SRAM Guide R disc brake jammimg

[Tim Hall]

Well not quite jamming, but dragging on the disc.  I think it's a heat related issue, as they were fine (once I'd recentrered them by looseniung the mounting bolts, squeezing and holding the lever and tightening the bolts). But today when I got the Pino out for a pre ride clean, the rear brake was quite draggy.

I've not had a hydraulic disc braked bike before, so all this is new magic to me. I don't have a bleed kit (yet).

I tried pushing the pads apart with a suitable tool but no joy. I loosened the bleed screw on the lever and did the same. Some movement, so I though all was good, but no, still dragging. Possibly less, it's hard to say.  There's no bite point adjust on the levers. The front is OK.

Before I FUBAR it, any suggestions?  I'm planning to ride tomorrow in the scorchio heat.

[AuldThumper]

I believe these are the brakes that suffer swollen pistons in the brake lever.
Does the lever feel stiff in operation?

You could try cracking a hydraulic fitting. If it releases a drop of fluid and the caliper frees up then the problem is in the lever

[Tim Hall]

Ah, that's useful info, thanks.  I'll give it a go when I've got 5 minutes.

On the ride on Sunday, I left the bike in full sun while we went indoors for milkshakes. I could hardly move the bike ehen we came out again. Poured some water over the caliper to maybe bring the temperature down, which seemed to work. Or it was just coincidence. Left it in the shade at lunchtime and all was well.

[AuldThumper]

That sounds like a master cylinder problem to me
If the master (brake lever) cylinder fails to retract fully it leaves the bleed port into the reservoir closed allowing the system to build pressure as the fluid warms and expands
It could be pistons stuck in the caliper but given there's a known problem in the levers (Google confirmed my memory amazingly) I'd be inclined to suspect them

https://singletrackworld.com/forum/topic/sram-guide-squidgy-stuck-lever/