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Dead motor in sr-12.. Any tips on a replacement?


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#1 Gojyumatt

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Posted 06 April 2014 - 10:21 PM

The title basically sums it up.  Motor died while playing yesterday and I was just wondering if anyone had any suggestions on an aftermarket motor or if I should replace it with another kwa stock motor.  

I would also like to ask opinions on why the motor could have failed in the first place.   The gun doesn't get used much so I was real surprised when it failed.   I'm positive it is the motor as I've already taken the motor out of my km-4 and tested it out and the gun worked great.  
I've swapped out my springs for m130s and im a little concerned it is putting to much strain on the motor and that's what caused the failure.    I run the same spring in my km4 (which gets more use) and is still running great, but worried it will lead to failure in that gun in the near future.

I plan on putting the factory springs back in both guns as they shoot to hot for all my local fields, but do you guys think that could of caused the motor failure or are the kwa stock motors capable of pulling the m130 without a problem?       Since the spring change the sr-12 has maybe 5,000 rounds fired at the very Max.  The m4 has double that.    

Any opinions on new motors or the failure reason on my current one will be greatly appreciated!!

Thanks so much guys!



#2 Larry

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Posted 07 April 2014 - 06:24 AM

I have a JBU red motor (torque) in a SR10. Stays cool and good trigger response with a 7.4 2200 mah. 19/20 rps.

#3 tales

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Posted 07 April 2014 - 07:13 AM

The failure of your current motor, if it doesn't smell burned. There is a good chance its in the brushes. Have you ever removed the brushes on a motor before?

The shunt wire (the wire that comes out of the brush) is wrapped around the spring clasp. Its common for the shunt wire or the spring to get hung up on the brush hood. There are slots on both sides of the brush hood: one is for the spring, the other is for the shunt wire. So they can move in as the brush wears.

Motore on left. You can see the wire & spring are in the brush hood slots.
Posted Image

Same here
Posted Image

There is a chance the brush cracked, when you remove a brush, its best to install it the same way it was removed.
Do one at a time and don't reverse them, turn them upside down. They wear different, so install them the way they came out.

Then it could be the KWA motor died :(
I have found some quality motors at good prices. $30+ shipping. They use a D pinion gear. That will save you money buying a gear puller & the quality is like SHS "D" pinions or close to it.

This: ZCI high torque.  Link
http://www.clandesti...d8cedc73b375b50
Posted Image

Edited by tales, 07 April 2014 - 07:19 AM.


#4 vanevery

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Posted 07 April 2014 - 08:16 AM

Big fan of ZCI Motors.

Not a fan of their Pinion Gears.
One of my ZCI Pinion Gears just fell right off when removing the motor.
They also do not mesh perfect with KWA Bevel gears, but are not horrible in this respect either.
An SHS Pinion Gear is always a great choice for Pinion Gear replacement.

Be careful in Full-Auto with the ZCI Motors.
If your gun is not fully tuned to accommodate high speed you will most likely get pre-engagement issues.
This just happened to a previous customer of mine with his all stock, never opened up, KWA m4 after maybe a 1000 rounds on the ZCI HT motor and using a 11.1v/1500mah/15C Li-po.
I will be fixing his gun for him and doing a full-tune up on the gearbox this week.

#5 BLATEY

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Posted 07 April 2014 - 09:26 AM

What motors would you recommend around $30? I'm going to build a SR-47(if it's not too expensive). I play field and some cqb would like it to pull an m120-30 smoothly and rof around 15-20 with nice trigger pull.

#6 tales

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Posted 07 April 2014 - 10:10 AM

View Postvanevery, on 07 April 2014 - 08:16 AM, said:

Big fan of ZCI Motors.

Not a fan of their Pinion Gears.
One of my ZCI Pinion Gears just fell right off when removing the motor.
They also do not mesh perfect with KWA Bevel gears, but are not horrible in this respect either.
An SHS Pinion Gear is always a great choice for Pinion Gear replacement.

Be careful in Full-Auto with the ZCI Motors.
If your gun is not fully tuned to accommodate high speed you will most likely get pre-engagement issues.
This just happened to a previous customer of mine with his all stock, never opened up, KWA m4 after maybe a 1000 rounds on the ZCI HT motor and using a 11.1v/1500mah/15C Li-po.
I will be fixing his gun for him and doing a full-tune up on the gearbox this week.

Van, would you mind posting your experience in the motor thread & maybe the HC also?

#7 tales

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Posted 07 April 2014 - 10:12 AM

View PostLarry, on 07 April 2014 - 06:24 AM, said:

I have a JBU red motor (torque) in a SR10. Stays cool and good trigger response with a 7.4 2200 mah. 19/20 rps.

