Rear brake - disc warm, binding?

[purplebikeunicorn]

After all the faff of bleeding new fluid round the brakes, I took the bike out and had a bit of a play in the gravel. Front ABS I could activate (with flashing light on the dash and expected pulsing and I stayed upright), and rear I think came on (as I didn't slide the rear), but no light on the dash. Good strong braking effort though 60 - 20 odd as well (all I felt comfortable doing on the piece of road I was on!).

However, I noticed that the front discs were cold, but the rear disc felt warm (but not so hot I couldn't touch it) when I got back - this was approx 3 mins after riding. After another 2 minutes more, it had cooled down that it was the same as the front. On the centre stand (when it's now cooled down), the wheel does almost a full rotation before stopping by itself, but does sound a little growly (like it did pushing it round, but I thought this was just some surface corrosion as I haven't ridden for a couple of weeks!). There is a nice lot of corrosion on the slide pin through the pad ears I could see at first glance.

Looking at the access to the caliper and OEM exhaust possibly in the way, how much of a git is the rear caliper to get off and clean?

[Gert]

Could be that the brake pedal may be starting to bind. See if cleaning and applying some grease / lube to the brake pedal pivot pin makes any difference.

[purplebikeunicorn]

I'm almost certain I wasn't riding the rear brake (I make an effort to move my foot), and the pedal is free to move. Had a look at Dr Vstroms video and will have a look and ensure all the pins are free today 👍

[Rixington43]

Drift pins are a good shout, check the rubber boots for splits or cracks as well, I had to replace 1 of mine and the caliper has remained free ever since after filling the boots with a good coating of grease.
Also worth pushing the piston all the way back into its bore, leave it for a few hours and then pump the brake back up, usually frees them up a bit.
The rear disc will get warmer and stay warmer than the front I'd guess due to smaller size, single disc and less airflow but well worth checking everything over if it sounds draggy when wheeling the bike.

[purplebikeunicorn]

So, what a shit that rear brake is for access!

Took the pad pin out, cleaned it up with some light sandpaper and wd40, there's a noticeable divot where the inboard pad would sit and just generally a bit shit so I've added it to the parts list (I've got a basket going with Webike - this pin is £22.50 at fowler's, and £3 with them), although thinking about it, this pad doesn't move does it? It's only the outboard pad that does!

The rest of the caliper pins are free - I couldn't get the caliper off as had nothing small enough to take off the forward most pin (and you can't pivot the caliper enough over the disc with the hose attached). This will be a job for winter when the back end is off I think!

Piston also looks fairly clean, pumped it out a bit and it pushed back with finger pressure. Pads look fairly even, inboard pad possibly a bit less worn but it's minute.

And now it's raining, typical 😜

[Gert]

My suggestion of the brake peddle pivot, as a possible cause of the binding, is based on a previous discussion: https://www.v-strom.co.uk/smf/index.php?topic=21693.0

FWIW, the front brake rotors are floating (bobbins), while the rear brake rotor is fixed.

[purplebikeunicorn]

Hi Gert,

The rear brake pedal pivot isn't binding at all and has a very good snap back throughout its movement. Its held on with a circlip isn't it? If I can find my circlip pliers it'll be checked this weekend or next if I can't!

[kwackboy]

Reading what you have said, it appears to me that apart from cleaning the caliper components, you have nothing wrong with the rear brake.

The rear rotor will be warmer than the fronts because used on it own it will produce more heat and it receives less air flow.

As for drag and the noise when spinning on the centre stand, this is pretty normal due to the drive chain and the pads slightly rubbing on the disc.

[purplebikeunicorn]

Yep, I think that's what it boils down to. I'll check again after I next ride and will see how we fair! Thanks for the tips