Striped Gears

[cratedriver]

Well i was out last night with my stock TM MP5 SD5 and whammo... one of the gears stripped and broke the teeth right off. I also noticed one of those notorious plastic bushings had broken in two. What sucks even more is i've only been using the gun for the past 2 weeks and i've only owned it for 1.5 months. Oh well... 'tis the world of airsoft I guess. :kill:

The problem started when I think I got a stuck BB in the hop up. I tried clearing it by firing it a few times... that's when it happened. Now I know better. :nod:

Anyhow. I've ordered some new parts to repair the situation and i'd like some opinions on whether you think it will help this from happening again.

Here's what i've ordered for the mechbox for now.

1 x Systema Precision Shim Set
1 x Airsoft Elite Oiless Steel Bushings
1 x Systema flat gear set

So what do you think? I am planning on a spring and cylinder upgrade in a while, but first I want the damn thing to work again.

What should I watch out for when putting this back together?

Appreciate the help!

[Mantelope]

You should get someone who's done upgrades before to do it. Precise shimming is not an easy skill, and if you're looking for reliability, you're going to want experienced to do it.

What battery are you using? That kind of damage is almost unheard of in a new, stock TM. The only cause I can think of is if you're using an extremely powerful battery and the gears are cycling faster than the piston can return to battery.

[Greylocks]

http://www.airsoftcanada.com/showthread.php?t=14503

You have a problem that belongs in the Doctor's list, not in the Solutions list.

Is that gun new or second-hand? Was it ever taken apart before? Was the motor seated properly?
I have yet to hear of a stock gun breaking so fast, most work for years.

For a bushing to break, you need excessive stress on the gears. Usually it's because someone put a stronger spring in there and nothing else... the other reason would be that it was opened and not properly re-assembled.

So apart from that, the previous advice is your best bet; find a local expert.

[cratedriver]

I use an 8.4V 3300 mAH Battery

It's a brand new gun from 007 airsoft. I have never taken it apart before this happened. It had only been used for two weeks prior to last night. I was waiting for my battery from outside Canada. By the time it arrived it was a month before I could actually use the gun. Unfortunately the warranty was only good for 14 days. So my only option is to repair it. It just decided to fall apart on me. I understand getting a pro to look at it is a great idea, but do you think the parts I bought will do the trick? I want strength so this won't happen again.. or at least for a long time.

[mcguyver]

make sure your bushings from airsoft elite say on the package "for tokyo marui". they sell other ones for ics and a.e. aegs that ARE NOT COMPATIBLE with tm guns. they are meant for a smaller gear shaft size and will not work at all. i have both on my bench now and found that out.

[ILLusion]

It could also have been caused by your hop-up being set too high.

In my opinion, that battery you're using is excessive for a stock Marui gun and will definitely shear the teeth off some gears if a jam occurs.

[Greylocks]

If you want a cheaper solution; normal powered battery, normal bushings, 'stock' gears, expertise to assemble.

Alternate 1; reinforced gears, new piston if it got chewed up, mild spring, bushings, expertise to assemble.

Originally Posted by ILLusion

In my opinion, that battery you're using is excessive for a stock Marui gun

if im not mistaken, on TM manuals they use a 7.2v battery and you can upgrade to the HYPER COMMAND 8.4v

but the excessivness would be to the idea that more mah can increase performance

[Blackthorne]

I have been warned by my Gun Doctor to avoid the oilless bushings.

He says they are unreliable from the perspective of delivering proper lubrication to the system. Especially at the two extremes of performance, when the gun is cold and just starting to fire and when you are full auto and really working it.

He (and I) prefer the grease and regular maintainace.

Besides, regular maintainance gets you familiar with your gun and it's inner workings.

As far as upgrades, it's like throwing nitrous on your car. Sure, your gonna get power, but if you don't upgrade everything else in the power chain, your gonna snap a crank or throw a piston.

If you throw in a bigger battery, you are intorducting extra stress to the motor and everything it connects to (e.g. gears, pistons and mechboxes). Unless it's a front to back upgrade you are going to see that stress come out in different ways, like stripped gears on a jam, and cracked mechboxes after smacking your piston harder on the powerstroke.

Not to say you can't do it a bit at a time, but once it's apart, might as well do as much as you can!

[ILLusion]

Originally Posted by Blackthorne

I have been warned by my Gun Doctor to avoid the oilless bushings.

He says they are unreliable from the perspective of delivering proper lubrication to the system. Especially at the two extremes of performance, when the gun is cold and just starting to fire and when you are full auto and really working it.

Does your gun docter realize that almost all metal bushings are of the "oilless" variety and made from sintered alloys? The only ones that I can think of that aren't made this way are Guarder and Gun Design bushings - both of which I've seen oxidize due to their high iron content and lack of impregnated oil.

There's a reason why bushings are made from a sintering process in many industries and impregnated with oil - it's the best way to handle a high stress load with an expected high life cycle.

Regardless, you never install any bushings or bearings dry. Add some lube. Just because they're called "oilless" doesn't mean you don't use any lube with them. You're suppose to add grease to them, making their performance at least the same as non-sintered bushings, if not better.

[cratedriver]

All sound like great suggestions. Thanks for the info.