Disk Brake Witchcraft Pt 2.

[doctorstewie]

Hi Folks, I really should not be this baffled by fairly simple stuff.
I just replaced the pads on my Magura Julies and they are sticking badly. I have made sure that after putting them in I did as the manual says and pressed them into place to make sure the pistons are pushed back, then pumped the brakes but the pads are dragging on the disk like there is no tomorrow.
Any suggestions anyone? it's driving me nuts.

 

[mattr]

Did you fill/bleed the brakes with worn pads in? The system may be slightly overfilled, this will make the new pads stick out very very slightly too much. Open a bleed nipple somewhere and drain out a tiny bit, or rebleed with pistons pushed RIGHT into the caliper.
Are you using genuine pads? Some aftermarket pads may be *slightly* thicker than stock , or have paint on the back plates. Sand the paint off, or file the face of the pad down. Slightly.
Are you using genuine discs? Some are slightly thicker than others. (But you haven't changed this so i doubt its the issue)

Did you clean everything? If only one pad is rubbing you may have got some ick into the piston bore which is stopping it retracting. Pads out, disc out, bloody good clean, cycle the pistons in and out a bit too. Bit of the correct fluid on the seal will help as well.

 

[doctorstewie]

Thanks very much I'll have a go through that lot. I am using Uberbike pads, so I'll have a close look at them, though the bleed and refill was done using the worn pads so I feel you may have hot that particular nail on the head.
Cheers for the help

 

[02gf74]

Re:

No need to mess with uberbike pads. Fingers crossed its overfilled system else the pistons could be corroded, with worn pads they stick out further, so are exposed to moisture, then when you fit new pads, the pistons are pushed in.

 

[dazdc5]

Re:

Uberbike pads!!! Hell, get ready for some serious squeal!

Never again :facepalm:

 

[doctorstewie]

Right now I'd settle for the buggers working...

 

[legrandefromage]

Its a shame you are not nearer, I could have them running within a reasonable time.

 

[doctorstewie]

Cheers LGF, but I'll sort the little swines. It's a matter of pride now. ( And having more than half an hour at a time, and being distracted by a Kona.) I find stuff tends to work in my head if I do something else while pondering it.

 

[doctorstewie]

They WORK!!! Aha! Aha! Aaaaaahaaahaahaahaahaahaahaah!!
It's ALIVE!

*cough*
Sorry.
yeah I did a combination of things: bit of sanding to the back of the pads, a bit of screwdriver violation of the calipers and some bleeding. ( me, as well as the brakes )
A tiny amount of dragging but bearing in mind the pads are new I have been led to believe this is usual and they will wear in.

 

[Osella]

The other thing with pad drag is alignment, unlike most where you can use the standard loosen bolts, grab lever until pads level up against the rotor, tighten bolts, method - I've found with Julies (albeit mine have been the next gen versions from yours) I still had pad rub on mine so I align them by eye (torch or light underneath & look down through the caliper) until the pads are parallel to the rotor, gentle spin to confirm & tighten the bolts back up.

Had all the same kinds of issues at first too - see Julies are a great introduction to discs. Like driving an original Mini - nothing works quite right to begin with, but you soon learn a hell of a lot about how to fix things..

If you're still getting any issues tho, don't be afraid to grab a flat-bladed screwdriver or similar large flat blade (you might have a piston press already?) and really shove the pistons back in (remember, you're pushing the fluid in these all the way back into the reservoir at the lever).
If still an ongoing problem, use a pipette or syringe to maybe take a little fluid out of the reservoir until they are returning fully as others have suggested.