Fresh Mostro Build - Couple Issues

[DCflyer]

Recently built up a Mostro. Not sure how much insight I will get on this forum since its pretty slow here but here goes.

This was some of the first test spools of this machine. You can hear in the video a very obvious clicking sound coming from the gearbox. I am running a motor counter support bearing on this machine - pinion is not touching anything. Motor belt is nice and tight. HW ESC timing at 18 degrees and PWM at 8khz. One way pulley has been greased. Pinion is set well. That's one issue.

Another issue is some of the temperatures i'm seeing. The most concerning being the motor belt and the main gear. In the video you can see the main gear temp is up over 100 degrees and that was at 50% throttle. Later I spun it up to 80% for about 20 seconds and the main gear was at 120 degrees. The aluminum pinion was HOT!

The hottest part of the gearbox is definitely the pinion, followed by the main gear and motor belt / motor. This leads me to believe there's something with the pinion...........anyone else experience this for their first runs? Can anyone tell me what gearbox temps you were seeing when you first put together your machine? Also, could anyone put a temp gun to their main gear, pinion, and motor belt and tell me what you're seeing now after about 1 min of running (and at what RPM)? That would be awesome.....

I have a Goblin as well with steel pinion and the gearbox is always 50-60 degrees.

What is going on here? I can't adjust the pinion lash here. I can apply Dryfluid to the main gear and see what that does.

Should I just run it and hope the gear box breaks in a little more? Everything is really really tight right now, but when I turn the motor by hand it all feels very smooth.

Also, any idea what this clicking noise might be? In some of the Mostro videos i've watched, i've actually heard this clicking-like frequency noise before. Goblins have it as well on spool up and pool down. Its less obvious at higher RPM's.

Any feedback is appreciated.

Mostro Test (1 min 55 sec)

Gearbox clicking noise example (This is not my machine):

You can definitely hear what i'm describing around 10:55min in this video.

Avant Mostro 700E DFC Kit Review - Part 1, Intro and Flight (12 min 57 sec)

[fatboyrob]

my mostro made a clicking noise that turned out tho be the tail belt tensioner bearings. the tail gear box also made a clicking noise but i just did the mod that is on this site and that went as well.

[john5785]

I have a bunch of mostros...and I would say that sounds pretty typical. On the main gear...avant said the mesh was intentionally to tight and it would wear in. I've put them in hard with power and have yet to need a new main gear...basically wouldn't worry about it. I agree that the clicks are most likely a bearing. Make sure the belts aren't to tight and send it! They fly great!

[DCflyer]

Thanks for the feedback. I tried the machine on 7S just now and it sounds much better. Going to apply some wax lube to the gear tonight and do another 4/5 test spools and heat cycles to break the gearbox in some more. Hopefully the lash will loosen up a bit like it did on my Goblin.

Will see what the motor/gearbox/clicking sound does after that. If it gets worse i'll probably have to address it. Hopefully it will wear in. Hate to pull this thing apart.

[FBLessOne]

That sounds like an excessively tight motor belt. You have a motor bottom bearing block that's not standard in the kit nor an avant part so I assume that because of it you're probably thinking that it's safe to over-tighten the belt but the extra tension just creates issues in the large pulley's bearings that are under excessive side load. The pinion and main gear require either silicon lubricant or even better Teflon Silicone Spray that dries and leaves a Teflon coat. This lowered the temperature in my case around 50 degrees. Use the same Teflon lubricant on the inside of all the belts and coat their pulleys too. It makes the whole heli run very smooth. Interestingly enough lubricating the belt also lowered the temperature of my motors because the heat that dry unlubricated belts produce are transferred to the motor via the motor shaft. I have three electric and two nitro mostros and the nitro ones because of the oils from the exhaust keep belts lubricated so you get the same effect.

