gearbox problems

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Fat-jd

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having a nightmare of a time with my v2 gearbox hope someone can help out 

2 weeks ago had a loud cracking sound come from my m16 and stopped working done a load of research then opened the gearbox found out that the piston head had came off causing damage rebuilt the gearbox with a new g&p piston body, systema piston chamber, new spring, cleaned and regressed gearbox fired about 500 bbs then crack and stops working again, opened up the gb again and the spur gear shaft as snapped anyone got any idea why this would happen and what would be the best set to fit 

Cheers 

 
What battery are you using? Just wondering if you’re over powering the gearbox or you just got lucky?

 
only a 7.4 lipo do you think it could be down to shim issues ?

 
What make gearbox? Was the shimming and angle of engagement checked and adjusted?

 
it's a g&p unit with a a systema piston chamber elements piston head and a sp100 spring .

the g&p piston body has the aoe mod already done as standard and I didn't change the shiming but it's always been a bit whiney  

 
The original smash probably cracked the spur gear. The spur gear then failed to fatigue stresses.
 
You may have damage to the other gears as well.

Best solution is a new gear set, That way you get a matching mesh across all the gears, and know there is not any invisible damage on those parts to cause a future smash.

You also need to thoroughly inspect the pinion gear on the motor. Check for cracks forming in the teeth, and in line with the motor shaft.

If your gearbox has bearings it would be a good idea to inspect those as well, Especially the spur gear bearings as they take the most abuse through a twisting motion present in all gearboxes.

 
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do you think of be better going for a different ratio gear set or keep it standard what gear set would you recommend 

was thinking of getting a new motor but not to sure what to go for 

 
If you want a new motor for 7.4 lipo then I highly recommend the asg ultimate line up. There about £50

The asg ultimate cnc 30000 would see 20 rps. Most boxes can cope with that without many problems. Failing that the SHS High speed is also a decent enough pick for stock gears (18:1) pulling an M100 it'll be slightly faster than the ASG but it also produces a lot more heat.

For your gears I'm not much help, All my guns are either stock or running JG 18:1 sets. The JG gears are probably the best value for money sets, and they seem to be reasonably well hardened. You just have to spend a little time with them before you install making sure they mesh nice, and taking off the burrs with a warding file. Should cost about £15 for a set. Going with a brand name is sometimes a gamble on gears, some of the well respected names sell very soft sets that are only O.K in a non upgraded gun. The JG ones on the other hand seem to be made to be abused.

https://www.davescustomairsoft.co.uk/Internal-Parts/gear-gears?product_id=1270

 
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Gear wise, I’d recommend Rocket gears from @ak2m4, made in the same factory as SHS(which are great) but cheaper.

 
Budget trigger response Rocket Airsoft /SHS high torque motor, 13:1 gears, ZCI enhanced bushes instead of the bearings. The stock G&P wiring and air seal components are fine. Add a basic Mosfet. That'll get you a solid 20rps with good trigger response on 7.4v.

AOE adjustment isn't just removing the teeth on the piston itself, but also adding material to the inside of the cylinder head to position the piston slightly further back.

Ak2m4.co.uk for your parts.

 
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this is how is set the aoe see pic checked gears for movement and shimed accordingly as for motor height i checked that the bottom of the motor gear was on the outer edge of the pinion gear 

View attachment 32267

 
Fat-jd said:
this is how is set the aoe see pic checked gears for movement and shimed accordingly as for motor height i checked that the bottom of the motor gear was on the outer edge of the pinion gear 

View attachment 32267
Click to expand...
Click to shrink...


Yeah...that's not great, to properly correct AoE the mating surface of the sector gear tooth should meet the pickup gear with no angle between them. 



 
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Fat-jd said:
this is how is set the aoe see pic checked gears for movement and shimed accordingly as for motor height i checked that the bottom of the motor gear was on the outer edge of the pinion gear 

View attachment 32267
Click to expand...
Click to shrink...


That 's actually going to cause more problems than it solves. The pickup tooth on the piston should be over the sector gear axle (ish). Get yourself a couple of shower hose washers and glue them to the inside of the cylinder head to position the piston slightly further back.

 
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