The front brakes stop the bike very well and I've felt the ABS kick in before so I know it's working. I think it's that the pistons aren't returning at all on one side.

 

You at least know which one of the pistons is not returning, it is the one with the worn pads.

 

Is there a rebuild kit for the brembos? I thought I saw a thread complaining that they dont exist.

edit - looks like you can put something together.

See if there's anything helpful here - https://www.google.com/search?q=harl...e:hdforums.com

 

It's not really that bad. If you got just a little more spin, I would say welcome to no-floating or semi-floating rotor/discs. For the hell of it, make sure the rotors true and aligned. Definitely do the rebuild - it's easy, it's fun, it's cheap. Those pistons look pretty grimy.

 

pistons do not return the is no spring to return them unlike brakes shoes with return springs. when you release the brake lever you just release the pressure on the pads
they stay right there just no pressure on them

 

I would flush the entire system very well, and ride it.
Reevaluate the system later, if needed.

 

My FLSTS is a no-float and spins free. With a DIY rebuild, how do I bleed the brakes without a digital technician? Trailer it to dealer?

 

Dealer rebuilt the master cylinder and flushed fluid. Symptom persists which is why I'm trying to address it this winter.

 

disc brakes have some drag at all times, with disc they should not spin freely, the pads are always in contact with the disc. How much drag is too much is hard to describe, you should be able to turn the wheel easily by hand and the drag should be constant no hard to turn less effort to turn areas. That being said from the pictures you pistons in the calipers look corroded and could very well not be sliding back as others said , rebuilding the calipers is easy and pretty cheap to do but either replace the pistons or make sure the clean up well with no pitting or roughness. if the wheel spins easily then up you may need to check for rotor warpage. Hard to expl;ain maybe find a indy or dealer you trust to double check your brakes and see if they think the drag is excessive.

 

What's the runout on the discs?