Classic Army SCAR-H Pinion Gear Stripping

W@tchtower · May 24th, 2011, 15:28

I've just recently went through my second pinion gear on a TM motor with my CA SCAR-H. Now either the gearbox has been shimmed incorrectly or there is an obvious incompatibility between the longer mechbox of the SCAR-H and the TM motor.

Any thoughts?

voorhees -FWA- · May 24th, 2011, 23:57

It's probably bad shimming. More than likely your shimming is too tight making your motor work harder to cycle the gears. This will strip your pinion gear in the end.
Your motor hieght may be too high also...
When you fire the SCAR, does the motor and/or the battery get hot?
Try to shim the gearbox so you have at least 1mm movement up and down on the shaft. This way when you screw the box together the gears will be held firmly; not tight and not loose.
Adjust your motor starting at its lowest position (screwed all the way out) and slowly turn it in and listen to the motor. When it's at the perfect hieght you shouldn't hear any squealing and it sound (normal?).
Try using a higher end pinion gear too, Element and Modify may be a little weak for most applications.

W@tchtower · May 25th, 2011, 02:39

It's not that the motor is in too far because it works until all I hear is the motor spinning freely, not catching the bevel gear. Upon inspection afterwards the pinion is so stripped that it is not useable anymore and needs to be replaced. This has happened to two pinions already! I will check the shimming tomorrow but a friend of mine had told me that he's been using an unshimmed gearbox for over a year and hasn't had to replace it yet, so I'm willing to try the shimming suggestions but I am also looking into things such as changing the gear set or a new motor even.

sushicake · May 25th, 2011, 11:19

What fps is your gun running? Maybe the stock TM motor cant pull that much.

W@tchtower · May 25th, 2011, 12:55

My gun is running at ~400 fps and it's a long type TM High Torque motor, if that helps.

Azathoth · May 25th, 2011, 13:35

The problem lies in shimming and/or motor height.

If your pinion gear is worn out just at the tip or so, that is definietely a motor height issue and possible addition of poor shimming.

W@tchtower · May 26th, 2011, 17:43

After reading a bit into magpul grips I've been told/read that there are issues with the magpul grip not being a good fit for the motor and causing issues.

Anybody have experience/knowledge of this?

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May 24th, 2011, 15:28	#1
W@tchtower Trader rating Join Date: Feb 2011 Location: Peterborough	Classic Army SCAR-H Pinion Gear Stripping I've just recently went through my second pinion gear on a TM motor with my CA SCAR-H. Now either the gearbox has been shimmed incorrectly or there is an obvious incompatibility between the longer mechbox of the SCAR-H and the TM motor. Any thoughts?

May 25th, 2011, 11:19	#4
sushicake Trader rating Join Date: Dec 2008 Location: Markham, ON	What fps is your gun running? Maybe the stock TM motor cant pull that much. __________________ "Don't you know the first law of physics? Anything fun costs atleast $8"

May 24th, 2011, 23:57	#2
voorhees -FWA- Trader rating Join Date: Oct 2008 Location: Estevan, Saskatchewan	It's probably bad shimming. More than likely your shimming is too tight making your motor work harder to cycle the gears. This will strip your pinion gear in the end. Your motor hieght may be too high also... When you fire the SCAR, does the motor and/or the battery get hot? Try to shim the gearbox so you have at least 1mm movement up and down on the shaft. This way when you screw the box together the gears will be held firmly; not tight and not loose. Adjust your motor starting at its lowest position (screwed all the way out) and slowly turn it in and listen to the motor. When it's at the perfect hieght you shouldn't hear any squealing and it sound (normal?). Try using a higher end pinion gear too, Element and Modify may be a little weak for most applications.

May 25th, 2011, 02:39	#3
W@tchtower Trader rating Join Date: Feb 2011 Location: Peterborough	It's not that the motor is in too far because it works until all I hear is the motor spinning freely, not catching the bevel gear. Upon inspection afterwards the pinion is so stripped that it is not useable anymore and needs to be replaced. This has happened to two pinions already! I will check the shimming tomorrow but a friend of mine had told me that he's been using an unshimmed gearbox for over a year and hasn't had to replace it yet, so I'm willing to try the shimming suggestions but I am also looking into things such as changing the gear set or a new motor even.

May 25th, 2011, 12:55	#5
W@tchtower Trader rating Join Date: Feb 2011 Location: Peterborough	My gun is running at ~400 fps and it's a long type TM High Torque motor, if that helps.

May 26th, 2011, 17:43	#7
W@tchtower Trader rating Join Date: Feb 2011 Location: Peterborough	After reading a bit into magpul grips I've been told/read that there are issues with the magpul grip not being a good fit for the motor and causing issues. Anybody have experience/knowledge of this?

Classic Army SCAR-H Pinion Gear Stripping

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