Shimming new gears issue - Is this normal?

[ao_tenshi]

Originally Posted by Azathoth

TO THE OP:L

With the gearbox open, put a 0.2 mm shim on the spur gear (middle one) such that is is on the gear face not on the axle. Use this 0.2mm shim to ensure that their is sufficient space between sector and bevel. 6 shims or 0.6mm is a huge amount.

If you have a pair of digital calipers use the mathematical method to shim the gearbox instead of the 'doing it be feel'.

Thanks for the tip Azathoth. Will try this out.

[ao_tenshi]

After trying the A2, looks like the weak motor was the main issue (aside from further perfecting my shim job).

I have decided to use the A2 on my other gun. So need to get another one for this build. Currently looking at the SHS High Speed OR SHS High Torque.

Does anyone have any recommendations on HT or HS based on my current setup?

SHS 13:1 Gears
M90 (or M100) Spring
AOE/Sorbo done
Running 7.4v Lipo (may upgrade to 11.1v later on)

This gun is my indoor gun, currently around 350-370fps (definitely wont be going above 400fps).

[EOD Steve]

For your application, honestly it won't matter a whole lot. I use the HT by default only because it's just a much more versatile motor if I do want to increase power down the line.
The higher TPA is more efficient per amp but your particular setup won't see that many amps anyway thus inconsequential.

[ao_tenshi]

hey guys, quick question... i find this very strange but I notice ALL of my bearings seem to protrude out of the gearbox by about 1-2mm. This causes hell when shimming as whatever i measure will be compromised by the pistol grip, selector plate etc from the outside of the gearbox.

My question is, does this seem right or is something wrong with this gearbox?
(This is a stock G&P by the way) Should I get new bearings or bushings that will be flush with the exterior wall of the gearbox?

[lurkingknight]

Originally Posted by lurkingknight

check to see if the grip is pinching the bushing/bearing on the bevel. 8 and 9mm gearboxes have more issues with grips but it's not uncommon to see a grip interfering with the bevel gear on any gearbox. You'll see a little pocket in the top of the grip that is supposed to accomodate the gear axle. you may have to dremel that wider/deeper.


Also g&p 120 motor... lol.

2 weeks ago.

[ao_tenshi]

Originally Posted by lurkingknight

2 weeks ago.

Hi lurkingknight,

Yes, I understand this issue was mentioned earlier. I am wondering if this is "normal" or if I am in an one-off case. Reason for my ask is if this is unusual then I would rather get new bearings that are flush with the gearbox. I have modded the pistol grip as mentioned earlier, but unfortunately not able to mod the selector plate.

Hope this makes sense and is not a repeat of the question from two weeks ago.

Thanks again!

[Hectic]

It may be easier to fit a better gearbox shell the bearing thickness may not necessarily be the whole issue, it could be how deep the holes are bored into the gearbox etc. Also a good she'll will last longer and should be easier to shim and assemble.
you could try new bushings but may wind up needing a shell too. If you just grab the shell it'll likely come with the appropriate bushings.
lonex shells are pretty nice.

[ThunderCactus]

sometimes its normal and causes no issue, sometimes it's an issue.
Many mechboxes have the bushings stick out about 0.5mm, easy way to check if it's an issue is 1) you can issues sticking the mechbox into the receiver and 2) install the mechbox with any compression parts and try free spinning the gears. If they bind, there's your problem.

Some mechboxes, like the G&P 249, absolutely require special pancake bearings due to very tight tolerances in the fit between mechbox and receiver

[ao_tenshi]

Hey everyone, just wanted to report back that I have re-shimmed using pinion to bevel, installed new SHS HT motor and everything appears to be running smoothly. Only minor concern now is that the motor seems to heat up quite a bit, but I heard SHS motor run warm by default.

This whole process was a lot of pain but also a very good learning experience for me. I want to thank you all for your guidance and suggestions to help me get through this Cheers!

[Hectic]

Glad you got it sorted out!!
A lot of times with high torque setups (ie running fast gears and heavy springs) combined with a lot of semi shooting will cause a warm/hot grip.
my 16:1 builds normally don't have much heat issues but 13:1 gears and m120 springs tend to heat up motors pretty good after 5 or 10 shots in semi quickly. Dump full mid caps in auto without heat issues tho.

[ThunderCactus]

motors get hot, it's what they do. As long as it's not chewing through brushes it's fine.