Motor wire detached--how do I fix it?

[ridgehead44]

So, one of the motor wires detached from the motor. This is a Hobbywing EZRUN 4990SD. It should be an easy solder fix, but how do I remove the plastic casing to reattach the wire? Many thanks in advance for any advice!

 

[Ritz413]

So, one of the motor wires detached from the motor. This is a Hobbywing EZRUN 4990SD. It should be an easy solder fix, but how do I remove the plastic casing to reattach the wire? Many thanks in advance for any advice!

View attachment 274323

I might be more curious why it would have gotten so hot as to unsolder itself...really aggressive gearing?

 

[Ramp addict]

You have to be good at soldering to get those big wires to stick. If you're not really confident with a soldering iron I would recommend buying a new motor instead.

You access the solder tabs by removing the end cap on the motor. There on the inside of the motor. There will be resin covering them. You need to remove all the resin on all three wires. Unsolder the offender and solder the new wire in its place. You'll need to re-insulate the tabs or the motor will short out when it gets wet. It's an involved process and not for everyone.

 

[RustyUs]

Is the motor within the warranty timeframe, and doesn't fall into any of voidable conditions?
If not, then I'd have to open 'er up and investigate... see if it's something you want to tackle.

Post in thread 'Anyone here have experience with replacing capacitors on an ESC? I have a HW Max5 G1 with dented capacitors.'

Mar 23, 2026

Yeah, I took the top part off and realized there is no replacing them. I guess I'll see what the trade in program is like.

I'd be curious to see that as well. I've heard the program giving a person 50% off, most likely from MSRP, and you are paying shipping both ways once you get the return authorization. The thing about it is, they make the program (TryOut / Trade-in program) harder to find. It's like they don't want to make it known. There are no big bold letters mentioning of the trade-in program anymore... you have to use their search engine, or...

• RustyUs

 

[CreepyQuarryCrawler]

I have successfully completed a repair like this back in the day to a Tenshock motor.

The descriptions are accurate, you'll have to disassemble the motor, removing the plastic/rubber surrounding the wires.

You need a pretty powerful soldering iron/station due to the gauge of the wires involved here and the fact your soldering right to the motor windings.

You want to come in with a really hot iron and do it fast.

After I completed the soldering portion I pumped hot glue into those areas to seal it up and insulate the wires again.
It wasn't pretty but I completed that race season on it and am still ripping on that motor today

 

[RustyUs]

You have to be good at soldering to get those big wires to stick. If you're not really confident with a soldering iron I would recommend buying a new motor instead.

You access the solder tabs by removing the end cap on the motor. There on the inside of the motor. There will be resin covering them. You need to remove all the resin on all three wires. Unsolder the offender and solder the new wire in its place. You'll need to re-insulate the tabs or the motor will short out when it gets wet. It's an involved process and not for everyone.

I hope I never get to this point, but... Any solvent/product that you know of to make the resin removal easier?

 

[ridgehead44]

Thanks for the advice, everybody!

I might be more curious why it would have gotten so hot as to unsolder itself...really aggressive gearing?

I was running a 19t pinion. I understand that's kinda tall, but I didn't think it would be so aggressive to make it hot enough to un-solder itself. After the run the motor felt warm to the touch but it didn't burn my finger. Maybe internal temperatures were higher?

Is 19t a bit too much? How about dropping down to 17t? Does that sound better?

 

[CreepyQuarryCrawler]

Thanks for the advice, everybody!



I was running a 19t pinion. I understand that's kinda tall, but I didn't think it would be so aggressive to make it hot enough to un-solder itself. After the run the motor felt warm to the touch but it didn't burn my finger. Maybe internal temperatures were higher?

Is 19t a bit too much? How about dropping down to 17t? Does that sound better?

I highly recommend grabbing a temp gun.
It doesn't have to be something RC specific, places like Harbor Freight have them cheap.

That being said, if you could keep your hand on it then it most likely wasn't that hot. It's possible it was a bad joint to begin with and physically broke away.

 

[Ritz413]

Thanks for the advice, everybody!



I was running a 19t pinion. I understand that's kinda tall, but I didn't think it would be so aggressive to make it hot enough to un-solder itself. After the run the motor felt warm to the touch but it didn't burn my finger. Maybe internal temperatures were higher?

Is 19t a bit too much? How about dropping down to 17t? Does that sound better?

It sounds different....but the rest of the equation is missing. Spur size, internal gearing. Try this...https://www.sodialed.com/utilities/rc-gear-ratio-calculator
if its a common car there is a box for that and it will auto fill the stock values .

 

[WRM]

It sounds different....but the rest of the equation is missing. Spur size, internal gearing. Try this...https://www.sodialed.com/utilities/rc-gear-ratio-calculator
if its a common car there is a box for that and it will auto fill the stock values .

Edited/deleted - "Nevermind" (I read the instructions).