A few pilots have had problems with the end of the tail shaft breaking off. The new upgrade rear tail shaft has no step down on the end (stronger). To do the upgrade you need the V2 tail rotor (All Silver One) with the new hub which has a larger hole diameter for the shaft. Make sure you do not purchase the silver V2 tail rotor that has the hub with the smaller hole as it will not work unless you change the hub. See links below for correct part numbers. The black gears on the rear shaft & umbrella gear have the same amount of teeth as the original white gears just a different type of material. I have done the upgrade and it works great.http://www.aligntrexstore.com/Torqu...2A-_p_2271.htmlhttp://www.aligntrexstore.com/700-M...1XX_p_2273.htmlhttp://www.aligntrexstore.com/700-T...2XX_p_2284.htmlhttp://www.aligntrexstore.com/Torqu...5XX_p_2242.html
I'm not sure if the 700 DFC kit's already have this upgrade or not. Dino can probably talk about that. If your 700 DFC kit does not have this upgrade it would probably be a good idea to do it because the 700 DFC tail rotor turns up higher rpm's due to different gear ratio on the front tail drive gears.