Just finished building my Roban Bell 407 and can't wait to fly. However, I noticed some play on the tail rotor. This is a torque tube and I'm not sure how much play I'm supposed to have on the tail rotor. Is it normal?
Thanks
Ed
Thanks
Ed
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There will be some, yes. “Some” is subjective, however. Too much play leads to vibration and gear wear issues. I recently did a post on this topic addressing my observations and solution to excessive play by shimming the front and rear umbrella gears on the torque tube. The shims are included with your kit. You will see a big improvement, but not a 100% elimination, of that tail blade play. -
Yep, its normal to have some play, I put several flights on both my big Roban 800 Hughes 500 before I shimmed them up, well actually I haven't shimmed the OH-6 Cayuse yet, I was putting more flights on it first to let the factory gears wear in a little then I will shim it again, I did the Magnum PI already, I let the stock gears wear in for a few flights then I just shimmed it a couple of flights ago, I noticed the gears were getting little shiny spots more on the tips of the gears, so in order not to strip a gear I shimmed the tail gear and the front one as well, you want a little backlash on them anyway, but if you notice some huge slop right after your build, you might want to shim them right away, to tight is bad as well, so you just have to kind of guess at it if you need one or two shims, the way I tested mine, I grabbed the the gear with two fingers on each side and pulled and pushed on them back and forth and you can feel the slop, if its to much, just take it out and add a shim or two and test it again, you should have some exra shims in a parts bag??Comment
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Yeah that's the same play I'm talking about, some guys will think it's to much I'm sure but some of that is the fit of the torque tube into each umbrella gear plus you have the four umbrella gears meshed together with a little backlash in those which is needed, so its kind of up to you if you want to try and slip another shim in there to see if it will tighten it up a little if you think it's to much.Originally posted by Kaliman911 View PostComment
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My B407 has that same amount of play, of course. When I catch up with my other projects I plan to pull the B407 mechanics out and test the front and rear torque shaft gears for endplay and shim accordingly. I should have paid attention to that when I built the kit but I have always done things the hard way so it’s too late to change now.
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Lol, I hear you PawPaw. I sometimes do things the same way. Now, I have already spent so much time building and setting up my Bell 407 that I don't want to take apart again and risk breaking something else. It happens every time. I'm gonna leave it as it is and deal with at a later time when it gets broken in a bit more.
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You guys should be okay, just watch for the shiny spots on the gears after a flight or two or it may take more flights to show up, if they look shiny about 1/2 way up each tooth I would think your fine, I noticed on my Magnum PI version after about 20 flights the shiny spots where more on the tips of the gears, so I did shim those on both ends, there are some tiny shims as well for the tail shaft and front tail drive gear but I only did the big umbrella gears on mine, one shim added to the shim thats already installed (2 total) ) on each worked good, it has a little more gear noise right now from being a little more tight but after a few flights already it seems to be getting less, I keep my gears well lubed with honey grease from Amain Hobbies, I guess the car guys use it, its really sticky and comes in a small container for about $7, kind of expensive for such a small container but it don't take much, it's actually way cheaper than buying a new heli if you strip a gear and crash......
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