The Align T-Rex 600 DFC Head currently available is not intended for use on the Nitro T-Rex 600, but only the electric version and the T-Rex 550.
The problem being the supplied main shaft is the wrong length for use on the Nitro model.
Not that I was about to let that deter me 
The correct length shaft can be made by machining down a standard T-Rex 600 nitro main shaft, and drilling a new top bolt hole. The new top bolt hole should be drilled 156.5mm above the bottom bolt bole, measured from hole centres, leaving 10mm of shaft above the new top hole. Thanks to Pete Ayriss for working this out and sharing the information with me, and thanks to Noel Cross for machining the shafts for me!
Here is how I went about fitting and using the DFC head on my T-Rex 600 V2 flybarred nitro model.
Flybar head fitted on the model
First, we take the flybar head off the model, and remove the parts we are no longer going to need.
Flybar head removed
The DFC upgrade kit comes with only the parts required to upgrade the latest versions of the Align heads, so if yours is not a latest version head, with the separate pitch arms on the grips, then you will also need a
new set of blade grips as well. The T-Rex 600 Nitro V2 comes with the new blade grips already.
Parts not needed
The parts we will be keeping from the existing head assembly (everything on the main shaft from the mast locking collar upwards) are the swashplate, feathering spindle (and bolts and spacer shims), blade grips and blade grip bolts. That’s it!
Stuff to keep
Next we need to start building the new DFC head assembly. Here’s a picture of the DFC box.
T-Rex 600 DFC Head Upgrade Box
And here are the box contents.
T-Rex 600 DFC Head Upgrade Box Contents
Make sure you apply grease to the thrust bearings and a little on the dampers when assembling the new head. Here we have a picture of the assembled blade grips and headblock. The DFC downlinks are not yet complete, although I found that threadlocking the metal parts in place (using
green threadlock) and having them screwed all the way in was the best option here.
Head Block and Blade Grips assembled
Next we will be removing the inner swash balls (all four of them) and fitting two shorter balls on opposite sides of the inner swash. This will help increase resolution. This next picture shows the existing swashplate, along with the two new swashplate balls supplied in the DFC kit. We will not be using these two new balls from the DFC kit as they are too long.
The Swashplate
Short links
And here is the completed head assembly ready for fitting to the model.
Complete head assembly
Once the head is fitted to the model, all that’s left to do is fit your chosen flybarless controller (a fullsize VBar in my case) and set it up!
DFC Head fitted to the model
Having flown this a lot since fitting the DFC head, I can tell you it certainly performs well. I have not yet properly crashed the model, but I have seen one that took a tumble and the bolts in the pitch arms will bend. Keep some spares on hand (when they become available!).
As it stands right now, the upgrade process is not straightforward for this specific model (T-Rex 600 Nitro V2), but I’m sure Align will resolve this quickly and make the upgrade process painless once they release a main shaft that doesn’t need to be machined to the right dimensions.
A final note… The dampers wear out pretty quickly, so replace them often to avoid issues with blade tracking in flight.
I will post a video of this model flying in the near future, so watch this space!
