Trex700n DFC vs older versions

[rjay]

Hi guys

I am considering buying a Trex 700n, I am aiming at the second hand market. Problem is most of the guys advertise their 700n as "Trex 700N DFC", but with closer inspection it’s an older model that has the DFC head.

Furthermore I had a quick look on the internet but could not find a quick breakdown of how the 700n was upgraded since introduced. Seems like the new DFC has a thinner frame and the canopy looks different (not sure if it will fit the older models without having to re-align the holes.)

Could anyone please share the difference between the newer DFC and the older Pro models? I came across ads of people selling the Limited Edition (flybar version converted to FBL)

Would it still be worth my while going for an older Pro version?

Buying new would obviously be first prize, but with the weak currency it becomes rather expensive for the combo. I have a set of HV servos and MSBrain gyro I want to install, so no need for the combo. There is some nice second hand deals available on the local forums here in South Africa.

Thank you!

[mqowen]

Originally Posted by rjay

Hi guys

I am considering buying a Trex 700n, I am aiming at the second hand market. Problem is most of the guys advertise their 700n as "Trex 700N DFC", but with closer inspection it’s an older model that has the DFC head.

Furthermore I had a quick look on the internet but could not find a quick breakdown of how the 700n was upgraded since introduced. Seems like the new DFC has a thinner frame and the canopy looks different (not sure if it will fit the older models without having to re-align the holes.)

Could anyone please share the difference between the newer DFC and the older Pro models? I came across ads of people selling the Limited Edition (flybar version converted to FBL)

Would it still be worth my while going for an older Pro version?

Buying new would obviously be first prize, but with the weak currency it becomes rather expensive for the combo. I have a set of HV servos and MSBrain gyro I want to install, so no need for the combo. There is some nice second hand deals available on the local forums here in South Africa.

Thank you!

I wouldn't hesitate about a second hand older style airframe. They are proven to be good heli. As long as you are ok with second hand and the possible things you might find even with a seller of good faith. Seems like most used things I buy end up having something that needs to be replaced. and something the seller may moto be aware of.

But the older style TREX with follower flys just fine. No problems at all. I don't own TRex but I am around guys who do and I have test flown them.

Engines are a different story. Personally I would prefer a new engine. But even then, for the right price might be worth a shot especially if it's already broken in and tuned.

[dchekas]

The new 700N DFC has the following changes/features over the prior 700N LE 3GX:

-New main gear ratio (8.0:1 instead of the previous 8.2:1) with helical gears
-Includes new tail gear gear ratio (4.95:1 instead of the previous 4.33:1)
-Narrower frame
-Larger fuel tank
-Includes longer boom/TT/Carbon pushrod for use with up to 720mm blades (You can use standard boom/TT/carbon push rod with it as well)
-New style engine mount
-Includes DFC rotorhead/swashplate
-New tail pitch slider Assy/updated tail rotor case
-New Canopy

They are both good models, and there is certainly nothing wrong with using the older 700N LE/Pro models (I still fly mine). They can be updated with the improved parts Align has come out with just the same as the newer DFC model.

I would look for a Limited Edition model if considering going used, ideally one that was bought new in 2011 or later. These should include the majority of the final tweaks Align made to the 700N, including the FBL bell cranks and deeper socket frame bolts.

[Baedarlboo]

Another thing to consider, the older model frames have much more aftermarket parts available than the newer DFC frame. A lot of mechanical parts will interchange, but the newer DFC frame design went with a narrower frame so all the aftermarket parts designed for the older frame set will not cross over.to the new frame.

[banditpowdercoat]

Can one up the tail speed on a pro with the dfc gears? I run KBDD tails and would like a little more tail speed

[dchekas]

Yes.

You will need either HN7125 or H70G007XX and H7NG001AX.

[banditpowdercoat]

Ohh ok. Just the m1 autorotation gear etc? I got that so I guess I already am the fast tail speed

[marc8090]

Not quite that simple. Having mod 1 gears does not guarantee you have the fast tail ratio. And just a suggestion, do a search first as I have posted this before. The mod 1 autorotation (bottom) gear is 104 teeth, either straight cut or helical. Both have been made white and black. The front torque tube (non bevel) gear is available 24 tooth (straight), or 22 and 21 tooth (helical). 24t gives you 4.33 to 1, 22t 4.73 to 1, and 21t 4.95 to 1. That being said, while many people are using the 4.95 ratio successfully on a nitro, I suggest you read the 80 something page thread in the 700 electric forum titled something like "Trex 700 tail hum".

[banditpowdercoat]

Ohh ok. Ya. Searching doesn't work well on my phone with tapatalk. But I'm running the 24 tooth. Have to read up on how they are setting mesh with smaller gear. Not keen on slotting frame etc. I wrench enough on her. I wana flt