View Full Version : E720 pinion on a scorpion motor
01-06-2012, 11:38 PM
So I got a 4035 450kv to go with my heli. Looks like there's a bit of a problem though...
On the scorpion motor there's a tapered shoulder on the shaft where it comes out of the motor, and a snap ring to hold everything in place. As a result, the pinion can not sit right against the bearing, and when it's installed in the heli, the grub screw binds up in the main gear.
The pinion is clearly supposed to sit closer to the motor, but due to that shoulder, it won't go any closer. So it looks like I'm going to have to grind down the ID of the pinion on the motor side to get things to sit right.
That is unless anyone has any other ideas? Sadly I don't have a metal lathe to turn down the shoulder on the motor shaft, so that's out.
I think I'll probably document (with pics) this issue and my attempts at solving it for the next guy that finds this happy surprise :)
01-07-2012, 09:03 PM
Just mount your pinion up side down and use the low counter bearing block location given that your motor has long enough shaft. Don't grind the pinion.... Learn that from Gary.W
01-07-2012, 10:07 PM
I'll try it, but the flat on the motor shaft doesn't go all the way to the end of the shaft. May not have a flat spot to put the grub screw into if I do that. Good idea though.. We'll see how that works.
01-08-2012, 10:32 PM
As I suspected, the flat is only near the base of the shaft. I don't think it's a hot idea to set it on the rounded part of the shaft, so I'm back to plan A it looks like.
Whenever I get time I'll take pics along the way to show what the problem/solution I go with is. That is of course assuming I don't totally botch it up.
01-12-2012, 06:27 AM
I run the pinion with the grubscrew on the bottom, but the hacker motor shaft is flat all the way to the end. The turnado also has the tapered portion you mention, as the shaft is really 8mm, with the external part turned down to 6mm. I would suggest grinding a flat near the end of the shaft and flipping the pinion over. This needs a shaft of I think 38mm from the face of the motor. The hacker turnado's originally came with a shaft of that length and mine are that long so it works perfectly. As a side-note, at some point hacker shortened the shafts, but I think aero-model has the longer shafts for anyone who is running a hacker and the stock shaft is to short for this machine. I've seen shorter shafts used, with the setscrews up top as intended, but there isn't much engagement in the support bearing.
01-12-2012, 09:50 AM
Yeah, the shaft on the scorpion is plenty long, so I could put the bearing block in the lower position on the frame, and still have the motor shaft completely supported.
I still haven't had time to do anything with this, so I'm still mulling over exactly what to do. I had thought that boring out the pinions was a decent idea to start with, but the more I think about it, filing a flat on the motor shaft probably is the better way to go. That way those pinions can still be used on another motor should I decide I want more power on down the road.
Now I just gotta come up with a decent way of getting that extra flat on the motor shaft. Hand filing is an option I guess and will probably have the cleanest result, but I expect it's going to take a while to get through that much material.
Any suggestions are welcome! And thanks for the input Gary. Appreciate it.
01-12-2012, 01:36 PM
Hand filing.. You must have too much time in your hand! :) Use a Dremel and a enforced cutting wheel to grind a flat spot on the shaft.
here is the flat spot for dummy video ;)
01-12-2012, 01:39 PM
Maybe a combination of the two then. Using a dremel alone will make a bit of a hack job out of it I think.
01-21-2012, 08:16 PM
I'm running a 4035 500KV and had the same problem. I simply installed the motor plate in upside down to move the whole motor up slightly. the only catch is you have to play with the mounting for the tail rod guide so that the rod doesn't scrape along the frame support just ahead of the motor. I still had enough length on the motor shaft to secure it in both blocks. Should work great for you.
01-21-2012, 08:18 PM
Sorry that last reply was from memory. The frame support you have to watch out for is right behind the motor mounting plate.
01-21-2012, 09:20 PM
Hey another good idea. Actually, I already filed another flat on the motor shaft. Actually I was able to do a pretty decent job with just the dremel, so no need to go buy a file.
Thanks for the suggestions all.
08-21-2012, 09:02 AM
Do you like the 4035-450 in the G4?
08-21-2012, 02:44 PM
Yep.. It's got gobs of power - probably way more than I need so I'm pretty glad I went that route instead of the 10 000w peak ridiculous motor I originally had my eye on.
It also leaves you with more reasonable gearing options being 450kv rather than the 520kv.
Currently I'm running 2100rpms - more than necessary, and the only time it bogs at all is if I jam full collective and cyclic at once (ie: Tic tocs got too low, and now I'm panicking to get the hell out of dodge). Other than that I can reef the sticks around like crazy and it holds up just fine.
That said, I'm not a smack guy either. So if you like the ridiculous fast direction changes and hard stops, then the 10 000w 4025 might be the way to go.
I'm very happy with what I have. This heli flies fantastic.