trex700n gear question

[rcflier1]

it looks like I have the orignal gear set with the 150 tooth auto gear [700n se]. I was going to order a spare set but it looks to not be available.,if I order the upgrade set, does that change the ratio for the better, or will it stay the same?. any more work for the engine?

[Rob43]

Newer gears for 700N (V2?) are 8.0:1. 14 pinion shaft, 112 main if they are the same as the last set I bought last season. I guess, whether or not for the better is up to you. I think they are ideal in my case, with YS91SRX, and target speed 2100. Puts my engine right in the best range for power.

Pinion: HN7037A
Main: H70G002XX

[dchekas]

This depends on the auto gears you order.

Align originally released the White Mod .7 gears with the 700N.

Later, a set of Mod 1.0 white straight tooth gears were released. These were the same ratio as the Mod .7 gears.

Later still (In 2012), Align released an upgraded tail ratio set for the 700N. This features white helical gears that changed the gear ratio from 4.33 to 4.95. This improved tail performance tremendously.

Finally, Align released the black version of the helical gears. These are stronger, but the same ratio as the white helical gears.

The speed up gears greatly improve tail authority with 105mm tail blades. This is especially noticeable if you do tail demanding 3D maneuvers (Very aggressive funnels/Aileron loops, piro funnel, etc), as the 4.33 ratio with 105mm tail blades would blow out if pushed too hard. Many, including myself, ran 115mm tail blades with the old ratio just to improve the tail authority.

That being said, if you upgrade to the new gear ratio, I recommend upgrading to the non-stepped tail shaft. The higher ratio puts considerably more stress on the tail shaft, and with the stepped tail shaft, it may snap off because of this.

Unfortunately, upgrading the tail shaft requires upgrading the tail pitch lever assembly and tail blade grips as well, since the shaft is slightly longer. This was done because the pitch slider housing width was increased for the new tail pitch lever assembly.

This is the parts list for the new ratio with the recommended parts above:

H70G007XX (MOD 1.0 Helical 104T Auto Gear)
HN7042A (Black Non-Stepped Tail Shaft Set)
H70T001XX (V2 Tail Blade Grips w/ larger tail hub for non-stepped tail shaft)
H70097 (New Tail Pitch Slider Assy)
H7NG001AX (21T MOD 1.0 Helical Front TT Gear Set)

[rcflier1]

perfect, thanks