On 11/22/2019 8:50 AM, jbeattie wrote:
On Friday, November 22, 2019 at 6:01:59 AM UTC-8, Andrew Chaplin wrote:
On Wednesday, November 20, 2019 at 9:02:18 PM UTC-5, jbeattie wrote:
On Wednesday, November 20, 2019 at 11:07:59 AM UTC-8, Andrew Chaplin wrote:
I have been riding a gravel bike (Kona Rove NRB DL https://www.konaworld.com/rove_nrb_dl.cfm) for a year now. It has developed a tendency to drag the pads of the front brakes against the disc. I recently had the pads and rotor, front and rear, replaced (about 5,000 Km of use). As I ride, a noise comes from the front brake that suggests that the pads are touching the rotor, and it increases in volume until I "blip" the lever, which makes it go away for maybe another Km or so--or less.

Has anyone encountered this before? if yes, how did you solve it?

Yikes, you must do a lot of braking. 3K miles for a rotor doesn't seem like much.

Anyway, you may just need to reset your pistons.
https://www.epicbleedsolutions.com/r...liper-pistons/
If that doesn't work, then the next thing is checking to make sure the caliper
is centered. Like Andrew says, just follow the instructions for
installation/alignment. https://www.youtube.com/watch?v=uk_nC9anQcM&t=13s

If that doesn't do it, check to make sure that both pistons are retracting.
I have a piston that will drag occasionally, and I need to clean it. Follow
this routine: https://www.youtube.com/watch?v=vQXF...&feature=youtu

Another outside possibility is that the system is over-filled, so if all else
fails, bleed it and refill it.

And if all that doesn't work, buy a new caliper -- you could just have a bad
one (there can be issues with seals and pistons). The notion that a hydraulic
road disc will inevitably drag and make noise is wrong. I have hydraulic discs
on three bikes, and they drag only when there is an issue.

I took it to the bike shop where I had the brake work done. They may have
damaged the seals as, after working on it and taking it for a test ride, front
braking faded quickly and there was oil leaking.

You need a different shop!

From where is the oil leaking? You can have piston seal issues as well as other issues that are relatively easy to fix, like a leaking hose connection. Other leaks can be: (1) bad internal o-ring and leaking from the seam between the two caliper halves. This was a known problem on certain RS785s, the predecessor of your caliper. I replaced the internal o-ring seal on one caliper (and now have a bag of redundant little o-rings), and that caliper woks like a charm. (2) You can also get leaking from the fill port because the stopper screw is not seating. You just pull that out, make sure the o-ring on the screw is seated properly and that the screw-seat is clean and clear. And (3) you can have a piston seal leak, which could repair itself when the piston is pushed back in. You could even have a cracked piston. Anyway, those things are reparable, although I have never replaced a piston or seal. Youtube has videos. It's probably easier buying a new caliper, which are not horrib
ly expensive. BTW, if you have oil on the pad, it will never work right again regardless of cleaning, sanding, etc., etc. At least that's been my experience. The pad will work marginally O.K., but I'd just buy a new set.

-- Jay Beattie.


If he dropped it off without leaks and received it leaking,
a full rebuild or replacement ought to be free.

Except for the medical racket, that's normal to most other
businesses.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971