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PostPosted: Wed May 15, 2013 12:31 pm 
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I get really uneven pad wear on the rear calliper. It seems as though both pistons are moving so wondering why this might happen?
Anyone shed any light on it?

I have trawled the magura 'community' site but it leaves me with an all engulfing sense of angst so i thought I'd try here.

Thanks

Rich


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PostPosted: Wed May 15, 2013 2:14 pm 
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You might have a bit of a lazy piston, which would cause one pad to hit the disc before the other, and then that same piston would retract slower, so the same pad would drag on the disc a little bit more once the brakes are released.

It might be worth lubricating the piston body to see if that makes a difference. It used to be a common occurrence with the first generation Hope Mono Mini/M4/M6s..


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PostPosted: Wed May 15, 2013 5:07 pm 
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Thanks for that. Would you use a bit of brake fluid or an oily lube?


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PostPosted: Thu May 16, 2013 7:38 am 
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As it's Magura brakes we're talking about they use mineral oil, not DOT brake fluid.
But you probably won't need to do this anyway - have a look at this video which explains it better than I could. If you have IS mount brakes then the initial caliper centering will have to be achieved by shimming, between the caliper and the mount, rather than the method shown for post mount brakes.
After that, the pad centering method works just as well with Martas as with Hopes.

Do you have any pad drag at present or are both pads clear of the disc when retracted and do the pads wear "square", or more at the front or back?

You could also try (in addition to centering) cycling the pistons through their full travel a few times - remove the caliper from the frame and take out the pads. Push both pistons as far back into the caliper as they will go and then very slowly operate the brake lever to push them back out again, all the while checking that both are moving the same amount. If one moves more than the other then hold that one back to force the slow one to move out.

Do not pump the pistons out any further than a 6mm spacer between them will allow(the thick hose cutting guide end of the yellow transport spacer is ideal) and make sure that both pistons move about evenly as otherwise, if one sticks in the retracted position, it is possible to push the other out too far, even with a 6mm spacer in place.


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PostPosted: Thu May 16, 2013 9:39 am 
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Brillian Andy, thanks. I'll check it out properly later.

As you may notice from another post, a more serious magura issue has developed...


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PostPosted: Thu May 16, 2013 8:19 pm 
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Andy R wrote:
As it's Magura brakes we're talking about they use mineral oil, not DOT brake fluid.



indeed - mineral oil - same as what is used in shimano brakes - which is cheaper.


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PostPosted: Fri May 24, 2013 11:22 pm 
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Pushed the pistons in and out and soaked the rear calliper in mineral oil and then bled the rear brake and now working perfectly again. Thanks for the advice.

New pads in yesterday so I'll have to see how they wear.


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