Frank's brakes weren't too crash hot even after swapping the front and brake mechanicals. So we had a look at the booster, which was the original, tiny diesel one.
Upon closer inspection, two things were clear. One - the master cylinder was completely shot. And two, the booster was filled with brake fluid.
Unbolt from inside the cabin as the rod protrudes through the firewall:
This is how much fluid came out of the booster. Not good.
At leas this is very accessible in Frank!
The replacement booster is from a 1996 Seat Cordoba and fits up perfectly. It only needs a little modification.
Remove the locking bracket from the old one, and the one from the new. You need the old one.
Enlarge the hole using a lathe.
See the ball? That needs to be gone.
All gone now!
Turn down the shaft and put a lovely VW thread on it.
And bolt the old bits back on.
And it all just slots back in!
We needed to replace a couple of brake lines so you need some line...
And a pipe bender...
Finally, plug the Cordoba master cylinder in and pop in the reservoir bottle. The bottle is too tall with the original sensor cap in place so we used a Mk 1 Golf cap. I might get a sensor reservoir from German Auto Parts later, they have a Mk 3 bottle with sensor that I think will fit.