Odd whine

[zepherreload]

Hi all i have a problem and was wondering if someone can help me out, i re shimmed my gearbox and followed a tutorial everything went well apart from when i spin my gears the bevel gear makes an odd sound and the gears will stop without it it spins for some time.

 

[Hangtight]

Sounds like a bit of slop in the bushes. If you're spinning the gears from the sector then the bevel gear is spinning pretty fast, and it'll hit a resonance and 'chatter' because the slop in the bushes allows it to rattle around. Try shimming the bevel a touch loose (take a thin shim out from the bottom /AR latch side) and see if that helps, but it's unlikely to be any real problem once the gear train is being driven from the motor pinion. Check that the bushes haven't spun in the gearbox shell and opened out the holes. They should snap into place with no movement.

If they are G&G bronze bushes they'll have worn out in under a year, in which case get some decent steel ones and epoxy them in place.

 

[zepherreload]

Hi thanks for the response i should have said i have new bushings and JB welded them in place so no movement, there is a little amount of movement in the bevel gear  (up and down) there is a 0.1mm shim on the latch side as the motor fits perfect with it. There is no grease on the gears would it help greasing the axles to help stop them wobbling.   

 

[Hangtight]

Is there no shim under the bevel side of the gear?

 

[zepherreload]

yes a 0.2mm shim i checked the motor height with the bevel gear. 

 

[Hangtight]

As long as the pinion is fully engaged with the bevel you should be fine.

Is annoying when you know you've got it nice and you want the satisfaction of watching the gears spin for ages, then all it does is give that funny little squeal and clatter to a halt!

 

[zepherreload]

Hahahaha true with the sector gear and the spur gear it spins for about 8 rotations with the bevel in place if i spin it slow it will spin for about 3-4 at most but still i could just be wanting perfection lol. I have greased it up put it back together and tested it works fine even tho the 7.4 lipo seems to be draining a little fast with the m120 spring about 2% every 3-4 shots

Edit after firing a few shots with BBS the % didn't drop that much odd but seems to be working.

Thanks for the help.

 

[Sitting Duck]

That squeal you sometimes hear is a dry spur or bevel squealing when you spin test the gears...

(bevel gear spins 4 to 7 times to every sector gear rotation - so the bevel is going nutz so to speak)

(Common squeal you hear on a bone dry all bushing build)

On the final or near final spin test then apply a little lube - ooh ergh missus....

You don't want to coat the gear axles with grease coz it will slow the gears spinning during testing

apply a smidge of grease & wipe off excess or if you have some silicone oil - that will shut it up.

Nice quiet as possible smooth running gears - job done

rebuild box & grease the gears properly on reassembly

fingers crossed she sounds decent when you test her

& not like a dying cat being stung to death inside a big tin of wasps/bees