Are inner axle washers on a hub motor necessary?

[VvZJw]

https://www.ebikeschool.com/install-hub-motor-washers/ talks about the axle washers, but my front hub kit didn't include any and the hub fits pretty snug in the fork. Is it worth going to the hardware store and grabbing some, or am I fine to skip them?

For context, it's a rigid steel front fork

 

[mclewis1]

If you are talking about "regular" thin flat washers that would simply behave as a bit of a spacer then no, not having then isn't likely to be an issue (assuming everything like the disc brake rotor lines up properly and nothing is rubbing). But if you are talking about tabbed washers that are used to add to the anti rotation capabilities of the axle flats then yes they are a good idea, particularly good solid ones like those from Grin (ebikes.ca). The stamped ones are helpful but less so than the others ... the better ones are often thicker and also fill in more of the dropout opening meaning less back and forth rotation.

 

[VvZJw]

Yep I'm talking about a regular thin flat washer, a plain flat donut. Something I could find at any hardware store. Everything is lined up with no rubbing, so I didn't think it was necessary but I wanted to be sure. The kit did come with what I think you're talking about (labeled a "torque washer" in that ebikeschool link) and I have those between the nut and the dropout, and I've got a grin torque arm on one side and a cheap one that came with the kit on the other side, so I think I should be good

 

[mclewis1]

That all sounds good. As long as it all fits snug without interference (and remember that the fork will compress a bit when the nuts are tightened) you'll be fine. I've experienced this - dropping a motor into the forks sitting upside down, everything looks good and then having a small issue when it was all really tightened up and turned over. Where I think folks sometimes get into trouble is with very rigid forks and there's a gap left to the side of the axle/motor mounting.

 

[tomjasz]

All hub motor builds I've done require washers between the dropouts and hub shaft. We took a lot of support calls from builders with binding wheels and kits without needed washers.

Front forks with quick-release hubs benefit from the use of C washers.

Stainless Spacer C Washer to clear quick-release lawyer lips.

Link> Several sizes and other types are shown here.

• Fits inside quick release lawyer lips on front forks