A caliper rebuild would take too much time at the track I think.
Heh, that's what I love about being 19 years old and at the track. All the older people there really love how enthusiastic I am and love talking to me about their experiences. They love that somebody as young as myself is getting into the sport already. It's great because a lot of them use to have these bmws or still race these bmws (especially e36 and e30 m3's).
I learned what I could break by listening to them and then proceeded to upgrade those parts. This is why I don't bother with the engine... it's not the weakest link, it's problay the strongest.
What's wrong with the e30 318iS? It's a wonderful momentum car.