Brake Fade/Air in System

[HisNibbs]

Hi folks,

Having just bought a T3 '71 Fastback after not owning one for about 15 years and driving it nearly 300 miles this weekend I can't really remember why I got rid of my Squareback all those years ago, they're still ace!

Anyway to the question.

On picking the car up the (very, very knowledgable enthusiast) chap I bought it from informed me that despite bleeding the brakes they are still spongey.
He flushed the entire system through with new brake fluid, and bled all air from the system in the correct order.
The brakes are then firm, but left overnight they get spongey again, air can then be bled from Front LHS and Rear LHS.
If you bleed the brakes and then leave the brakes applied (using a handy length of broom pole from seat to peddle) the brakes remain firm and usable, however on collecting the car and driving back the 300 miles to home the peddle got softer and softer, and the last mile was a little alarming, and I utilised the hand brake. The hand brake BTW is solid and only requires a few clicks to come on and remain solid.
All brake linings are new, but even given that the pads are bedding in the peddle travel is unacceptable going almost to the floor (bulkhead) over the course of the journey. And if feels definitely like air in the system, because if you pump the brakes they do firm up a bit.

I am leaning towards a master cylinder overhaul, but the question is, could it be anything else? All pipes are in very good condition and there appears to be no fluid leaks down any of the wheels or in any of the wheel arches. And the reservoir remains spot on the full mark despite the 300 mile journey.

Anyone have anything else that I might look at? Or would just replacing the brake master cylinder do it?

There is no servo if memory serves (forgive me, it's been 15 years since last I wielded a spanner on an aircooled vdub), so it's not likely to be that then is it? (unless I am mistaken)

Can you buy a NoS master cylinder? Or is there an aftermarket version? Or is there an overhaul kit, and is one available?

Any help gratefully received.

Have spoken to Dave (Hi Dave) and am in the process of joining this august and wonderful club.

As an aside, having used the "date your VW guide" I have worked out that from the example plate on the website which shows a production week 18 plate which is 20 days before mine (week 20) and is 15968 chassis numbers before mine, therefore they were producing circa 798 cars a day! If you include Sundays, 887 a day if they had a day of rest! WOW! Amazing, but do the chassis numbers include Beetles?

Anyway I digress, any help on the master cylinder/brake fade question would be most appreciated.