Front brake cylinder small bolt thread

[baz_d69]

Does anyone know what thread the small bolt is on the front brake cylinder? It's on a '57 1000. Also, what purpose does the bolt serve? Seems a bit odd in terms of placement (and size) if it's merely to keep the cylinder in place (right next to the bigger one!).

Cheers!

[bmcecosse]

I 'think' it's 1/4" UNF.. Obviously it's there to hold the cylinder nice and square - and it's small because there is so little space!