Larry, would you mind posting your thought's on the JBU red?

#8 tales

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Posted 07 April 2014 - 10:43 AM

View PostBLATEY, on 07 April 2014 - 09:26 AM, said:

What motors would you recommend around $30? I'm going to build a SR-47(if it's not too expensive). I play field and some cqb would like it to pull an m120-30 smoothly and rof around 15-20 with nice trigger pull.

The motor above. Maybe a different pinion you can't see the gears so you don't know how they mesh. By ear?  that may not work unless there is a major problem.

Since no gear company tells us the pitch of there gears, i rolled out around 6- different gears from "top companies" & they are all the same pitch (it was a low number & mostlikely a difference in production that will not be noticed ) As for pre engagement the motor is equal or close to A2s & 35000s none show any pre engagement, JMO.  Ask what van likes in a D pinion. BUT if you do go with that motor, the pinion is good. Use it then switch to another company. Its a good motor for what price range you asked.

Other's should be able to help, as all guns are different. This does work for me.

Good Luck!

Edited by tales, 07 April 2014 - 12:10 PM.


#9 gcw360

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Posted 07 April 2014 - 01:40 PM

View PostGojyumatt, on 06 April 2014 - 10:21 PM, said:

The title basically sums it up.  Motor died while playing yesterday and I was just wondering if anyone had any suggestions on an aftermarket motor or if I should replace it with another kwa stock motor.  

I would also like to ask opinions on why the motor could have failed in the first place.   The gun doesn't get used much so I was real surprised when it failed.   I'm positive it is the motor as I've already taken the motor out of my km-4 and tested it out and the gun worked great.  
I've swapped out my springs for m130s and im a little concerned it is putting to much strain on the motor and that's what caused the failure. I run the same spring in my km4 (which gets more use) and is still running great, but worried it will lead to failure in that gun in the near future.

I plan on putting the factory springs back in both guns as they shoot to hot for all my local fields, but do you guys think that could of caused the motor failure or are the kwa stock motors capable of pulling the m130 without a problem?    Since the spring change the sr-12 has maybe 5,000 rounds fired at the very Max.  The m4 has double that.

Any opinions on new motors or the failure reason on my current one will be greatly appreciated!!

Thanks so much guys!
I haven't read the whole thread yet but a KWA can pull an M130 spring for many thousands of rounds without anything other than general maintenance.

#10 Gojyumatt

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Posted 07 April 2014 - 01:52 PM

Tales... You sir are awesome!!!!!!    I wasn't really sure exactly what you were referring to about the brushes and springs so I watched a quick video on how to change them.   Sure enough.. It worked great after flipping them over like you suggested!!!    

I know it's very hard to judge but with that fix should I still have some decent life left in that motor or should I still be in the market for a replacement?
Also  I wasn't really aware the the pinion gears on other motors might not align right with the kwa gears..   That being said am I  better off with another kwa factory motor?

#11 tales

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Posted 07 April 2014 - 03:15 PM

View PostGojyumatt, on 07 April 2014 - 01:52 PM, said:

Tales... You sir are awesome!!!!!! I wasn't really sure exactly what you were referring to about the brushes and springs so I watched a quick video on how to change them.   Sure enough.. It worked great after flipping them over like you suggested!!!

I know it's very hard to judge but with that fix should I still have some decent life left in that motor or should I still be in the market for a replacement?
Also  I wasn't really aware the the pinion gears on other motors might not align right with the kwa gears..   That being said am I  better off with another kwa factory motor?

I have a hard time explaining things :blush: I found most gears are the same pitch, so they should mesh.

You need to see the pinion meshing with the bevel gear to know if its meshing correctly. Not what it sounds like.

Anyway Im glad you got it working. As the KWA motor will pull a 130 spring.

"decent life left in the motor"
If the wire was hung up it might be time to change the brushes & clean the motor.
I went through some problems finding replacement brushes that have the correct concave, ended up recutting aftermarket brushes.

I still think you will enjoy the motor posted above, when you're ready to change out the KWA motor.

#12 Gojyumatt

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Posted 07 April 2014 - 04:11 PM

Thanks again!!!!  I'm honestly still not 100% sure on why it's even working now.. But doing your tip definitely got it that way!    When I flipped the brush heads I noticed they had more ware on one side of the concave than the other.   So maybe it didn't have full contact??  I have no idea!   But I never in a million years would have thought to flip the brush heads!  I didn't even know it was possible!  So thank you so much again!!!     I am most likely going to purchase a new motor anyway just so I have it when this motor dies fully!    I like the price of the zci you linked and it seems to get great reviews so I will definitely go with that suggestion!      
I am a little confused about the pinion gear talk that was going on though. :/
Is that zci motor you linked basically ready to drop in then adjust the motor height or do I need to buy another pinion gear to replace the one that it comes with?    And if by some chance I do need to swap out the pinion gear can I just use the one from the current kwa motor I have now?  



