The secondary piston in my 1979 series 1 brake master cylinder is seized
Does any one have a suggestion how to free it
It is stuck fully in

 

Other then a rebuild/hone, a new one is the best choice.

 

I second buying a new unit......brakes are too important. I would be going through the whole system personally

 

Best to replace.

If you're stuck repairing, you could try to blow it out by making an adapter to hook your compressor up to the outlet, or by drilling the seized piece with a long drill bit and screwing a long wood screw in to the hole and pulling out.

Best to replace though.

 

Seriously.....$49 - $79.....why go through the headache of doing anything else?

1979 MAZDA RX-7 1.1L R2 Master Cylinder | RockAuto

Or better question...why wouldn't you replace faulty 30+ year old brake parts?

 

Replace it. Rockauto is cheapest prob

 

Can soak it in brake fluid on a bench to try and get it free.......but seriously you should just replace it!