pedal goes to floor , almost no braking

[Tappy]

Hi Guys ,

Coming closer to revive my spider, I've braking problems

What is done, about 4 years ago front calipers were replaced by refurbished ones, about a year ago rear axle was rebuilt, new calipers installed there never (since I've bought it 20 years ago) was a rear brake compensator installed

part of the brake line on the rear axle is new

Brakes being bled over 5 times now, probably 2 Liter of brake fluid went through
Before this I don't think last 20 years or so brake fluid was replaced, pretty sure DOT 4 was introduced to the system in the past, as DOT3 is not widely available in car part shops in Belgium (on top mechanics keep saying it is the same but better to use DOT 4…)

I no longer have leaks, driver side copper washer on the banjo bolt had a small leakage after replacing all fluid stays in the system.

Nevertheless, after just bleeding the pedal feels firm and breaks seems to be working

Once….

Second time they don't scaring the crap out of me.

On top the emergency brake catches only on one side of the car, and does not have the strength to stop the car.
The cable is being replaced with a brand new one.

I'm not sure, but these can be both different problems, just want to get all info here.

I'm suspecting the master cylinder to be seized, as the symptoms all point in this direction ?
Any comments on my diagnosis or things to do before replacing this one ?

[18Fiatsandcounting]

If the bleeding process seems OK and the brakes work initially, this is likely a problem with the master cylinder. It's not seized, but it's not building up pressure. Enough pressure to bleed the system, but not enough to operate the brakes.

This happened to me once when I rebuilt the master cylinder with new seals, and the brakes seemed fine for about 50 miles but then totally disappeared. I had to drive home almost 50 miles with no brakes.... That was scary.... The solution was to put the original seals back in the master cylinder and then it worked fine again.

Let us know if the new brake cable helps. This doesn't usually affect the hydraulic brakes, but the cable can become "unbalanced" between left and right. Or stuck on one side. Note that the Fiat emergency brakes are never really very strong. Just not a good design.

-Bryan

[Tappy]

Issue resolved , master cilinder replaced some hours of bleeding and a bad surface at the clamps due to sandblasting prevented proper sealing of the copper washers