my hbk2 brushless flys pretty good with tail belt mods and trex t/r blades...i have a set of hardened spindles which i haven't used yet...fwiw, on another forum, dr. roo (who posted a very nice mild 3d vid taken by his wife) gave some tips for using the trex spindle on the stock hbk2 head...i bought the parts from heliproz, but haven't tried them yet...fwiw, here's the info:
HBK2 Spindle Mod (Dr Roo)
http://www.rcgroups.com/forums/showt...o+ring+spindle
Product Code: HS1003 Name: Feathering Shaft HS1003
Main Category: Helicopter Parts Sub Category: T-Rex 450S Parts Option Price: AUD$8.00 Package Weight: 20 g
●Feathering Shaft X 3
Product Code: HS1186 Name: O-Ring HS1186
Main Category: Helicopter Parts Sub Category: T-Rex 450S Parts Option Price: AUD$2.80 Package Weight: 20 g
Specification:
●O-Ring (Φ3XΦ6.5X2mm) x 4
Product Code: HS1195 Name: Main Blade Screws HS1195
Main Category: Helicopter Parts Sub Category: T-Rex 450S Parts Option Price: AUD$2.80 Package Weight: 20 g
Specification:
●Stainless steel socket screw (M3x14mm) x 2
●Nut (M3) x 2
●Socket screw (M2x5mm) x 2
Yes, simple swap. Doesn't require any other modification, and will stiffen up the head really well, so you get a much more positive response -- Makes the King feel less "mushy".
Spindle:
http://www.wattsuprc.com.au/product....asp?pid=HS1003
O-rings:
http://www.wattsuprc.com.au/product....asp?pid=HS1186
Socket head bolts:
http://www.wattsuprc.com.au/product....asp?pid=HS1195
You need the bolts that go in the spindle, which are the smaller black ones in this set. Basically, you just need to get 2 M2x5mm bolts. Remember the Loctite when you install them.
So, take out stock ESky spindle and replace with Rex spindle, put all the washers, etc., back as you would an ESky spindle except instead of 1 O-ring per side you want 2 O-rings per side.
It's that easy. You need 2 O-rings as the Rex spindle is just a bit longer than stock but as it's not 2 O-rings longer than stock it has the effect of making the head just a bit stiffer. Plus, you don't have to mess with the nuts of the ESky spindle and the Rex spindles are stronger as well.