BM57 master cylinder, what is this hole and why is it leaking?

[Benkid]

Bleeding up new brake setup, heard a bang and then this started squirting fluid out?



any ideas what it is and why it leaks?

[shogun]

Is the allen screw still in place?
If so, tighten or remove and refit with loctite.
If not, refit.

[Benkid]

Nothing in there. Doesn't even appear to have a thread

I managed to swap it with another BM57 I had so all is fine now. I will try find that screw though so I can sell this on if it's not broken.

[gonzomagic]

Did you get to the bottom of this?

[nattman]

If memory serves this hole is for when the seals have gone in the cylinder, leaks through as a sort of pressure release /tell tale. Could be wrong though.

[Clarkey]

Is it? Mine had nothing in it and it dripped so I just banged a screw in it. If that is true then I'll get rebuilding it, I do have excessive rear bias but then I also have larger than stock front piston area.

[gonzomagic]

Mine kept poping after it was rebuilt. The rebuilt was done in front of me, so certain it was done properly. Bought the rebuild kit also from Bigg RED. Hence, I have seen a few that have a screw in them, as opposed to a rubber grommit like mine did? Do people just plug it?