Binding front TT drive gear

[navigator2011]

Hi guys, I am putting together a 250 DFC with the TT, and I am running into a weird problem where the front TT drive gear binds with the main gear and gets "grindy" once I tighten the frame down. Everything seems fairly smooth and meshes well until I tighten things up. It's almost like Align designed the front TT drive gear just slightly too close to the main gear, and so the mesh is too tight.

When I install a belt drive gear onto the bird, however, it's butter smooth, and the mesh is seemingly perfect with nearly zero drag.

I am just wondering if anyone here encountered this problem with the TT gears, and if so what did you do to fix the problem. I am stumped.

[navigator2011]

Well, in absence of any advice, I suppose I'll give a new front TT gear box a try. If that one also gives me trouble, I guess I'll have to do the belt conversion.

[Toocool4]

You must just have a dud set. I have never had a problem with umbrella gear mesh.
Hopefully a new set will work for you.

[navigator2011]

I hope you're right, this has stalled my whole project. The umbrella gears seem to mesh with each other just fine. It's the mesh between the main gear and the lower drive gear that is the problem. I did a whole lot of searching for anyone else that's solved this, and I didn't find much. Seems like the gears are perfectly smooth for most people, which led me to think maybe a new gear box would solve the problem. In any case, I hope I can successfully run the stock TT tail set up for at least a while before sinking even more money into this bird for a belt conversion.

[Toocool4]

Hopefully the new gearbox will fix your issues. I would not goto belt as I love the set and forget it of TT.

[navigator2011]

Hi, thanks for your reply. I thought if sort of interesting to find older threads about how to change from a belt to TT. Apparently a few years ago, changing over to TT was the recommended cure for various tail issues. Today, it seems to be quite the opposite.

[Toocool4]

People are just fickled, use whatever comes with your heli why waste money converting.

Both versions work well, belt has the advantage if you are still hitting the tail on the ground.

[navigator2011]

Well, I received the new TT transmission box yesterday--it definitely meshes more smoothly with the main gear than did the original transmission box. Not as smooth as the belt drive gear, but it's definitely smoother than before. Now, there's only a slight bit of "over-meshing" at one point along the circumference of the main gear. Maybe after breaking in, it'll get smoother.