To add to Trent's CYMA V3 Gearbox issues.... I got the Guarder NB-53 Gearbox Shell and toss in my SMP into it... Here are some results from measurement.
BTW, for future reference, the solenoid is a MAC Bullet Valve, P/N: BV214A-CB0-00-BCVA-CTA, Spec: 6.0vdc, with a 6.0W Consumption rate.
Catalog
Gearbox Measurements:
Initially TJC was saying how much further back the SMP sat in the CYMA gearbox, which makes tip of the nozzle have an open gap between the bucking, thus creating air inefficiencies. The images below should tell the story of how much difference is between the CYMA and Guarder. This is an avid topic on the Wolverine SMP page on FB.
The best bet with observing nozzle seal issues, when the gun is all up and running, note the unloaded BB feedport on the hop up if you feel air back pressure between cycles. Between dry fire cycles, observe if the nozzle tip meets the bucking. Cycle some BBs thru gun and remove the mag while the gun is upside down. There should be at least 5 bbs in the hopup chamber. 4 will roll out when you flip the gun. The last BB is in the bucking chamber. When you cycle the gun, does the BB exit out of the barrel or feed port. If the last bb came back out of the feed port, that may have signs of air back pressure. With my guarder gearbox setup with an air tight seal (with Prowin or Fox Custom Hopup, more later) that last bb should go out the barrel.
Shimming:
With the SMP (in the Guarder GB), it was a direct drop in unlike the CYMA and heavily modifying the gearbox to make it fit. Though, there is a slight movement with engine due to the wide tolerances in the engine and gearbox. Teflon tape is your best friend to shim. Below show the gap when the engine is not shimmed.
MODs to the gearbox:
There were minor mods to make with the guarder gb. Though, I assume every gearbox out there regardless if it's the same model or different will have different tolerances. My setup, I had slightly dremmeled a corner of the trigger circuit board assembly to make room for the spring to rest on the gearbox. The trigger mounting holes were slightly dremmeled due to the slim tolerance differences due to the paint (which adds mils of thickness to the surface). The fire trigger was wire brushed to clean the paint, again to minimize tolerance issues.
HOPUP Unit:
Reading forums and discussions, alot recommend the V3 Prowin or Fox Customs hopup Unit. To address alignment issues, it's best to shine some light thru the BB feed port and stare down the unloaded barrel to see the nozzle alignment. With the Prowin style hopup unit, there is a slot in the back of the hopup unit can be mounted to the gearbox. In the CYMA stock hopup unit, its mounted to the outer barrel. Which can give you millimeter of a gap which can cause air inefficiencies.
I mounted the Fox Customs unit. Though, FOX's website can be misleading. The V3 HOPUP Unit resembles the SHS Hopup unit, but it seems they have updated the style to look like the Prowin. Ordered thru AMPEDAIRSOFT. Similar price to the Prowin.
