V5 motor repair (replacing the DC motor inside)

Does anyone know where to buy just the DC motor part of a V5 motor? The part # is FS28-KD/23125/DV or it is SMC D247x11 as printed on the DC motor inside the V5 motor. That motor is not soldered to the board in the v5 motor and easily pops on and off the board in the V5 motor so it would not be hard to replace it. That is if you could find where to buy it. We are seeing about a 10% failure rate of that DC motor with the busing getting lose inside the motor. (you can hear them rattle around in the DC motor or the motor locks when the busing get stuck in the motor). We are past the warranty on the V5 motor from VEX and looking to save some money fixing the 4 out of the 30 motors we have that failed in the last year.

Here is a motor that is close but it is not the right one
it has 9 teeth instead of the needed 10 teeth for example and the torque and speed might be off

This company looks like they probably made it for the V5 but that exact part is not listed and I don’t think they sell direct to the public.

So if anyone has found out where to buy this DC motor please list it. Or better yet VEX should sell just the DC motor as a repair item like they sold the gears for the 393 motors. These DC motors are failing just a fast as the gears did. It doesn’t mater to me if the motors are leagle or not after the fix at this point. I just rather spend $10 instead of $200 fixing the 4 of them.

Thanks for the help.


It is illegal to modify electronics. Even a motor that is seemingly identical could give an unfair advantage, and therefore, you can’t do that.


That this would not be competition-legal is a good point, and my first thought as well. However, original post did indicate at the end that it doesn’t matter if the motors are illegal after the fix. Presumably, they are either for classroom / personal use or will be clearly marked as ‘for testing and not for competition’ use. Hopefully, using an after-market motor won’t affect the V5 brain - maybe @jpearman could verify (he’s my 1st guess as to someone who may have insight into this). My 2nd guess would be @V5Wizard, who did an impressive analysis on the broken ports issue.

Unfortunately, if you haven’t been able to find it available for sale with all the information you have it is likely Vex-specific. You might consider sending an email to the Vex tech support and seeing if they have any additional information, if you haven’t done so already. Maybe you’ll inspire them to sell it! :slight_smile:


The motor is custom built to VEX’s spec, you may find similar motors, but free speed, torque etc. will be different.


Your best bet may be to find nearby teams with dead motor electronics and good motor parts and then combine good parts from each.

Then you could have half as many fixed motors, but they are going to be competition legal.


This would still not be competition-legal.

Edit: See below

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Replacing the motor is then just as legal as replacing screws or moving cracked base from one motor to another.


I verified for myself that the DC motor inside a V5 Smart Motor is indeed replaceable through strictly mechanical means (12 screws and the motor can be pulled right off its protruding contacts on the PCB), so there is no contention there.

While I began writing this post to justify my inclination to call this repair illegal, after carefully rereading the relevant rules, I am no longer convinced that it would be illegal.

However, I would still like to see an Official Q&A ruling on this if any team intends to actually use this repair in competition.

Relevant rules
<R21> No modifications to electrical components are allowed. Motors (including the internal PTC or Smart Motor firmware), microcontrollers (including V5 Robot Brain firmware), extension cords, sensors, controllers, battery packs, reservoirs, solenoids, pneumatic cylinders, and any other electrical component or pneumatics component of the VEX EDR platform may NOT be altered from their original state in ANY way.

    a. External wires on VEX electrical components may be repaired by soldering, using twist/crimp connectors, electrical tape or shrink tubing such that the original functionality / length is not modified in any way. Wire used in repairs must be identical to VEX wire. Teams may make these repairs at their own risk; incorrect wiring may have undesired results.

    b. Teams are advised to use the latest official VEXos firmware updates, found at www.vexedr.com. Custom firmware modifications are not permitted.

    c. Teams may change or replace the gears in the "2-Wire 393" or "2-Wire 269" motors with the corresponding official VEX Replacement Gears

    d. Teams may change or replace the gear cartridge in the V5 Smart Motor with other official replacement gear cartridges.

<R22> Most modifications and repairs to non-electrical components are allowed. Physical modifications such as bending or cutting are permitted and may be done to legal VEX Robotics Competition metal structure or plastic components.

    a. Physical modifications to electrical components such as a legal microcontroller or radio is prohibited unless otherwise explicitly permitted, per <R21>.


The relevant rule (other than common sense) is R5. You can’t say you’re “using official VEX EDR components” and change out some internal component to a non-VEX EDR component. Even if you tried to stretch the rule, specifically R5d, a “replacement” motor would have to be identical, and @jpearman has specifically said above that the DC motors are custom made for IFI; therefore, you will not be using an “identical” motor under R5d.

I agree, it would be nice for VEX to sell official replacement motors, replacement motor caps, and even the nylon output gear, since all are mechanical, rather than electrical, repairs.


U can turn a broke part(under certain circumstances) into vex and they give u free one
Those certain circumstances being malfunctioning or burnt out. Now if u drop ur controller and crack screen then they wont do it

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If you take 2 dead V5 Smart Motors, one with a dead chip and another with a dead DC motor, you can combine their components into a single working V5 Smart Motor, using nothing but official components that came from VEX.


True…mixing up parts from two VEX motors into one would present no problem. But swapping out a motor for a non-vex replacement is what the OP was discussing.