Pad adjustment screw "seized" on BR-M415 mechanical disc caliper

merYaFpS6v

I was fitting new pads on my son's bike which has Shimano BR-415 mechanical discs. On the front calliper, the pad adjustment screw (small allen bolt) simply won't budge in either direction, which means I can't adjust the caliper properly.

Before I go an get a replacement caliper (looks like the BR-M375 is the currently available replacement), does anyone have any idea what might be causing this?

On the rear caliper the screw is fine, and "clicks" nicely in each direction. I suspect there's some problem with the locking ring or clicking mechanism, but it's very hard to tell. Not really sure how the locking ring works either.

JBA

It's probably just corroded in place. You could try a bit of release oil on it and leave it to soak for a day or two. This is obviously best done with the wheel and pads removed to avoid contamination.
If it remains stuck then just try repositioning the caliper relative to the rotor and only adjust the outer pad position using the cable tension adjuster. Not ideal but may be enough to get another few months use out of the caliper.

merYaFpS6v

try repositioning the caliper relative to the rotor and only adjust the outer pad position using the cable tension adjuster

That's what I ended up doing. As you say, it's not ideal, but it's functional, at least for now.

Thanks, I'll try some WD40.