Is fitting discs always a complete nightmare?

Being properly retro I've never owned a bike with discs before - ridden a few but not owned.

Started trying to fit some on No.1 son's bike:
1 Had to file mount to get calliper far enough outboard to centre on disc on front.
2 Had to file mount on frame to get calliper far enough outboard on rear.
3 Discovered floating rotor rivets foul the calliper...new rotors required.

I also discovered that 1999 Manitous had a rare post mount spacing, used otherwise only by early Giants.
My brakes are 98 Magura Louises (but fortunately apparently not the ones with non-standard IS type spacing).

Is this kind of hassle normal?

No.

I swap and change between all the bikes fairly freely. Once i upgrade the brakes on either mine or my wifes race bikes, the rest gets trickled down.
Can fit, fettle, bleed and ready to go (from a brand new set) in about an hour. Including bedding in the pads and a couple of cups of tea.

Only issue we've had is the new hope floating rotors catch on the adaptor and the very very edge of the front caliper on the wifes bike, took a whole extra 3 minutes to file it flat and i'll probably get a splash of paint on it when i can be bothered. It's a known issue and just a combination of particular design features and tolerances.

And if you've filed the mounting face, i hope you've got it straight. Twisted calipers lead to all sorts of issues. Starting with noise, ending with poor braking, potential for seized pistons and horrendous vibrations straight up through the frame!

I was pretty careful - I'm an engineer so no crazy hacking with an unguided file. As it was a mating face I was doubly careful. The main thing I did was remove the paint surface.

I have had a problem fitting these early louises in the past paricularly to some Marzocchis and also resorted to a file to make them fit. I am actually glad to learn that it is not just me having this problem.

Had some simple ones and some utter nightmares, the latter usually when mixing brands or eras. Hope floaters don't fit through Avid Juicys, for example...

Glad you've got there in the end at least!

Re:

i think thats why many brakes are now post mount, using an adaptor to go to IS frame mounts, it gives you the left right adjustment you need. my rear needed thin washers to get the caliper centered right on an IS caliper. i havnt personally had many issues yet though.

Only issue i've had is rivets on hope saw rotors and formula r1 callipers, all other bikes went swimmingly.

Thanks chaps for the shoulders to cry on!

Re:

No worries , i think we all have something we dont get on with when building/fixing/replacing.
i HATE doing chainrings. dunno why ? just dont get on with em !

I know why - it's because of the inevitable moment when that poxy little Shimano tool slips and you take all the skin off your knuckles. Again.