Need help removing covers from a 9C motor.

I'm trying to remover the covers on a new (flat sided) rear 9C motor, I got it from Grin a few years ago. I want to drill some vent holes to aid in cooling.

I've taken out all the screws on both sides.

On the brake side I was able to loosen the plate and move it out about 1 1/2" but it seems to be meeting some sort of sharp resistance. I don't want to use much force as these sides can be fragile I've read. Maybe it's just a burr that it needs to get past?

On the geared side I have a single free wheel sprocket, I assume this can be left on. I can not get that side to budge. Do most folks use a thin putty knife to break them free? This side has white stuff (liquid gasket?) between the cover and the main motor.

I don't want to force anything and crack a cover. It seems like these should be fairly easy to remove.

A thread from earlier this week has some people trying to help someone else with this issue, with links, etc.

Just don't ignore them like that person did.

I searched for something here but only found one post with the guy who cracked his side cover. The links seemed to only go into removing cassettes, not for removing the covers. I'll look again...

Ok, from a link from a link in that post I got this pdf from Grin:
https://www.ebikes.ca/documents/HubMotorStatorRemoval.pdf

It more about separating the stator and rotor from each other but is helpful I suppose. Am I wrong in assuming I can simply remove both covers and leave the stator essentially in place?

How the covers come off kinda depends how tight the bearings grip either the axle or housing. Sometimes the bearings stay in the housing cover and other times the bearing stays on the axle. I've seen it both ways although I suspect the correct way is the bearing remaining in the cover but remember this is old world craftsmanship (sweatshop) we're usually dealing with.

I've never used a gear puller yet and if I did I would never, ever "crank it down" as the puller should merely help overcome magnetic force. I start with a sharp putty knife and then move on to a butter knife and sometimes bigger and bigger pry tools working around the cover evenly prying up.

If you're able to remove the brake side cover 1-1/2" using a flashlight you should be able to see if there's anything unusual inside? Most likely you're hitting a burr or spot on the axle.

I once had a difficult one and rigged up a way to basically hang the motor by loose cover while tapping on the axle with axle nuts until it dropped through catching itself on the axle nut.

If the axle is not sliding through the bearing like it should I would apply a little oil. If you can get the cover off part way I would slip in two long bars to support the cover at the bearing and then tap the end of the shaft with a hammer to drive it through the bearing. That will likely wreck the bearing, but it's a good idea to replace them with quality items anyway. The important thing is to avoid bending stress on the covers.

Lots of ways to pop the cover off that axle, and nothing wrong with some penetrating oil if really stuck.

But if you don't have a three jaw puller, you should go get one. In my country, you can go borrow one free at car parts stores. Or buy one cheap at a place like Harbor Freight.

A puller is best, doesn't jam the axle crooked damaging the bearing.

Thanks for the help. I got a thin putty knife and pried the one cover off. Easy peasy. The other I couldn't get past the burr but was still able to mount the cover with the stator still attached to my drill press and put some holes in.

I didn't think about how much louder the motor would be with the holes in the covers. Seems about twice the noise level.

A bit off topic but maybe a learning moment about the noise of hub motors? When you look at it, the housing attached by spokes is sorta like a bell. Particularly, those little geared motors - Q variants. I've got one with a cassette freewheel that rubs/catches every once in a while - the sound resonates like the motor is completely destroyed inside. But no, it's just how the housing assembly loudly resonates suspended by spokes.

As far as cooling holes I don't bother anymore. Why weaken marginal strength cover? It does support the bearings, ya know... I realize it's a very common mod but if I need better heat handling capability I'll choose a different motor.

I will put a small 1/4" hole in each cover for possible drainage and inspection. Covered with tape majority of the time.

Quality control ? I amazed how cheap these motors are think how cheap you can buy them if you bought a thousand at a time. I have a roll of emery cloth firm h.f. cheap prefect to help fine the blur, if it has pne. Nothing wrong with a drop of oil. Yea I have a broken side cover. Not very strong.

dogman dan said:

Lots of ways to pop the cover off that axle, and nothing wrong with some penetrating oil if really stuck.

But if you don't have a three jaw puller, you should go get one. In my country, you can go borrow one free at car parts stores. Or buy one cheap at a place like Harbor Freight.

A puller is best, doesn't jam the axle crooked damaging the bearing.

Click to expand...

I just got an 8 inch one at Oreilly's. 18 bucks plus tax. Seemed like a good deal.
otherDoc