Shimano bleed proce...
 

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Shimano bleed procedure

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I have a set of M6000 brakes. The front one has zero power - when moving I can pull the lever all the way to the bar and while it slows me, it does so slowly and with a lot of squealing.

I’ve followed every bleed procedure I can find and the result is always the same.

I’ve tried new pads and disc and it’s the same.

I’ve never had problems bleeding brakes before. Am I doing something wrong? Or do I need new brakes?

something that strikes me as odd - if I remove the caliber and master cylinder bleed screws, the fluid drips out of the caliber super slowly. Makes me think maybe there is an air lock or something somewhere as I’d expect the fluid to pour out pretty fast, no?


 
Posted : 15/09/2023 5:52 am
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Sounds like a possible diaphragm/piston seal failure in the lever or a leak at the calliper end. Any evidence of fluid on the pads/disc. If you put kitchen towel through the calliper with the pads out does it come out dry?


 
Posted : 15/09/2023 6:04 am
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Squealing could be possible contamination. I've found it's unusual to have trouble bleeding air from the front brake, as with such a straight-up hose route, there's not usually anywhere to trap an air pocket. Soft lever could be air, a leak,  or as suggested, an internal seal failure in the master cylinder. As for the  fluid draining slowly, I occasionally come across a small chunk of black plastic covering the hole in the barb where it fits into the lever on Shimano brakes (usually creates a sluggish return of the lever), it doesn't happen often, but may be worth checking for.


 
Posted : 15/09/2023 7:20 am
 Yak
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+1 to all the above.

Also m6000 is quite old now. I have some from that era too and they have a master cylinder leak now so i need to swap the lever. Usually they will leak from one end or other in time, but I have probably had more caliper leaks though.

Swapping for another brand is utlimately better and cheaper than continually swapping levers or calipers.


 
Posted : 15/09/2023 7:32 am
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Time for Shigura?


 
Posted : 15/09/2023 7:58 am
 Yak
Posts: 6920
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<p style="text-align: left;">Time for Shigura?</p>

...if it's a caliper leak. But then the lever will leak at some point anyway. Best to go full Magura to be sure.


 
Posted : 15/09/2023 9:19 am
Posts: 360
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Topic starter
 

Thanks all for the advice. Nothing on the caliper, but the lever had quite a lot of fluid on it. I’m assuming I didn’t spill loads last time I tried to bleed, therefore new brakes are in order. I’ve fancied a set of Magura MT trail for a while now anyway!


 
Posted : 17/09/2023 1:48 pm

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