Probably a dumb Q but:
If I wanted to change my 8 speed Campag set up to a 9 or ten speed is it possible to simply change the rear mech and shifters?
Sounds to easy…
Thanks in advance.
AF
Couple of things to be mindful of:
9sp & 10sp chains are required for (respectively) 9 & 10sp cassettes - the chains are (respectively) narrower than 8sp, so a 9sp or 10sp chain won’t like running on your 8sp chainrings - new rings and chain required
Later 10sp RDs & FDs (the “Quick Shift” series) have a lighter spring rating in their respective parallelograms than earlier 10sp and the QS Shifters have a lighter/shorter throw - they don’t work so great with earlier 10sp, so better not to mix 'n match;
10sp Chorus and Record use 102mm bottom brackets, with cranksets and FDs to suit (all for a narrow Q-factor)
Genuine 9sp cassettes are hard to find, although you can do the Miche thing as discussed previously; You can still get decent 10sp cassettes easily enough.
You’ll need wheels with the appropriate freehubs, of course
You might do better by scouting around for a complete 10sp groupset in decent nick.
What CC said, plus a new rear wheel/hub/cassette
Not always, I’ve run plenty of 9 speed chains on 6/7/8 speed cranks without issue. 10 speed chains are more likely to cause problems with older cranks but sometimes it can work. Try it first before you wholesale change everything over.
…but sometimes.
(edit: should have added a :D, don’t want to tick the old boy off 
)
You could say anything and I’d still love you
Yes, It’s a sometimes/not always thing.