#13 tales

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Posted 07 April 2014 - 05:05 PM

I think I said don't flip them because they don't wear even

I think the wire  or the spring got stuck on the brush hood where the brush goes, there are slots so as the brush wears the spring & wire can follow the brush into the commutator
(Copper thing the brush touches)
If the brush looses contact with the commutator
The motor won't run

When you reverse the brushes that leaves the pointed part of the brush to contact the comm first
That could break the brush

You can't switch the pinions kwa uses a round hole the zci uses a D shaped hole pinion gear with a set screw you won't need a gear puller like on KWA motors

Sounds like you got a lot of use out of the kwa motor if the brushes are that worn

It's time to replace something brushes or motor
In the future maintain the motor. a few easy steps so when the motors broken in you will get full performance

Also make sure the shunt wire & spring can't  get stuck on the brush hood
And reinstall them the way you removed them

I think the wire was hung up and you freed it when you reversed the brushes

Good luck!

Edited by tales, 07 April 2014 - 05:08 PM.


#14 Gojyumatt

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Posted 07 April 2014 - 05:52 PM

OH!!! I read that wrong!! I thought you meant don't pull them out and switch sides.. And instead take them out and flip it 180 degrees and put back in the same spot. (Which is what I did!).   Again not sure why it works now.    
And before I did that the motor would still fire.. Just not every trigger pull and when it would it didn't have enough strength to pull the spring back.   I should of mentioned that at the beginning of the post but I honestly figured the motor was dead and that's why it sounded so different compared to the motor from my km-4. (Both motors where pulled and tested from the same battery and the sound difference was night and day)

Are brush heads something I can buy to replace or am I better of just doing the whole motor.  It's not like $30 for that zci is expensive so replacing the whole thing isn't really a big deal.   But if it's not necessary I might as well just buy new brush heads if it's an option.

Your also right about putting a lot of rounds through it Tales!  Upon further inspection of my two motors I realize I swapped the motors from the two guns last year when I did the spring change!!   Which would explain why there is so much wear. That motor has had a lot of use in my km-4!    

You mentioned maintenance in future motors so I get peak performance..  Do you have any tips for basic maintenance as I honestly didn't know I had to do anything to it! :/
(And yes I feel real dumb now!!)

Edited by Gojyumatt, 07 April 2014 - 05:54 PM.


#15 tales

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Posted 08 April 2014 - 06:26 AM

I use this on my motor & gearbox bearings

Random links, try local hobby store
http://www3.towerhob...0001p?&I=LXDDHC

After the spray, this oil
http://www.amain.com...Bearing-Oil-2oz

Two likes that should give you a starting point.

Great video
http://www.kwausa.co...?showtopic=8164

This has pics of what a commutator should look like after cleaning. If the KWA motor is still good, and you want to replace the brushes. It also covers some aftermarket brushes
All motors eventually reach there lifespan. if maintained they would last longer.
http://www.kwausa.co...showtopic=11274

#16 vanevery

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Posted 08 April 2014 - 06:47 PM

View Posttales, on 07 April 2014 - 10:10 AM, said:

Van, would you mind posting your experience in the motor thread & maybe the HC also?
The ZCI and HC motors are a beast.
They are by far the best motors for the price out there.
I don't have a lot of rounds on mine or the one I installed into a customers gun.
So, time will be the ultimate judge.

What I have seen I am unbelievably impressed by.
The speed and torque are outstanding.
Neither motor gets hot like the SHS motor.
It just gets as warm like most motors do in heavy use.

Both motors pull heavy springs with ease.
The ZCI motor I just installed in a customers DMR pulls a MadBull m150 spring with ease.
This a linear spring and is actually SP rated though labelled M rated
I will be using this motor in my m170 KWA DMR build.

As far as Pinion gears, SHS are by far the best for the money.
They are built like a tank and mesh well with KWA gears and TM compatible gears.
They are my go to Pinion Gear.

#17 tales

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Posted 08 April 2014 - 07:38 PM

View Postvanevery, on 08 April 2014 - 06:47 PM, said:

The ZCI and HC motors are a beast.
They are by far the best motors for the price out there.
I don't have a lot of rounds on mine or the one I installed into a customers gun.
So, time will be the ultimate judge.

What I have seen I am unbelievably impressed by.
The speed and torque are outstanding.
Neither motor gets hot like the SHS motor.
It just gets as warm like most motors do in heavy use.

