18T Front Trans Mushroom Gear worn out

[Chris Sexton]

When I crashed the only gear that broke was the 54T spur.

I wrapped my tail around a tree. Only gear that stripped was the spur too. Stripped every tooth.


Sent from my iPad using Tapatalk HD

[Jean-Luc Bolduc]

I have 120 flights on my TT between E6 and E7 and doing lots of tic tocs and most piros against torque and my gears look like new, so there has to some other reason this is happening to you. Most likely it's mesh that was too loose or too tight and melted or softened up with friction heat. Put new gears and inspect mesh very closely before bolting cage back in frames.

[benben]

how do you adjust the mesh?

[Chris McVey]

Here is a general example from youtube on how to set proper gear mesh. How to set gear mesh clearance

This is not my video, just something I search for.


Thanks,
Chris

[stevehof]

I don't think you can adjust the mesh on the gears on the torque tube front transmission.

[Tommy Wagner]

Just a thought:

Look where the pins go sit in the gear and make sure that there is nothing in there and that the gear is as far down (or up) as it can go if there is something keeping either one from being all the way on the mesh will be tight.

[Jean-Luc Bolduc]

If the back gears are not showing signs of wear, then that would be a clue that there is a mesh problem of some sort on the front ones. They are close to the same tooth count and size. Possibly your torque tube is pushing against the horizontal bevel gear and tightening it's mesh too much. The TT should slide in all the way and retracted 1 or 2 mm to avoid pushing on the gear while at speed. Same thing for the back transmission. Worth checking.

[Matt Botos]

This is definitely not normal. It looks like a heat/mesh related issue. Production gears on my helicopter have hundreds of flights with very little signs of wear. I would check to make sure your TT is not applying pressure to the output mushroom gear. Make sure your boom is not riding against the bearing block. A TT that is pushing on the mushroom gear will change the mesh of the two bevel gears.

Thanks,

Matt

[benben]

I just changed both of the front trans gears and after two flights the 18T mushroom gear is showing signs of wear again and with lots of black dust. I did pull back the boom a little this time.

[Matt Botos]

Is the front transmission smooth outside of the helicopter? A little bit of dust on break in is normal. The gears in your pictures look melted.

Thanks,

Matt

[benben]

Not silky smooth when new and out of the heli. The gear I posted is not melted just worn with lots of black dust. My boom was flush with the front boom clamp when I first installed the TT kit and now I've pulled back the boom about 2mm.
When I installed the new gear, there were almost no play between both of the front gears but after 2 flights the mesh became quite big. I am waiting for my third front gear to arrive.

[Matt Botos]

Ben,

My suggestion would be to remove the front transmission, disassemble everything, and start from scratch.
Make sure the mushroom gear is pressed completely into the bearings and bearings are fully seated in the bearing block.
Try leaving the bolts slightly loose and checking the gear mesh. Slowly tighten everything down to see if the gear mesh becomes too tight.
Make sure transmission parts are all present per the online manual.
Make certain transmission is smooth before reinstalling into the helicopter.
Gears should have very little lash when they are brand new.

Matt

[Bill Martin]

May be a torque tube bearing is out of the housing.

[Pete Busch]

When I took my front tranny apart to loctite it and put it back together I found you can get the two carbon fiber plates out of square which will cause the two bevel gears to have a tight notchy mesh. All you have to do is hold it square on your table and tighten up all the screws little by little making sure the mesh is smooth.