Hi,
after each stop longer then a few minutes, I practically lose my brakes. The piston retracts all the way into the pump (pedal hits it waaay down in it's travel), and I can only apply a very small force, much like engine braking. It gets gradually better after each braking attempt. I don't know if this is related, but yesterday was VERY rainy and all my brakes definitely got wet (my new frame has no shields under the front section), I even lost my flasher unit because I get a lot of water coming around the windscreen seal :/ And the new unit is suitable for cars with additional side indicators, so it blinks crazy fast now :/
Anyway, what the fuck is wrong with my brakes? I need to drive, but this is outright dangerous, I don't know what to do about this and I want to get it fixed fast.

Where the brakes blead properly?

Take a dive to look at the back of the master cylinder. Sounds like the piston doesn't slide back after hitting the pedal. Did you fit a new master cylinder recently?

James:
I assume so, I had no problems in the previous 3000 km, pedal was firm and braking was excellent.

2CViking: Yes, that's exactly what it is. The master cylinder isn't new.

The problem with mine was at the back of the master culinder where the pedal rod pushes the pistons of the master cylinder . If you have green fluid there (lhm) then you are losing fluids.

If the piston or should I say seals are buggered, you have no hope except replacing the master cylinder.

I think the non-return valve in the inner piston is gone. A 2CV master cylinder is very expensive here, but for 1/3 of the price I can get a new Visa/C15 master cylinder with the same pistons (17,46 mm diameter) and move them into my old one. There are some ways of extracting those bloody split pins from the cylinder.

Saurus,
I thought your car had disc brakes, therefore Visa/C15 master cylinder seals would not be compatible with the LHM fluid which the rest of your system needs.

ken

Me and several of my 2CV friends use DOT4 in LHM system without problems. As far as new seals are considered, this is a myth to me.

Nooo!
DOT3 or DOT4 fluid in an LHM system will produce the symptoms you've got at the moment, usually within a few weeks or less of it being added to the system.

Topping up the master cylinder reservoir with the wrong fluid takes a bit longer to cause the damage, but the result is the same, a master cylinder destroyed, probably calipers and rear cylinders dragging or ruined if they've been bled...

http://www.totaloil.com.au/Pages/content/NT0000C146.pdf

Note that adding LHM to a 'conventional brake fluid' system has the same effect.

ken