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Discussion Starter · #1 ·
Just replaced the pads on a set of Shimano Deore Hydraulic disc brakes and I noticed that both rotors have a slight drag. It's as if the pistons are adjusted to far out and need to be adjusted inward away from the rotor for proper clearance. Just trying to figure out how this is done??
 

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err, 27.5+
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Sometimes pistons can get dirty, or develop some stiction with their seals. You can lubricate them by pumping them out a bit (careful, don't pop them out) and using silicone spray lube or mineral oil on the piston shaft. Then work them in and out a few times to distribute the lube. Wipe excess off. This should help the pistons retract better. Also make sure that the return spring is still working, sometimes they get mauled installing the wheel into the frame.
 

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Discussion Starter · #3 ·
I don't believe the pistons are dirty as the bike is not that old. It's more like the new pads that I installed have a bit more material on them so the run closer to the rotors. I'm not sure if I need to open the bleeder screw and than try to push the pistons back for clearance or if he'll just have to ride it like that until the wear a bit? Seems there should be some way of adjusting or pushing them back a bit?
 

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I would leave the hydrolics alone. Pads are thicker now, so if that really bothers you, loosen the caliper and center it - it will eliminate the rub if you do it right.
 

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ride hard take risks
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Put a piece of hose on the caliper bleed nipple. Crack the bleed loose it should burp some fluid out, do not touch the lever. Snug the bleed then check if it is still dragging, If it is get a couple .015" feeler gauges and stick them between the pads and rotor then repeat the nipple burp. :thumbsup:

Your on the right track with your last comment. :drumroll:
 

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Maybe simply slightly warped rotors? Try resetting the pads by prying them apart with a tire lever or similar and then reinstalling?
 

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err, 27.5+
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tailwaters said:
I don't believe the pistons are dirty as the bike is not that old. It's more like the new pads that I installed have a bit more material on them so the run closer to the rotors. I'm not sure if I need to open the bleeder screw and than try to push the pistons back for clearance or if he'll just have to ride it like that until the wear a bit? Seems there should be some way of adjusting or pushing them back a bit?
Pull the pads out and push the pistons all the way into the caliper using the box end of a box end wrench ( find a 10mm works well). I don't recall if the deore has a center pin on the piston, but if it does take care not to break or bend it by being careless with the wrench positioning. If you can't fully seat the pistons, then there is too much fluid in the system. In this case I typically loosen the screws on the reservoir so it can vent/dribble out as I press the pistons in. Then tighten them back up and ride off into the sunset ;)
 
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