rubbing brakes

[Wonko The Sane]

I've had the callipers on the ZZR aligned so that the centreline of the calliper and the centreline of the disk are aligned instead of sitting off centre.

One of the callipers had been sitting at an angle and so the pads in this calliper had worn at an angle - as there's a fair bit of wear left in them we've swapped them to even the wear out and they're rubbing a bit, on the way home from the garage they started scraping unless I brake slightly.

chap at the garage reckons this is fine and just the pads wearing back to the correct shape and it'll go away soon enough.

The brakes are hot when I stop even though I've done less than 10 miles and the bike is a pig to push.

I've got a new set of pads - should I just stick those in or just accept a bit of noise and heat?
____________________
Looking to pass your CBT / Bike tests in Bury Lancashire? try www.focusridertraining.co.uk Would recommend.
They're also on Facebook https://www.facebook.com/pages/Focus-Rider-Training/196832923734251

[RS_Raz]

Fit the new pads. Never compromise with brakes.

[Papa Lazarou]

[Wonko The Sane]

The brakes work and stop the bike well, it's just the current rubbing and slightly soft lever that I'm wanting to double check

anyone taken pads out, serviced brakes and put the pads in having not kept track of which way rounds the pads were and had similar?
____________________
Looking to pass your CBT / Bike tests in Bury Lancashire? try www.focusridertraining.co.uk Would recommend.
They're also on Facebook https://www.facebook.com/pages/Focus-Rider-Training/196832923734251

[MCN]

I don't know what you mean by 'centre lines'. With respect to what?

Anyway, the rubbing and soft feel is probably due to the pad contacting the disc on the 'high-spot' created by the 'misalignment' and then being pushed onto the disc by increased piston travel. That will account for the 'soft feel' as you are effectively not applying force to a flat/even surface.
This effect is not optimal as it introduces some delay into braking time and a risk of the piston/s cocking in the cylinder.

The heat is likely due to the pad not returning to a designed 'brakes off' state when the lever is released. The rubbing/scraping will produce heat.

Hydraulic Disc brakes rely on the flex in the piston/cylinder seals to allow the piston to rest in a 'brake off' position.
They self-adjust because the more the pad wears the more the piston can move out the cylinder (and squeeze through the seals). There is no spring or other force to pull the piston back but the design of the piston seals return to a rest position and pull the piston off slightly. (Micro-millimetres) There is still very very slight pad contact with the disc but that doesn't create much friction.
This is why a disc brake can feel tight if the bike has been parked for some time and the disc gets a bit of rust on. Until you scrape the rust film off the pads will grip the disc.

The pad will eventually 'conform' to the alignment of the calliper but I would investigate why the calliper is off-set and address that.
____________________
Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[Papa Lazarou]

The other risk you are taking is that the old pads are constantly rubbing on the disc. You mentioned that the disc is getting red hot and the brakes are binding. Unless the old pads settle in very quickly, you risk warping the disc. That would cost much more than a new set of pads.

It's a simple and cheap fix. Avoid it getting expensive and risking brake failure.

[Gazz]

I had an off a couple of years back because of the same thing. The front brakes heated up so much that they locked up the front wheel. Lesson learned the hard way.

[Vincent]

Aye, new pads can bind at first but if your brakes are binding so much that it's difficult to push the bike then you shouldn't ride it I'm afraid. Personally, if I was stuck somewhere, I'd rather pull the offending pads out of the calliper and get home without that brake but I wouldn't recommend that course of action to everybody as it has it's own inherent dangers.
____________________
Space Is Deep

[Vincent]

[Wonko The Sane]

[Papa Lazarou]

[/quote]

yes, centre of calliper is aligned with the disk instead of being slightly offset

I've changed the pads, I can see on the old ones where they're starting to wear back to shape but perhaps best to go with the fit and forget solution of new pads.[/quote]

[Wonko The Sane]

20 miles later and the brakes are rubbing still (normal with new pads?) the calipers were serviced a few weeks ago so should be functioning properly.

Lever is firm for first time in my ownership, i'd gotten used to it being a bit soft.

disks are hot to the touch but calipers are not which is an improvement on last night.

am I now worrying about not a lot and just need to wait for it to bed in?
the brakes rubbing makes pushing the bike hard work.
____________________
Looking to pass your CBT / Bike tests in Bury Lancashire? try www.focusridertraining.co.uk Would recommend.
They're also on Facebook https://www.facebook.com/pages/Focus-Rider-Training/196832923734251

[P.addy]

Non OEM calipers I assume?

Service originals if so and stick them back on.

[Wonko The Sane]

[MCN]

[Wonko The Sane]

[MCN]

[Wonko The Sane]

[MCN]

[Vincent]

[Papa Lazarou]

[/quote]

On the ride use the brakes severely to get some heat in them. The heat can vaporise the friction material and bed the pads in better.
That means short hard pulses of the lever (without pulling a stoppie and be sure there's no dopey cnuts behind you. )[/quote]

20 miles is a lot.

[Wonko The Sane]

well, heat was getting into them, they were rubbing a bit too much making it hard to push the bike once stopped.

Took it steady on the way home letting the brakes cool from time to time - callipers were cool but brakes hot (I know they're meant to get hot from time to time)

The brake fluid reservoir was pretty much full so wondering if a bit too much fluid causing the pistons to not move back as much as they ought,

stopped about a mile from home and took a little bit of fluid out brakes were cooler when I got home (usually hot after a mile or so) and bike easier to shunt into where I park compared with when I left work.
____________________
Looking to pass your CBT / Bike tests in Bury Lancashire? try www.focusridertraining.co.uk Would recommend.
They're also on Facebook https://www.facebook.com/pages/Focus-Rider-Training/196832923734251

[Vincent]

Has the master cylinder got the rubber bellows thing in?
____________________
Space Is Deep

[Wonko The Sane]

[Vincent]

That bellows thing is quite important, it allows the fluid level to rise and drop without any more air getting in
____________________
Space Is Deep