[HandyAndy]

As a rule, the bearings in EVs are slightly looser-fit in their spacing between the inner race, the balls, and the outer race, i.e. they feel "rattlier" when taken out of the box. Reason is these motors run at high rpms, so you don't want the bearing to be as quite tight as you might if fitting it to, say, a regular mains AC low-speed motor.

Qn then is, did Renault skimp on this, rather than fit a "special" carefully-toleranced bearing designed for continuous high speed running, and did they cheap-out and fit the regular off-the-shelf bog-standard one? Also was it a cheap asian-made bearing, or high-quality eg SKF one?

Getting the correct replacement bearing might not be quite as simple as it sounds.

Also, are there issues with stray electrical conduction routes? With magnets & rotating metal around, EVs seem to have a problem with generating small electrical currents which flow from the rotor to the motor casing, through the steel ball bearings! Not good - the microscopic arcing begins to etch-away the metal, think electric switches/points etc, so there's a need to either use ceramic insulating bearings, or provide something like a carbon brush to earth the Rotor bypass the problem. I don't what approach the Zoe takes. Might need a new set of brushes as well, whatever.

 

[HandyAndy]

Replacing a motor bearing will not be more work that say replacement of a clutch in an ICE car. The bearing will be cheap, assuming it's a standard size, which it would be.

See my post earlier. Hyundai Ioniq 28 sometimes has a well-known bearing problem, usually just the reduction gearbox bit. Some of the bearings are standard. One at least is a Hyundai special, larger O.D. than usual I think. Me? I'd make a sleeve on my lathe & get on adapting something. There is now an after-market kit you can get, phew!

 

[HandyAndy]

Are you sure that the motor bearings are designed to run loose? Normally that is an no no, as if the bearing is loose, the balls will slip and skip, resulting in pitting and burning of the balls or the races...

I think you're correct, perhaps "loose" was the wrong term. "Freer-running" would have been better! Pretty sure I read somewhere about the dimensional tolerances being different for high-speed bearings, maybe any pre-load is reduced fractionally? E.g. see here what SKF have to say about this:
https://www.e-motec.net/customised-...ised-bearings-and-hybrid-bearings-solve-fundamental-issues-in-electric-vehicles