Moral of the story is do not ignore the deceleration vibration! Over the last year our GEM E2 has been experiencing a vibration after lifting off the throttle. It progressively got worse till one day we hit the gas and it didn’t move. I could hear the motor spinning and trying to push the GEM forward but the nothing. Research after the failure would point to failed motor to input shaft splines. This could have been prevented by dropping the motor, replacing the rubber bushing inside the female motor spline and greasing the joint. This is how I repaired the issue.
The GEM is powered by a GM motor with a female splined coupling on the end. Here is a picture of the splines after failure. You can see the stripped teeth on the top 2/3 of the coupling. They were not as bad as the input shaft but did see metal loss.
This is the male input shaft on the gearbox. Again you can see almost all of the splines have been stripped off.
Step one was to remove the motor, 4 electrical wires, 2 electrical connectors and 3 bolts. Motor slides out easy.
Step two remove the seal on the input shaft. My new input shaft came with a new seal so I butchered my old one.
Step three remove the snap ring and remove the existing stripped input shaft, it should pull out easy. Old shaft is garbage.
Step four is repair existing motor spline. The new shaft did lock in place but with lots of play. This is a link to company who make a kit to repair splines:
Could you do this entire repair with the old shaft? Maybe. But we put a lot of miles on our GEM and I wanted it to last. The repair kit comes with plenty of compound so you could try it that way first and if it failed then order a new input shaft.
Clean the motor side, lube up the new shaft, mix the putty and insert. Sounds easy… not so much. The silicone did NOT release the putty from the input shaft. I had to heat the joint and use ball joint forks to pry the shaft back out after the 24 hr. cure. If I did it again I’d probably use a thicker grease on the input shaft to prevent the repair compound from sticking to it. As a result the top portion of the repair pulled out. Many of the splines did stay and I left it the way it was. Not perfect but good enough. The other problem is the input shaft has a recessed portion on the top that collected compound. I’d recommend not putting the shaft so far into the motor coupling to prevent the problem. That should significantly help the release. I tried to cover the low spots with tape but it wasn’t enough. Make sure to mark the shaft and motor with an alignment mark. It will only go back one way.
Clean up the motor and shaft, replace motor rubber bumper and lube with Honda 08798-9010 MOLY PASTE (M77)
Install motor the same way it came out.
Two weeks on it so far and all good.