Neo 550 motor shaft diameter too small

Last night, when setting up our new Neo550s for our intake, we discovered that the press fit GT2 pulleys were able to press on VERY easily (with one hand). Holding the bell of the motor, we were able to spin the pulleys on the shaft easily by hand.
After measuring the shaft diameter and pulley bore diameter I went to REV’s website to compare the measurements to their drawings. That’s where I found this note:

We used some sleeve retainer that we had (unfortunately not one of the ones recommended by REV) and after sitting for about an hour the pulleys were no longer able to spin around the shaft. Hopefully this solution stands up to use/competition.
I have not seen anything about this issue here, or any communication from REV to teams that may be affected. So, I figured I would make a post to raise awareness of this potential problem for teams.


Had the same problem using 57 Sport Gearboxes with the pressed on pinion gear. Trying to figure it out since only some of them seemed to have the problem. Wasn’t sure if it was the gear or the motor. Found a similar note on the Andymark site for the motors.


The best solution we have found to this problem is welding the shaft to the versa planetary female adapter. I’ll attach a picture of the two pieces we use here and try to grab a photo of one in our shop later. Just don’t forget to put the plastic mounting plate on underneath it.

@NAellen There have been a couple threads and posts about this and we added information to the product page as soon as we found out that this was an issue. If you are still having issues getting pressed on items to stay on NEO550 after using retaining compound, please email our support team [email protected] We have an internal method we can use to help team pre-press items on these shafts by adding a pressed on knurl in our shop.

@Yugmi we do not recommend welding anything to the NEO550.


Greg, Thanks for your reply. I must have missed the threads and posts about it. I know that my team would have benefitted from an email or other direct communication letting us know that we should be on the look out for this problem. We didn’t have much need to return to the product page after buying our motors last fall, that is until last night.
Is your internal method something that a team could replicate?

We used a bit of retaining compound and we have not had issues with our undersized 550’s. We will be more than happy to report back after the week 0 event on Sunday.


Just an update:
We had JB welded our 12t belt pulley to the neo 550 shaft. We thought we had a good solution to the small shaft. We were wrong. The first ball we tried to intake from the field caused the shaft to start free spinning inside the pulley. We went out and get some green Loctite, but it didn’t cure before the end of the event. We hope this will solve the problem. We have our first event in 6 days.

I had wondered about sanding the shafts to add a bit of surface area for the loctite to grip. We couldn’t get green to work for us (though it did last an hour or two) and Rev helped us out with their in-house fix. Hope to receive them back soon.

I am going to post a “quick and dirty” fix that teams can do if they find the Loctite isn’t working (which from feedback has only been in direct pulley on motor situations). Please only do this process after you have tried Loctite.

You can Crimp the motor shaft with an Anderson tri-crimp tool, it will create a ridges that allow for press-fit. This is similar to the way knurling works where some part of the metal goes inwards which causes other parts to grow.

We have tested this in our shop and it does work well, but please note that Loctite is still the best solution.
NOTE: This will dull the small sharp point on the crimper, which might impact the quality of crimps for Anderson Power Pole Terminals

The first position on the tri-crimp is the one to use.

Take the neo550 shaft put it in the first position and perform a crimp. From our testing, a single crimp is all you will need. You will then be able to press-fit any of the standard items on the NEO550 Shaft.

We have done some basic testing, on concentricity and motor stalling without any issues of performance.


Greg, Thank you for sharing this method. I think it will be particularly useful in a case where you don’t have time to wait for the loctite to fully cure. Like if the loctite breaks between between matches. This makes me feel much more confident going into competition season running the Neo 550s.


we completed the operation last night. I crimped the shaft and didn’t see or feel any deformation to the shaft, so we did it again. I tested the fit on our 12t pulley and I couldn’t slip it on! We added a bit of green Loctite and pressed the pulley on. We are waiting until Wednesday to test it, but it looks promising.

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REV does have this Gear that works prefectly with the NEO550 (you’ll need to buy the Pinion to mount into this separately though). This has a special 0.5" Hex adapter that you can use with this that you can purchase separately as well. Unfortunately they’re currently out of stock, maybe you can find a local team to you that have some spare stock?

I haven’t looked at their latest gearbox (MaxPlanetary?) but I would suspect that would also work too.

For what it’s worth, I’m pretty sure the shaft coupler you’ve circled here is the AM 9015 coupler, not the 550 coupler. Mixing those up has been the source of several couplers coming loose of the motor shaft for us. Make sure you put on the right one!

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I had success today using a small strip of .001 shim material that we had on hand. We did not have any suitable Loctite on hand. I know that this will result in a permanent press fit, but that is better than the pinion slipping during use.

Would you please share what this is? I was searching for something like this a while back & didn’t find anything that thin. Thanks

what is the date code on the motor? please send an email to [email protected]

They were the 202109 Date Code. They were purchased last summer in preparation of our rookie season. I will send an email.

The small shaft on that date code is a known issue on the product page. We recommend using Loctite 21448 Green 638 High Strength Retaining Compound

You can also use a wire crimping tool to put a mechanical divot in the shaft which will help as well.

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Not sure if this is exactly the same as what I have, but is functionally the same. From McMaster Carr – McMaster-Carr

Mine is Mauldin Products P/N M31612-1-M, SS316, .001" x 8" x 12"

We have used it in FTC to remove “slop” between hex shaft and sprockets.

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