[Flarebrass]

Hello ACS Community!,

So I am back for a second round of a high end build I am doing. I used everything I learned from my previous builds to this date, including my other troubleshooting thread, and everything worked as it has in the past or better; other than one thing.

I put everything together after modification and began testing. It shoots just below 400 FPS as intended consistently and seems almost every part if working correctly. Now, to the issue;

whether it be on semi or auto, there is a subtle "grinding" metal-on-metal noise when the trigger is pulled. I know this as some of my other build have a much "smoother" sound when pulling the trigger. This would seem to be from the pinion gear and the bevel gear.

I found this out the hard way after I pushed through a scrim testing it out, got home and found both the bevel and pinion gear beginning to strip and the gearbox was full of sheered metal (had already lost a mm or two of metal from each set of teeth). Since then, I have replaced the bevel with another one that is exactly the same but not stripped, and also switched the pinion. Neither are stripped now, but the grinding still exists.

Now, some of my in-house trouble shooting is as follows:

1) Recheck shimming: Checked and re-shimmed 3 times. Shimming every time was right on. I also triple checked the motor height on the right side of the gearbox with the grip and motor installed to confirm height. Everything was ok with that as well.

The thing that I did notice though was that when the motor test was done to check height, it pushed the bevel gear onto an angle (possible saying that the motor height was fine, but the width from side to side was off and creating additional pressure on the pinion and bevel teeth when installed which is a good probability to being the culprit). I tested the bevel with no shims on the fat side, and it still produced this result.

*The above is my best guess as to the issue, but I have not yet found a solution to relieve pressure from the teeth when the gearbox is assembles and the motor is installed as the bevel cannot go any lower*

2) tested what side the wires should go on. Tested all 3 in the grip; both wires front, one wire each side and both wires on the back. This produced the same result of grinding for each test.

3) I compared the pinion on the A1 to a spare SHS pinion I bought just incase I needed to replace one, they are both the same size and seemingly same angle.

4) I did NOT test another motor, as the A1 is the only one I own that can pull those gears.

5) checked the bearing to ensure that they are flush with the body of the gearbox. Test concluded to be ok.

Bellow is my complete gearbox setup for my other VFC 416 CQB:

Lonex Gearbox (bearings, not bushings)
SHS M4 nozzle
Lonex aluminum double o-ring cylinder head (equipped with 70D sorbo pad)
Stock VFC Cylinder with a type-1/2 slit (works the best with the short stroking set up for this particular build)
Siegetek Revolution 10.44:1 Gearset SSG (short stroked 3 teeth off pick up side)
Lonex Titan A1 Motor
SHS 15 tooth piston - full metal rack (filed 2 teeth after pickup tooth for AOE correction, short stroked 3 teeth off release side and fully swiss cheesed)
Lonex POM Ventilated Piston head (Ball bearings installed)
Lonex bearings spring guide
SHS tappet plate (modified to fit into Lonex reinforced gearbox)
Lonex selector plates
Lonex M120 non-linear spring
BTC Spectre MOSFET
Magpul PTS MOE grip

If you could please let me know your opinion on this matter and if you know what may help, it would be greatly appreciated. Thanks for your time.

Flarebrass