M4 making strange grinding noise.

[Mirodasc]

So, at the end of my day last time I played, my M4 was making a loud grinding noise when ever I shot, so I stopped.
Took her apart today and this is what I found:


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SO, clearly this is a problem, my question is, what caused it, and what would I have to do to stop this from happening again.
Also, will the gears need to be replaced as well?

Thanks guys.

[surebet]

Motor pinion gear needs to be replaced (or replace the motor completely if the gear can't be pulled, I forget).

Check the related gears for damage.

Probable cause is a misadjusted motor height, search the forums for a detailed guide to adjust it.

[MaciekA]

Originally Posted by Mirodasc

SO, clearly this is a problem, my question is, what caused it, and what would I have to do to stop this from happening again.
Also, will the gears need to be replaced as well?

Thanks guys.

Is your M4 a G&P? If so, was there loctite or threadlock applied to the motor height adjustment screw or did you use it stock?

I've seen a couple of G&P pinions stripped this way due to the motor gradually dropping during play because the adjustment screw gradually twisted itself out.

[L473ncy]

I suspect it's cause the motor height was too low and the gears on the pinion just sheared off/got worn down.

Open it up and check the gears see if there's any damage to the bevel, spur or sector gear or if they're wearing down. If you can't do it yourself, take it to Optix and he should be able to sort it out for you. If it's a stock G&P yeah... their gears are known for shredding or the axles just shearing off...

You'd think with such great externals they could design/manufacture a gear that wouldn't fall apart like it was a cheap ACM china clone POS but yeah...

[Danke]

I'm starting to think it's not to bad to see a pinion wearing out.

Sure it's an inconvenience but if it's soft enough to just wear on it's own and take no other parts with it when not adjusted correctly then it's not the end of the world.

[Ace of Spades©]

Its not the motor height, its the actual pinion gear on the G&P M120 motor. I've seen first hand three of the M120 pinion gears exactly like the one pictures (Including my own). They are soft as butter and shear like crazy. Just pull it and replace it with a Modify one and you should be good.

[Azathoth]

I personally have never had a problem with the G&P Pinion gear, but I've seen every brand of pinion gear get ripped up like the one above. It's almost always is a symptom ofeither

1) Terrible motor height adjustment.
2) Over / Under shimming on the bevel gear.

[damage]

Originally Posted by Azathoth

1) Terrible motor height adjustment.
2) Over / Under shimming on the bevel gear.

+1

I have the same motor and I had it for 3 yrs. Just normal wear.

[AngelusNex]

Originally Posted by Azathoth

I personally have never had a problem with the G&P Pinion gear, but I've seen every brand of pinion gear get ripped up like the one above. It's almost always is a symptom ofeither

1) Terrible motor height adjustment.
2) Over / Under shimming on the bevel gear.

Originally Posted by damage

+1

I have the same motor and I had it for 3 yrs. Just normal wear.

It's only the M120 that has a shit pinion gear. Their other midles are great but for somereason they guve the m120 shit. The ONLY pinion gears i've seen strip are G&P M120s, some I set height myself while th JG one in my 416, also set by me has lasted 3+ years.

[ThunderCactus]

Never had an issue with any G&P pinion gears, even M120s, and I've worked on a lot of G&Ps
Like Azathoth said, check your motor height. If the proper motor height can't be achieved, re-shim your bevel gear closer to the motor.
While you're in there, you should re-shim all the gears properly if it hasn't been done already