Both motors pull heavy springs with ease.
The ZCI motor I just installed in a customers DMR pulls a MadBull m150 spring with ease.
This a linear spring and is actually SP rated though labelled M rated
I will be using this motor in my m170 KWA DMR build.

As far as Pinion gears, SHS are by far the best for the money.
They are built like a tank and mesh well with KWA gears and TM compatible gears.
They are my go to Pinion Gear.

I have to post it in the motor thread. I agree about SHS pinions. Good product good price. Thanks!

#18 Larry

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Posted 09 April 2014 - 07:17 AM

Sold, wanted to put a new motor in one of my guns. ZCI torque sounds good, have used a set of  their 16:1 gears with good success.  I like my JBU but was $40, Clandestine has great shipping rates and have most items to you in 3/4 days.

#19 vanevery

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Posted 12 April 2014 - 11:11 AM

View Postvanevery, on 07 April 2014 - 08:16 AM, said:

Big fan of ZCI Motors.

Not a fan of their Pinion Gears.
One of my ZCI Pinion Gears just fell right off when removing the motor.
They also do not mesh perfect with KWA Bevel gears, but are not horrible in this respect either.
An SHS Pinion Gear is always a great choice for Pinion Gear replacement.

Be careful in Full-Auto with the ZCI Motors.
If your gun is not fully tuned to accommodate high speed you will most likely get pre-engagement issues.
This just happened to a previous customer of mine with his all stock, never opened up, KWA m4 after maybe a 1000 rounds on the ZCI HT motor and using a 11.1v/1500mah/15C Li-po.
I will be fixing his gun for him and doing a full-tune up on the gearbox this week.
Just opened up the gun.
Turns out it was a blown bearing.
The Bevel Gear and Piston look great.
Based on the way the gun sounded, I  was sure it was a PE issue, but it was not.
This gun is an all stock KWA m4. It was purchased in 2011, but has 3gx gears.
The gearbox looks as if it has been opened up before, but was kept to KWA stock parts.
The ROF with the Li-po and ZCI Motor must have been pretty high.
I highly advise anyone who buys a ZCI or HC Motor to fully tune the gearbox if using even a low amp Li-po for their KWA guns.
These Motors are awesome, but need the gearbox tuned up to run a Li-po with them.

I will be doing a full tune-up on this customers gun.
This will include a switch to solid metal Bushings.
This because the ROF will be around the 30rps mark, so it is necessary.

#20 vanevery

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Posted 03 May 2014 - 04:07 PM

Update:

Turns out there was more damage than the blown Ball Bearing Bushing.
This happened at some point in the process of the gun going down.
3gx Spur Gear:
http://i1266.photobu...zps4d864ebb.jpg
I know it is hard to tell form the picture, but the top row set of teeth that engage the Sector Gear are literally sliced in the middle a little bit, thus causing the top half of these gear teeth to fan upwards. I have never seen this before.
I guess the power of the motor spinning the gears so fast right after the initial moment of damage then caused this aftermath damage.
Moral of the story, shim your gears if you are going to use this ZCI motor with a Li-po.

While we are at it:
After waiting a couple of weeks to get some 9mm Solid Metal Bushings in from China, I was finally able to finish this customers gun today.

I chose the ZCI Black Body Piston.
This is what it like when installed.
http://i1266.photobu...zps2f245b2a.png

This in what it looks like now after less than 100 rounds of dry firing.
http://i1266.photobu...zpsadceb275.jpg
I think it is is fair to say I am done with ZCI Pistons.
I have truly never seen anything like this.

For what it is worth.
Set-up.
- MadBull M130 Spring.
- ZCI Balck Body Piston.
- Guarder Ported Polycarb Piston Head.
- X-ring
- Stock KWA 3GX Gears (2gx Spur Gear)
- Full-Tune-up:
1. B/P Shimming.
2. AOE Correction.
A. Added Sorbo.
B. Piston teeth 2 removed, 3rd tooth shaved 50%, 4th tooth shaved down 30%.
3. Zardichar Mosfet.
4. Rewired completely with the wiring that came with the Zardichar Mosfet.
A). Bullet Connectors/Wire,  XT60 Connector/Battery wire and Battery.
5. Cylinder / Cylinder Head Sealant Mod.
A).Polished Cylinder

- Motor: ZCI HT.
- SHS Pinion Gear.
- Battery: Zippy 11.1v/1500mah/35C.

New Set-up:
- System SuperCore Piston.
- G&G Aluminum Ported Piston Head.
- MadBull M140 pring.
- Everything else is the same.

Edited by vanevery, 03 May 2014 - 04:10 PM.





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