Update:
I figured it was time for an update, since it has been a while, anyway, been working on my custom Hot Rod strat for a couple of weeks now, and I think I have finally cracked it, no I didn't put a big crack in the body, I think I have finally got it nailed, firstly, I think I have finally got a set of pickups in it that actually work well together, and secondly I think I have finally got it to stay in tune, yes for once it does stay in tune like it's supposed to, I think a lot of trouble getting it to stay in tune was due to the bridge posts I was using, recently I bought a Gotoh Floyd Rose bridge and wasn't happy with it's performance, so I left it alone for some time, a couple of nights ago I decided to try using the two bridge posts that came with the Gotoh Floyd bridge in my Hot rod Strat, then I swapped out the stock string-saddles on my chrome Schaller Lockmeister Floyd for the ones on the Gotoh Floyd, they fitted fine, next I fitted my chrome Schaller R3 locking-nut to the neck, I had to remove the small piece of rosewood I had glued to the nut shelf in order to get the Schaller locking nut to sit at the correct height with a couple of shims underneath it, I also installed the INF4 bridge humbucker from my white Ibanez RG350DXZ, the RG350DXZ guitar turned out to be junk, but the pickups were all still go.
So, I went to the Pro Music shop here in Darwin to buy some more strings and bought a 3 pack of DÁddario 42-09 gauge strings (my usual gauge for strat style guitars), and proceeded to give my Hot Rod strat a good setup after installing the new strings, after playing the Hot Rod strat through my Marshall amp for a couple of hours, or so it seemed, I was a happy chappy, the guitar really sounds like it has come alive, it sounds big and fat, but still has the Strat sound, the pickups all seem to work much better now that I have the INF4 humbucker installed in the bridge position, and yes it is even staying in tune now, I only had to tweak one of the fine tuners a small amount, nowhere near as much tweaking as I had to do before, it even does the gargle effect if I flick the trem arm, I also realized that I was going about the process of tuning-up a Floyd equipped guitar all wrong too, you tune the guitar as close to in-tune as you can get it, once that's done you put the string-locks on, but don't do them up too tight, after that you simply use the fine-tuners to fine-tune the guitar's tuning and that's it, so consider myself re-educated.
I'll post some more pics of the Hot Rod strat later on, so stay tuned.....(pun fully intended).
What I will say is this, the tuning-stability, and performance of any double-locking Floyd-style trem system is heavily dependent on the condition of the knife-edges of the bridge, and the V-notches in the bridge-posts, if either, or, both, are worn, then the trem system is going to have a lot of trouble keeping the guitar in tune, the condition of the locking nut also has a bearing on how well the system performs too, if it is worn or moves, or causes the strings to slip out of tune, then the system isn't going to perform as well as it should.
Here we go, some new pics of the Hot Rod strat, she's all set up with a set of DAddario 42-09 gauge strings:
I just tried doing some dive-bombs, pull-ups, and pinch-harmonics as well as some general whammy-abuse and it still stays in tune.
Check out how low I managed to get the action at the 17th fret in the bottom pic, it's about 2mm.