Wrecked CIM pressing EVO pinion

We finally got our long awaited EVO shifters and went to pressing the pinion gears on the CIM shafts. Did 7 ok then the 8th one went crunch.
According to AM we have crushed the ceramic plate in the end of the CIM. They say they have seen this about one in one hundred CIMs. So, heads up.

Our options are to pull that pinion and press it on another or take the CIM apart and try to install the ceramic piece from another CIM.
Anybody tried taking a CIM apart and put it back together successfully?


I personally have not, but, in my opinion, you are better off to just get a new one. They are fairly cheap and you can be confident you didn’t accidentally re-assemble the CIM incorrectly, which may cause you much larger headaches once it is in the shifter and mounted on the robot.

I’m assuming 8 CIMs mean 4 for a practice bot. Taking apart the CIM is going to count as modifying it, so if you go that route, mark the CIM so you don’t use it on your competition robot. Not that you’d really want to use it on your competition bot anyways.

Why would disassembling and reassembling a CIM w/ no change count as modifying it? There is no cutting at all, just fasteners.

We also sell the CIM with pinion pre-installed for the hassle free option.

Removing and re-pressing the pinion may not result in the best press fit due to the surface finish of the gear changing when it is removed. If you would like to buy a new pinion you can call and order over the phone, we are working hard to get all the individual EVO parts on the website in the next few days.

Isn’t taking the CIM apart required to install the pinion so that you can press against the back of the motor shaft? I’d be really worried about damaging the motor by pressing against the back of the case.

My initial reaction was that repairs to restore a part to its original specification is legal. Close inspection of R71, part M would seem indicate that repairing a motor to meet the original specification should be legal. However, I find it interesting that the GDC specifically does not list motors in R71.

It wouldn’t be obvious… It would be indistunigishable from a stock CIM.

Just because some teams might do it wrong (on accident or on purpose (which would be cheating)), doesn’t mean it’s illegal for all teams.[/quote]

R71 doesn’t apply to motors. R33 is the rule you want. It only allows for specific modifications. Maybe put the armature and front plate into another CIM? I wouldn’t call that a modification, but then I am not your LRI. :] Probably best to use it on your practice bot.

I am sorry but I don’t understand how taking something apart and putting it together as it was is a modification.

Someone explain how that could possibly be.

The rule’s intent is to avoid modifications of the motor.
The definition of modification is
the making of a limited change in something

If one wants to make the point that by taking it apart and reassembling, as it was, is a change then I would submit that by applying power to the motor you are also changing it… the brushes wear during operation so that is a modification if you want to take that kind of position.

I do agree that this is something that I would not do… the motors are not expensive enough to warrant repair unless you are on a supertight budget… but I don’t see it as something specifically prohibited in the rule

The rule quoted was about legal modifications… not repair…

Well we had so many CIMS laying around it was hard to justify another $250+ for more CIMS especially when the EVO doc did not say there was a chance of damaging one of them.

thinking I would rather pull the back plate off and replace what is broken rather than pull the pinion and replace possibly wrecking another CIM or having a pinion that is not on as tight.
Yes P-bot only.
Do any of you know if that is tricky or not?

Previous years’ Q&As* have said some relevant things. A 2015 Q&A noted that replacing a motor’s wires with longer (presumably equivalent ones) wasn’t legal. More relevantly, a 2013 Q&A said that pulling the motor portion off a window motor and replacing it with the exact same model motor portion of another window motor would be illegal under R33. So at the very least, swapping parts even between identical motors has been ruled illegal in the recent past.

*No previous years rules aren’t directly applicable. But R33 has been fundamentally unchanged for quite some time.

That’s a pretty relevant precedent, so submit a new Q&A or only use it on a practice bot.

If you do decide to take the CIM apart here is what you have to look forward to

(Note, under no circumstances do I recommend doing what he does to the CIM in that video, but he gives a nice tour of the inside)

does not really mater as we will only use it on our practice bot

The number of bad ideas in that video is astonishing.

I cried a little on the inside when I saw the state that motor was in.

@OP: I would just put the pinion on a different, functioning CIM. Whether you do this or modify your current one, you still have at least one dead CIM, and possibly another one that’s illegal for competition.

R33 is viewed as the motors are pretty much to be considered as sacred as the pneumatic parts. The linked video gives a good hint as to the damage that can be done to the brush assembly of the CIM in opening and reassembling the motor. Since damage here could result in very high currents, extreme heat and a potential fire, safety would dictate not taking the motor apart.