Brake Master Cylinder

[MD]

Started servicing some of my spare parts on the shelf as back up supplies starting with a couple of Alfetta ATE 22mm brake master cylinders.When I pulled the pistons and cup assemblies out, I found the cup configurations were different in each one.

I decided to consult the Haynes Workshop Manual but I suspect that the illustration provided is wrong. See photos. I believe the cup in the primary circuit with arrow is facing the wrong way.

Anybody with a different manual or personal experience with this BMC assembly care to comment?

[MD]

Bump

[festy]

I just pulled apart an old Alfetta m/c to compare to your pics, but mine has square rather than tapered seals.

[colcol]

Went through this about a year ago with the 33, nothing online and the workshop manuals were very poorly detailed, but the seals on the repair kit seemed different to the original ones in the master cylinder and in the drawing.
Ended up buying a new one, as opposed to putting it together wrong and bleeding the brakes again and it not working, and with a new one the cylinder bores are all new and not scored, Colin.

[MD]

Yeah I got no problem with that approach at all Col.
This type of ATE master has been in use for decades by Alfa and it is also one used by other German cars so parts are relatively easy to obtain and the unit can be repaired provided the pistons and cylinder bore are good which is the case with mine. I repaired it for the price of $27 having paid that for the rubber kit.
The one special thing that you can do at this time if the bore is pitted is to have it stainless or brass lined before fitting a new rubber kit. This makes a master cylinder for life.

I did a bit more research and assembled mine as per the attached photos which should help anyone inclined to do your own.

[MD]

festy,

Never seen "O" rings in an Alfetta BMC but have seen them in the servo boosters of 105 cars. "O" rings in this application are not as safe in my opinion as cups because the "O" rings can (and do) collapse under pressure which can lead to total brake failure- just ask me.

If that was my Alfetta, I would be installing an ATE cup type BMC pronto.

[David Mills]

Went through this about a year ago with the 33, nothing online and the workshop manuals were very poorly detailed, but the seals on the repair kit seemed different to the original ones in the master cylinder and in the drawing.
Ended up buying a new one, as opposed to putting it together wrong and bleeding the brakes again and it not working, and with a new one the cylinder bores are all new and not scored, Colin.

Where did you buy the new cylinder Col?

[four90s]

Beautiful diagram MD.

I'll keep a copy of that if that's all right.

Regards
Steve
Adelaide

[Darryl]

Thanks for the pic of the master cylinder assembly MD.. Only replying so I can find this again without having to search through all your words of wisdom, again .