I should add that it is the 20mm ATE master cylinder, if that matters. Thanks!

 

Although it may not be the exact same master cylinder, the photos & details in this thread may prove useful.

 

I'm looing for an exploded view of the 1973 GTV 2000 brake master cylinder. I have the American 2 stage type. I have search everywhere and can not find it, not even here on this appropriately marked thread in the 105/115 section. Why its called Exploded View is beyond me. When I took my Master Cylinder apart it was stuck and I had to use compressed air to get it apart. All the parts went flying and I hope I found them all but I need to know how to reassemble the MC. Please advise.

 

What brand is it?

 

No idea? Stock Factory, I suppose. I didn't see markings on the casting. No matter the brand, they should all be the same on the inside. Centerline sells them.

Brake Master Cylinder 115, 116, 119 | Centerline Alfa, OEM & Aftermarket Alfa Romeo Car Parts

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models

www.centerlinealfa.com

| Centerline Alfa, OEM & Aftermarket Alfa Romeo Car Parts

Centerline International is the leading supplier of restoration, performance, and maintenance parts for all Alfa Romeo models

www.centerlinealfa.com

 

Given that your car is nearly 50 years old, there's is a really good chance the master cylinder has been changed at least once.

There were two suppliers of brake boosters and master cylinders, Benditalia and Ate. The internal parts are different. Ate master cylinders will have and Ate logo on the side and show the bore diameter of 20 or 22 (mm).

Here are a couple of threads:

Brake Master Cylinder Rebuild help

1977 Spider, ATE master cylinder that blew a rear seal, filled up the booster. I'm going the rebuild route this time, ( so far ) with ATE kit, 20mm bore. The bore is in good shape, all other hard parts too. But I need help figuring out how to access these two rubber cups? No end screw or visible...

www.alfabb.com

Tandem Brake Master Cylinder...how it works

The following is a description of how a tandem brake master cylinder (MC) works under various conditions. Although one brake MC and it’s components may look physically different than another, their functions are the same. The first pic shows the components of a tandem MC (not all components are...

www.alfabb.com

If these are of no help to you, please post pictures of all of the bits and the community will help you sort them out.

 

The one in the picture above. Thank You

 

but the problem with the above picture.. does not show in what direction the seals go.. they have lips..( for lack of a better word).. to them..so be carefull on rebuilding the m/c

 

Bianchi2, I know exactly what you mean. Just keep this in mind, the fatter end of a seal is always the side that pushes the fluid out. So all fatter ends of any of the 3 seals should be towards the left end of the picture above.

 

....So all fatter ends of any of the 3 seals should be towards the left end of the picture above.

are you then saying the lips (fatter ends) of all the seals face the same direction?
you sure about that?....I seem to recall the seals face away from each other on the piston....

 

I've only got experience with Ate master cylinders. And Dom, you are right. Each of the pistons has a seal that points to the rear of the car. And, there are two types of piston seals. The best diagram I have for right now is this one. It's a bit on the small side.

Papajam's post "Tandem Brake Master Cylinder...How it works" has a couple of very nicely done graphics that show how each piston seal should be oriented. I linked to that post above.