Punchy Dan:
:shock: I agree with Bking
You shouldn’t, massive improvement in stopping distances with discs. Drums are old technology and should be banned for anything but off tarmac work and even then I’m not keen. I don’t see where the bother is with working on them.
Main reason they’re still so prevalent is trailer manufacturers get drum axles much cheaper so they push them. Spring parking brake can sometimes be a problem if you present trailers for test loaded but fine empty which is how most people test them. Also with discs brake test efficiency is more consistent across different load weights where drums are more prone to pass on locks empty and be dire laden.