Bearing Replacement: Cup&Cone v Cartridge; for Hub Motor

[amberwolf]

This would probably be an impossible mod without some machining, but I'm going to have to replace the bearings in my hubmotors on the SB Cruiser trike; they're getting pretty worn from the sound/feel of things as I ride.

There are two different front motors (in the rear wheels) which complicates things, too: 9C 2807 and Crystalyte X5304.

The reason for considering cup & cone style is that these wheels see considerable side loads, and I don't think the cartridge bearings (at least the ones that come with them) are meant to take those. But cup & cone often do on regular bike applications, and dont' seem to wear as fast (assuming proper greasing and staying clean of grit).

So, assuming C&C vs Cartridge type would be any better, given that whatever I do either way will have to be done with what I have laying around, I think I might be able to do it using old BB cups for the outer races, if I can find a hardened surface that will work for the inner race over the existing axle, without machining and hardening the axle afterward.

Regular bike axle stuff is way too skinny to use on these thick hubmotor axles.

Another challenge is to be able to set the pressure on the C&C because I wouldn't have a threaded axle to put them onto. I'm not sure how I'd get around this.

But if anyone has any ideas, I'm up for pondering them.

 

[amberwolf]

Nobody?

Am I just crazy?

wait--don't answer that...

 

[Lurkin]

Not crazy, just struggling to see it implemented well without machining because the cups will need to be the perfect size.

Hmm. I see your justification re lateral strength... but it's a lot of work when a new is a press in and put job.

Why can't you use the axle threads with longer cone? Hold it there with pressure?

Ideally if you can find a hub with the right sized cups you could Butcher it for them? Note rear hubs use larger size bearing...

 

[amberwolf]

Not crazy, just struggling to see it implemented well without machining because the cups will need to be the perfect size.

Yeah. I can do the machining bit (maybe not very precisely)...but hardening....

Hmm. I see your justification re lateral strength... but it's a lot of work when a new is a press in and put job.

Yep, which is part of why I made this thread to work out the details, and see what better ideas others have. I have lots of ideas, but most of them are not all that good.

Keep in mind that because of total trike width restrictions and whatnot, that once I have time to deal with the issues, these motors wont' have axle nuts to hold them on. If I could, I'd use pinching dropouts on the outer side but I don't have space to do them the way I did the inner ones, and I don't have the tools to do them the "right" way. I have a few other ideas to try but will probably go with what I tried as a temporary test on the 9C motor, which is to weld a plate on the end of the axle stub and clamp that plate to the dropout plate/frame...doing this, though, means I can't just get in there and change out bearings as needed. I have to cut the plate off and reweld it each time.

Why can't you use the axle threads with longer cone? Hold it there with pressure?

AFAIK, I'd have to rebuild the dropouts (and widen the frame they're on) to make them wider to accommodate the hardware. As it is, it's so close to the limit of what will fit thru a doorway that before I cut the outer axle end off the 9C and welded a plate on there instead (which will have to come off to deal with the bearings regardless of which way I do them), I often hit the doorframe on the way in or out of the front room. (presently it's parked in a shed converted to a garage, but when the real heat of summer comes then it'll have to get parked inside the house again on any days I'll be taking a dog with me somewhere, so it isn't so hot that it's unbearable inside before we even begin the ride).

I suppose I could make cones out of axle nuts. Perhaps if I could find automotive lug nuts that fit on these axles, I could machine off some of the threads on the cone side, so it will go over the unthreaded part of the motor axle, leaving enough thread to be securable on the rest of the axle stub.

I have a lathe so I can in theory do the machining part. It's the surface hardening that is the part I dont' have a way to do yet. I'd need to build a little furnace like Thud's to do that bit, and hope the process doesn't mess up the threads.

Ideally if you can find a hub with the right sized cups you could Butcher it for them? Note rear hubs use larger size bearing...

I've never seen any bicycle axle (taht uses cup/cone) anywhere near sufficient diameter to use on these hubmotor axles. I can't machine the hubmotor axles down because they're probably barely strong enough for what I put them thru as it is. :lol:

 

[Chalo]

Cartridge bearings have load ratings. 6000-series deep groove bearings like those in hub motors are rated for about half as much axial load as radial load. That's enough, especially when the bearing is oversized like in a hub motor. 7000-series bearings are of angular contact design, analogous to cup and cone.

The main advantage of cup and cone bearings isn't their ability to withstand greater axial loads, but their ability to tolerate misalignment and flex under load. They have a degree of ball-and-socket type motion available that cartridge bearings don't. That's less relevant to hub motors than it is to normal bike wheels, because their larger axles don't flex much.