Hey everyone so thought I might do a guide on how to do a rear drum to discs brake conversion on a mk6 fiesta. Rear disc brakes are fitted on the ST and thankfully it's a straight swap without having to fiddle around with anything. Sadly I can't go into proper detail but I have a lot of pictures which may help give a view on it.
The parts you need for the conversion are: hubs, splash shields, calipers and carriers, discs and pads, hoses which go to the calipers and handbrake cable. Also some brake fluid.
I bought a second hand rear ST 150 beam with everything on it for £100. I found its cheaper to get the beam with everything on it than to buy the things separately. I removed everything off the beam and the Abs wire which is connected to the drums of my car can connect to the discs so you don't have to change those over. I bought a brand new handbrake cable and hoses just so I have piece of mind it won't break in the future.
I'd recommend to spray the calipers in your chosen colour first before installing them whilst they are not on the car. I went for gloss black. I also did the splash shields.
From there you can remove the handbrake cable and the suspension springs from under the car. If your not going to use the old cable again you can just cut it from the drum. Put the handbrake down also as it would make it easier when putting the new one on. I removed the cover over the handbrake lever. You can put the new cable in.
Use an angle grinder or wire brush to remove the rust on the axle to make it smooth before putting the hubs and splash shields on.
Then put on the discs, carriers and pads and the calipers. These are tightened to 60nm. You can then connect the hoses, abs cable and handbrake cable. Do take care when removing the old hose so you try to prevent dirt from going into the pipes which hold the brake fluid.
Put everything back together and bleed out the brakes. From there you can spin each wheel whilst it's still jacked up and apply the brakes to see if they stop. And from there your done.
Before and after