. Magura brakes are highly dependent on a square surface. Check this out too while you're at it.

good luck, Chad

Well, that bleed might help. Be sure to get those pads a mile away while you are doing the bleed. Clean any excess oil well.

nwmtb said:

this really sounds to me like the disc tabs need milled. Magura brakes are highly dependent on a square surface. Check this out too while you're at it.

good luck, Chad

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I agree.

Severum said:

Well, that bleed might help. Be sure to get those pads a mile away while you are doing the bleed. Clean any excess oil well.

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I will bleed them tomorrow night, and then post results. Thanks so much for the help (so far).

Severum said:

I agree.

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I understand. Will get tabs milled too, if bleeding does not help.

It sounds like contaminated pads to me

I agree that instalation is key but I have run my Martas way off center once when I was in a hurry to get out on the trail and they never had the lack of power you describe. Before you go through all the trouble to get your tabs faced I would just take the pads out of the rear brake that works well and put them in the front and test it. If that dosn't work and you decide to face the tabs be sure to get it done by someone who not only has the right tool but takes good care of their tools. I had my frame seriously messed up by a facing tool that had been droped or misstreated.

You/we might be a bit confused on this...

kindacreeky said:

I don't understand. The tabs just hang out of the functional part of the disc. I have never heard of this, and I have read quite a few of these posts. Is this something I can do, or do I need new pads?

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I should know what the hell I'm talking about before I post!

Johnny Hair Boy said:

I agree that instalation is key but I have run my Martas way off center once when I was in a hurry to get out on the trail and they never had the lack of power you describe. Before you go through all the trouble to get your tabs faced I would just take the pads out of the rear brake that works well and put them in the front and test it. If that dosn't work and you decide to face the tabs be sure to get it done by someone who not only has the right tool but takes good care of their tools. I had my frame seriously messed up by a facing tool that had been droped or misstreated.

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Thanks. That sounds like a logical first step. If they are contaminated, I can't imagine how. I cleaned the discs three times while I was setting them up, just to make sure did not get contaminated. Since this is holiday weekend, will not take my bike in till next week, so have the weeknd to experiment with all these ideas. Will report back on this thread. Thanks again.

kindacreeky said:

Thanks. That sounds like a logical first step. If they are contaminated, I can't imagine how. I cleaned the discs three times while I was setting them up, just to make sure did not get contaminated. Since this is holiday weekend, will not take my bike in till next week, so have the weeknd to experiment with all these ideas. Will report back on this thread. Thanks again.

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One more thing, is there one type or brand of tool that is better? I have seen the Magura Tool, the Gnanomat?? in the shop book. Should I look for a shop that has that tool?

The joy of Martas

I had the same problem for almost a year before having to send my rear Marta back to Magura. They sent me a new one but by that time I was so soured on the product I sold the set. This board kept telling me it was a set up problem but it wasn't. They were a complete pain in the arse from the get go. Like a trip to the dentist, like a rainy day in July, like a major case of constipation, etc. You get the point.

My point is this: if you continue to have problems, give Magura a call. Their customer service is awesome! They will guide you. I had a leaky, screwed up rear brand new.

Jaybo

[Well, I got to work on them tonight, and I can't believe I did not notice, but the disc has oil all over it. I guess the caliper blew a seal?? do I have to send thse to Magura to fix?