Airsoft Canada - View Single Post - TM MP5A4/A5 Gear Replacement Help Needed!

GODSPEED|seven · November 14th, 2010, 02:20

Hi, I have this old TM MP5A4/A5 that was working like a charm, until earlier today; as I was firing it, all of a sudden the sound went from clear crisp pops (shooting) to high pitch whine (not shooting).

When I got home, I tried adjusting the motor height by +/- 1mm with no effect. So I decided to take the gun apart and open up the gearbox..

It's pretty much all stock TM parts. I noticed that the top-most gear (the one that engages the piston) has 3-4 teeth (on the lower part of that gear, not the part that actually engages the piston) that are completely eaten away. I guess it was old (I have the TM EG560 Motor.. or is it 650.. I forget). But I also noticed the piston had the 2nd, 3rd & 4th teeth quite alot shorter than the rest (like half eaten away). The 1st big 'tooth' is fine.

While It was my first time having to open a gearbox, I'm not scared to have to play inside of it. I closed it all back up and everything fit nice and well...

BUT, my issue is this:

What type of gears do I need?

Should I replace the Piston?

I was looking at the following parts:

Modify V2/V3/V6 Top Speed Gearset
http://www.airsoftparts.ca/store2/in...oducts_id=1568

to go with this:

Modify High Speed Ultra Piston - New Version
http://www.airsoftparts.ca/store2/in...oducts_id=1369

or

StormTech MAX Impact Polycarbonate Piston
http://www.airsoftparts.ca/store2/in...oducts_id=1495

The gun is all stock TM, while I'm not currently looking to upgrade anything, I want to keep the option open for putting in a M100 Spring.

I want to keep the 750-850 Rounds/min ROF (using a Ni-MH 8.4v 2500mAh Large type). The sound on it with the stock parts was just beautiful; no whining at all, just nice clear and crisp "pops".

I understand there are various different metals for gears, as well as high speed, ultra high speed and the torque ones.. Since my gun is shooting a M90 Spring I believe, I must stick with the speed ones (which I like).

The gearbox does not appear to have bearings, but just nylon inserts (which is also better for lower powered quick firing guns.. from what I understand).

I would like to buy parts from Canadian Retailers.. to avoid a 2-3 week shipping time. And would really like to keep the cost below 100$.

All help/tips/links is greatly appreciated!

November 14th, 2010, 02:20	#1
GODSPEED\|seven Trader rating Join Date: Mar 2010	TM MP5A4/A5 Gear Replacement Help Needed! Hi, I have this old TM MP5A4/A5 that was working like a charm, until earlier today; as I was firing it, all of a sudden the sound went from clear crisp pops (shooting) to high pitch whine (not shooting). When I got home, I tried adjusting the motor height by +/- 1mm with no effect. So I decided to take the gun apart and open up the gearbox.. It's pretty much all stock TM parts. I noticed that the top-most gear (the one that engages the piston) has 3-4 teeth (on the lower part of that gear, not the part that actually engages the piston) that are completely eaten away. I guess it was old (I have the TM EG560 Motor.. or is it 650.. I forget). But I also noticed the piston had the 2nd, 3rd & 4th teeth quite alot shorter than the rest (like half eaten away). The 1st big 'tooth' is fine. While It was my first time having to open a gearbox, I'm not scared to have to play inside of it. I closed it all back up and everything fit nice and well... BUT, my issue is this: What type of gears do I need? Should I replace the Piston? I was looking at the following parts: Modify V2/V3/V6 Top Speed Gearset http://www.airsoftparts.ca/store2/in...oducts_id=1568 to go with this: Modify High Speed Ultra Piston - New Version http://www.airsoftparts.ca/store2/in...oducts_id=1369 or StormTech MAX Impact Polycarbonate Piston http://www.airsoftparts.ca/store2/in...oducts_id=1495 The gun is all stock TM, while I'm not currently looking to upgrade anything, I want to keep the option open for putting in a M100 Spring. I want to keep the 750-850 Rounds/min ROF (using a Ni-MH 8.4v 2500mAh Large type). The sound on it with the stock parts was just beautiful; no whining at all, just nice clear and crisp "pops". I understand there are various different metals for gears, as well as high speed, ultra high speed and the torque ones.. Since my gun is shooting a M90 Spring I believe, I must stick with the speed ones (which I like). The gearbox does not appear to have bearings, but just nylon inserts (which is also better for lower powered quick firing guns.. from what I understand). I would like to buy parts from Canadian Retailers.. to avoid a 2-3 week shipping time. And would really like to keep the cost below 100$. All help/tips/links is greatly appreciated!