Upgraded P90, Time to Get Rid of The Twang Noise!

[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Twang is barely there with the SHS M90, fps seems quite consistent at 320 (shame it's at the low end).

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[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Okay, so the twang is STILL there. Like I said, it's better with the SHS, but I'm still getting bugged by it.

A little research dug this video up...

..exactly the same noise, and you can see what's happening. I've done more reading, and it seems that longer, irregularly pitched springs in some clone guns seem to cause this.

For the record, I compared the springs I have, the OEM one being far stronger and quite a bit shorter than the others. I think to fix this I need a stronger spring that I can then cut down to the same length as the OEM, in theory stopping the noise and maintaining the required FPS. A project for another time though, I'll live with it for the time being.

[richardy]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Twang will always be there with after market springs and metal spring guides plus the p90 is next to your ear so it's more pronounced.

Try a plastic middle spring guide like the promy one maybe and or grease.

It's not length as you say uncompressed it's longer than the gb space.

[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Middle spring guide?

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[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

For some reason, my brain went to sleep! You mean the Prommy plastics guide with metal bearings? Right... that's on my ' to buy' list. Do you have first hand experience of this in the past Richardy?

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[richardy]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

just from making the springs, there really isn't much to them to be that much different from spring to spring. Compressed length needs to be short enough to be compressed in the mech box by the gears and piston. At this point the spring is inside the piston and so is the spring guide. So size wise it cant be too small as to not fit over the spring guide diameter and to big as to not fit inside the piston. So when making the spring ultimately the end length can simply be a result of trying to acheive a certain rating give max width, min width and maximum compressed length.

So if all springs are the smae roughly then whats different, TM springs come attached to the piston head. That could prevent a certain amount of after rattle after each shot but like has been mentioned the spring is bigger than the mech box. So does this really affect it. I think its more likely the fact that when its compressed although its on a guide a certain part of the middle section of the spring will remain flexed agasint the edge of the gearbox.. its why somes times when you remove coloured springs they have worn in the middle on the side. This ultimately is metal on metal the same as spring guide is metal on metal.

Those are the only two metal on metal points i can think of and your trying to reduce twang .. so makes sense to remove or reduce those metal on metal impact areas. but then you dont want to cyma cake your gearbox grease. Most of us tidy up the gearboxes when we go in and fit an after market spring and usually a spring guide, it just makes sense that the twang is simply a result of our cleanliness, spring guide and springs than, certain springs being the issue.

especially since you've already added evidence of testing multiple springs with no change in results.

and when i had a p90 it was right next to my ear and i could hear every fart it made.

[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

There was a definite difference once the SHS was fitted. It's still there, but nowhere near as pronounced. I think the looser coils on the nonlinear springs are the culprit. They allow more rebound the linear OEM spring. It seems to be the common denominator in all the threads I've read about this problem. Maybe the twang is the rebound on the metal guide? I'll order a plastic one, see if there's a difference.

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[Pepperisit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Could you fit a rubber O ring over the end of the spring guide? (Probably a bit late or way too simple... but still!)

[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

I think it's twanging against the whole shaft. If it IS, then Richardy's suggestion of a plastic guide is cock on.

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[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!



One side of the spring guide, unmarked.



Other side, showing visible chaffing. Guide was perfectly seated, no sign of actual scratch marks, leading me to believe that after release, the spring is rebounding against the shaft, giving the distinctive twang. No real evidence of it hitting the gearbox body either.



Possible solution? The chaffing is very slight, so I think the wear that the heat shrink would suffer would be negligible. I'm not using this though, I would prefer to attempt it with adhesive lined heat shrink if I was going to try it at all, minimise the chance of rogue pieces ending up in the gearbox.

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[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Gaurder SP100 spring fitted with a new ASG air nozzle and new TM hop up and #14 o-ring. Much more accuracy, better shot and FPS consistency and back up to 345fps +/-5.

Twang has changed again, a lot sharper, but quieter, less cartoon-like. I can live with that.

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[dadio]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

possibly a sorbothane washer under a metal one inside the piston could help ? but would add weight in the piston as a down side but it would be difficult to fit on the spring guide.sounds odd but have you try'd changing the piston , some have a smaller internal bore that might dampen the spring vibration ?

[RitchieTheBrit]

Re: Upgraded P90, Time to Get Rid of The Twang Noise!

Change of piston could work. I'll have to Google around, see of there's a comparison of internal diameters!

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