If master cylinder seal fails, what happens?

[sugarwood]

If the seal tears, do you lose your brakes entirely and drive into a wall?
Just wondering about the shelf life of this part.

[Bob Kontak]

Let's just say compromised. Your pedal will be soft but you can pump it up quickly to where it feels better.

There may be levels of being compromised?

However, you have a dual braking system. One side can go ti*s up, in the ditch, and the other side (seal) will stop you.

I am running my 1981 seals.

[steely]

+1 w/ Bob there.

Mine didn't go catastrophic, but I suspected an issue, investigated and addressed it a couple years ago.

I found a small leak, and I never noticed it before I looked under the frunk carpet and looked under the dash below the steering column (or, beneath the master brake cylinder but in the cabin - there is a little plastic plug, and the bf dripped extremely slowly).

I found it by accident when I was refreshing my pedal cluster. My brakes seemed ok, but my clutch was a bit tough btw (slave cyl) and I thought I might be leaking fluid albeit very slowly. But I never found any on the ground. Instead, the black carpet took some, and the rest dripped to the smuggler box and into infinity. And we aren't talking a lot.

I replaced it, the master clutch and clutch slave cylinders, some old lines and even the reservoir as well. Brakes are fine and clutch pedal action is lighter btw.

I can't answer your shelf life question, but you can use me as a data point.

[manbridge 74]

They fail slowly in my experience. But we once had a car in where someone had added power steering fluid or oil by mistake. Owner reported it failed quickly. Ended up replacing all rubber based components.