Thread: Series 2a master cylinder.

Sounds like your first MC had an issue (something inside was sticking and not releasing pressure.

Your 2nd MC sounds fine, it just sounds like there is still a small amount of air in the system.

There is a difference in bore between 88" and 109" MCs, and there is a noticeable difference in size. You couldn't have the wrong MC unless your previous one was also incorrect.

When I bought my 109" IIA it was fitted with an 88" CB-type MC, and the brakes worked well, and the pedal stopped about 33% of the way down. The smaller bore of the SWB MC meant the brakes required much less effort! However ajustment was finicky.

Check where the problem is by clamping off the three hoses, and bleeding each section separately. With all hoses clamped, pedal should be solid with only the free play on the rod.

For each front wheel (and the two back wheels) separately, if you adjust the shoes till they are locked against the drum, then any additional free play must be air, but if it is solid but you get free play when you adjust the shoes correctly, then the problem is not air, but with the brake shoes or springs incorrectly assembled, drum out of spec etc.

And remember that you can bleed at any union.

John

Try using the clamp method as suggested by JD and make up one of these, it works like a charm.

I'll give it a try, I did make up one of those vacuum bleeders like in the pic, and it did work well but it must still have air somewhere, with the three flex hoses clamped the pedal is good. So there must be air somewhere. Does anyone bleed the brakes with the shoes adjusted up against the drum? Thanks for your help guys!!!! Much appreciated. I was thinking the only answer was a box of matches!! Ha ha