1977 Z1000 Rear Master Cylinder O Ring
Posted: Sun Jan 25, 2026 1:35 pm
Hello all
I am looking at refurbishing the rear brake cylinder on my Z1000 A1. I found a couple of good videos (American) on you tube, one where the chap replaces the square section O-ring between the main body and the plastic reservoir. Would anyone have any links for the O-ring in the UK? I've had a search around but no luck. I know the normal piston and seals kit is available from Zpower, but obviously doesn't include the O-ring I'm after
Philippe very helpfully posted these sizes back in 2019.
One a separate note, were these original cylinders reasonably ok for actual stopping power or could I consider a more modern replacement? Am thinking something like the rear cylinder on my 93 750 zephyr, which does a great job. But then again am I expecting too much from the 1977 brake caliper itself?
Thanks
Paul
I am looking at refurbishing the rear brake cylinder on my Z1000 A1. I found a couple of good videos (American) on you tube, one where the chap replaces the square section O-ring between the main body and the plastic reservoir. Would anyone have any links for the O-ring in the UK? I've had a search around but no luck. I know the normal piston and seals kit is available from Zpower, but obviously doesn't include the O-ring I'm after
Philippe very helpfully posted these sizes back in 2019.
When it's leaking between the plastic cup and the alloy body you can replace the O-ring. It's easy to remove the cup, only two screws hold it there. The O-ring has an external diameter of 52 mm and is square. The height is 2,85 mm, the width is 2,35 mm.
I think you can find that O-ring in the UK somewhere
One a separate note, were these original cylinders reasonably ok for actual stopping power or could I consider a more modern replacement? Am thinking something like the rear cylinder on my 93 750 zephyr, which does a great job. But then again am I expecting too much from the 1977 brake caliper itself?
Thanks
Paul