[DCflyer]

Originally Posted by FBLessOne

That sounds like an excessively tight motor belt. You have a motor bottom bearing block that's not standard in the kit nor an avant part so I assume that because of it you're probably thinking that it's safe to over-tighten the belt but the extra tension just creates issues in the large pulley's bearings that are under excessive side load. The pinion and main gear require either silicon lubricant or even better Teflon Silicone Spray that dries and leaves a Teflon coat. This lowered the temperature in my case around 50 degrees. Use the same Teflon lubricant on the inside of all the belts and coat their pulleys too. It makes the whole heli run very smooth. Interestingly enough lubricating the belt also lowered the temperature of my motors because the heat that dry unlubricated belts produce are transferred to the motor via the motor shaft. I have three electric and two nitro mostros and the nitro ones because of the oils from the exhaust keep belts lubricated so you get the same effect.

Thanks for the tips. I coated the main gear and pinion with White Lightning dry wax lube last night and a applied several coats of CRC rubber safe silicone lube to the main drive belt and tail belt. Gearbox definitely spins much smoother now.

I'll release motor belt tension tonight and do some more test spools to see what happens. My motor belt is tight but not excessively so - there is 2-3mm of deflection in the belt when I push into it with a wrench.

I set it the same i've set my Goblin's motor belt tension as per Bert K's video suggesting that belt needs to be really tight if you're running high headspeeds, which I intend on doing with this machine (14S, 2250rpm).

[FBLessOne]

Originally Posted by DCflyer

Thanks for the tips. I coated the main gear and pinion with White Lightning dry wax lube last night and a applied several coats of CRC rubber safe silicone lube to the main drive belt and tail belt. Gearbox definitely spins much smoother now.

I'll release motor belt tension tonight and do some more test spools to see what happens. My motor belt is tight but not excessively so - there is 2-3mm of deflection in the belt when I push into it with a wrench.

I set it the same i've set my Goblin's motor belt tension as per Bert K's video suggesting that belt needs to be really tight if you're running high headspeeds, which I intend on doing with this machine (14S, 2250rpm).

I'm not familiar with that lube but it seems to be for bicycles. I would think that any wax-based lube would be affected by he heat. If I were you I would keep an eye on it. Other than that let us know how it turns out.

[DCflyer]

Originally Posted by FBLessOne

I'm not familiar with that lube but it seems to be for bicycles. I would think that any wax-based lube would be affected by he heat. If I were you I would keep an eye on it. Other than that let us know how it turns out.

I picked up some of the Teflon lube you suggested. The wax lube is quite thick and flakes off in fairly quick order. I usually use it for break in (first dozen or so flights) and then apply DryFluids, but if you say you are seeing that massive of a temp decrease with the Teflon stuff i'll definitely try it out.

Finished the airframe last night by mounting the head and tail assemblies and loctiting all remaining screws and installing the tail control rod.

All that's left is FBL setup. I plan on getting the machine in the air this Sunday if the rain stays away. Hope to get a couple flights on it at 1950rpm and see how it sounds in the air.

I plan to post a build thread on it. Only component i'm still waiting on is an R2 Prototyping supercapacitor buffer unit.

[gilligansc]

I agree that the main drive belt does not have to be super tight. What carrier bearing is that.I have never seen one on a Mostro.
Another thing to look at...I could not tell from the video.
If the main drive belt is riding a little low one the main pulley, it can rub on the tail belt where they cross. The pinion height is critical for the belt to ride on the pulley in the perfect spot. You should see a tiny part of the pulley showing under the belt.
Hope this helps.
G

[DCflyer]

Originally Posted by gilligansc

I agree that the main drive belt does not have to be super tight. What carrier bearing is that.I have never seen one on a Mostro.
Another thing to look at...I could not tell from the video.
If the main drive belt is riding a little low one the main pulley, it can rub on the tail belt where they cross. The pinion height is critical for the belt to ride on the pulley in the perfect spot. You should see a tiny part of the pulley showing under the belt.
Hope this helps.
G

Thanks. Yea, i've adjusted the motor pulley several times now so that the main belt is rotating on the main pulley correctly. I just see a little bit of metal at the top and the bottom.

The counter-bearing support is from a Synergy E7 SE. After doing a bit of research I found out that it uses a 6mm bearing and is 62mm in width. The Mostro frames are 60mm in width so you have to take out 1mm on each side and it drops right in.