V11 knocking noise - solved

[Lex Smith]

Hi folks,

Thought I'd share this in case anyone else encounters it (couldn't find a post that mentioned this exact issue so hoping I'm not doubling up).

At about the 200 km mark my V11 developed an annoying knocking noise.  Initially it was pretty random though only happened when my weight was predominantly on the right side of the machine.  As time went on it got more regular until it kept time with the wheel revolutions i.e. the faster I rode the quicker the knock.  It was a double tap, sort of 'dik dok . . . . dik dok . . . . dik dok".  Other than the noise the wheel rode fine.

At the 460 km mark while out on a ride the bearings gave up the ghost with a harsh metal on metal noise.  I replaced them today with some good quality Japanese bearings and it's fixed the knocking noise as well as the bearing noise.  My suspicion is that excess play in the bearings was allowing the motor rotor to touch the outer ring of magnets in the rim (I could see a couple of wear points).

Anyway the wheel feels the best it's ever felt with the new bearings.

The bearing ID is 6816-2RS (I understand the 2 RS denotes 2 rubber seals i.e one each side).

Dimensions of bearing are 100 mm OD, 80 mm ID, 10 mm width.

As an aside there was no evidence of water or dirt reaching the bearings.  The outer seal was clean and dry so I don't think water or dirt getting into the bearings was the issue.  I might crack them open when I get a chance to see what exactly went wrong.

Hope this info proves helpful to someone

Kind regards

Lex

[m365ww]

Hello Lex,

Thanks for posting this useful info for people.  This is an issue I have also experienced a couple times with electric scooters I fixed up.  From this experience and other people I've talked to, the culprit is usually a bad bearing and/or loose wheel cover screw(s).  As you stated, this would allow play where the rotor would eventually contact the stator magnets. 

However, sometimes it could be an oversized bearing bore.  This sounds a bit odd and difficult to picture, but I've experienced this personally.  Once under load, the oversized bore will "knock" the bearings together at the approximate location of the oversized area.  This was fixed by using Loctite 641 bearing retaining compound and was chosen because it was medium strength (still able to remove bearing w/o a torch).  If the any portion of the bearing slides into the bore too easily (finger strength) at room temperature, then that is one indication that it is oversized.  No rotor to stator contact in this case.  This may explain why some "still hear the knocking sound even after replacing with new bearings."

Hope this helps someone as well.

Edited June 29, 2021 by m365ww
Added potential example for second paragraph.

[Lex Smith]

Finally got around to cutting open the old bearings - not too hard to see why they were making a noise :-)

Both inner and outer tracks were much the same on both sides and some of the ball bearings were pitted as well.  Again there was no sign or evidence of the ingress of dirt or water into the bearing itself so my belief is that they were just substandard bearings from the start.  The fact the pitted areas are evenly spaced suggests to me that maybe the bearings had moisture in them while in storage and the damage was done before the wheel had even done a revolution.

Just my musings though at the end of the day.