V8F stuttering vibration under forward acceleration

[Mono]

After a mileage of close to 7000 km I get this stuttering vibration only under forward acceleration or backwards deceleration:

 

I checked and tightened (where applicable) loose screws of the

• control board
• shell on the hangers
• axle

To no avail. No cracks in the shell, as far as I can tell. The wheel diagnostics via the app doesn't indicate a problem too.

One of the 24 screws around the rim that fix the motor can't be tightened.

I found these two related threads

but still don't have a good grasp on the cause of the problem.

Control board? Hall sensors?

Edited March 12, 2023 by Mono

[mlau]

Mine did that as well after ~250km.  Then one day, after turning it on, it started doing that and didn't stop until it broke the axle, damaged some wire(s) and finally only said "Please repair".
I was never told what caused it, but repair was expensive (not covered under warranty), cost almost as much as a new one.

[Denny Paul]

I have some experience having seen this exact problem with this exact wheel. The culprit was the main bolt that secures the pedal hangers on to the motor axle causes problems like this the most frequently on Inmotion wheels. For some reason, they haven’t been cinching them down hard enough, or perhaps not using the right thread locker.

This is the biggest bolt on the euc. It requires dropping the motor out, red loctite, and then applying a lot of leverage using two wrenches (one on each side to prevent it from spinning).

Edited March 10, 2023 by Denny Paul

[mrelwood]

If the axle/pedal hanger bolts are tight, it is possible that the axle has cracked. I had one case like that.

 When the motor is out of the shell, press with your whole sight from left pedal’s front edge and the right pedal’s rear edge. Then swap, left pedal’s rear and right pedal’s front.

 If the pedals move separately (against each other) at all, the axle has probably cracked.

[Mono]

On 3/10/2023 at 6:03 AM, Denny Paul said:

I have some experience having seen this exact problem with this exact wheel. The culprit was the main bolt that secures the pedal hangers on to the motor axle causes problems like this the most frequently on Inmotion wheels. For some reason, they haven’t been cinching them down hard enough, or perhaps not using the right thread locker.

This is the biggest bolt on the euc. It requires dropping the motor out, red loctite, and then applying a lot of leverage using two wrenches (one on each side to prevent it from spinning).

I can't move the axle nuts at all using an 18cm long lever.