Cabbie Rear Brake Conversion to Disc (1982)

Further to the above topic re rear disc conversion, I'd be grateful if someone would advise me about the two inline fittings shown on the rear brake lines from and to the master cylinder shown in the attached photo.  Are these also some type of regulators and should they be removed as a new regulator valve is being fitted?  What are they for?

They are one way valves and should only be fitted with rear drums as they would cause the calipers to bind.

There were two methods of setting and controlling the rear bias, one fitted to the rear and spring loaded to the axle. The other was pro portioning valves screwed directly into the bottom of the master cylinder, which restricted the flow to the rear brakes. There were two types of these, one for rear disks (16V Scirocco) and the other for rear drums (mainly late model cabbies).

Thanks, good that you warned me!   Now I need to get the rest of the picture I' e asked about in the earlier post. 

your mc looks a bit shafted! if you go for a mk2 golf one they only have 4 holes so nowhere for the brake light switches to go if yours are mounted on the MC.

on my cabrio i binned those 2 valves and fitted mk2/3 brake pipe T pieces in their place, this helped me in 2 ways. first it gave me holes for my brake light switches and 2nd allowed me to bin the valves without having to redo the lines

I fear you are right about the mc, so no doubt I'll be investing in a new one.  Thanks for the advice about the T pieces.  Did you have two brake light switches or did you just blank off one of them?  Sorry if that's a dumb question, but I haven't studied the switch set-up yet.

there are 2 switches usually, I fitted them both but 1 of them was broken (NOS!) so i had to unplug it and make do with just the 1 switch

if i was to do it again id convert to late cab/rocco pedal mounted switch setup

Yet again thanks for the advice!  I've a lot to do before I reach this stage, so I'll probably be pleading for help again later.  Which particular MC did you use, as I see at least three variants on VW Heritage?   

I had a mk2 gofl 9" brake servo and a mk2 16v 22mm master cylinder, if you get the correct one for your car then it'll have 6 holes so no need to worry about the pressure switches, or if you do move them you can blank off the unused ports on the mc with later M10x1 bleed nipples (not sure if these would work in the T pieces? probably?)

the mk2 servo/mc is a tried n tested upgrade

Many thanks for all that!  Most helpful!