Freewheel Came Unscrewed & Nearly Welded Itself To My Frame

[Metallover]

I just got up and running with my new Vector frame, running a Cromotor, Max-E. With a crank and freewheel, but not chain yet..

I noticed maybe a slight loss of power, noticed the motor getting a little hot. It was about to hit 200F so I decided to pull off so it could cool down. I was riding pretty hard so I didn't think it was too abnormal. As I was pulling off, all of a sudden it felt like someone was applying the brakes real hard. The back wheel locked up and I drug the bike off the road.

When I looked down I noticed a little smoke, the freewheel was jammed to the side, and the powder coat was melting off my nice new frame!

What must have happend is the freewheel worked its way loose during the ride, then once it hit the frame it got jammed into it. Stripped all the threads and scraped the frame. The wheel is pretty locked up, but it will spin if you push it hard.

I haven't touched it yet, but I am worried the axle/frame may have been weakened by the heat. Softened? Brittle? All the nuts and bolts siezed? The heat was not on the wire side, so hopefully my axle has less of a chance of snapping later?

You can see the axle got super hot, the axle has the purple tint like a motorcycle's exhaust sometimes gets. I'm pretty sure my motor is fine; it never got above about 200F.

Should I be careful when I take it apart to pry off the freewheel? Might need to heat it back up so the hardware comes loose?



The axle looks kind of like this

before

 

[Punx0r]

If the freewheel remains still when the motor turns then the freewheel will wind itself off the thread. Once it touches the dropout there's a rapidly increasing frictional force that jams it harder and harder against the dropout. I'm guessing that never having had pedal force applied through it, it wasn't anywhere near tight enough to stay put.

I imagine if you undo the axle nut the frame will spring out slightly and release the freewheel - assuming it's not jammed on mangled up motor threads. Either way you'll be able to remove the wheel from the frame to work on it. I wouldn't attempt to heat up anything, as differential expansion of the aluminium frame is more likely to make the situation worse rather than better.

 

[John in CR]

Your swingarm and clamping torque plates are steel, aren't they? If so then you don't have to worry about damage other than the paint.

 

[Metallover]

Everything is Steel, I'll see what happens when I try to take it off. I got the bike to work yesterday and I'm taking a pickup in today to bring it home.

 

[MadRhino]

Doesn't happen overnight. Cheap freewheel, poor maintenance, lots of mileage...

Buy a good one and grease it once in a while. :wink:

 

[teklektik]

If it was hot enough to discolor the axle, then the heat likely melted or broke down the bearing grease - which probably wasn't too good with the abnormally high side thrust being applied. It's probably a rubber sealed bearing and the sealing lips may be toast.

It may run acceptably for some time but I think that bearing just had its life shortened quite a bit...

 

[Metallover]

The bearings were another one of my worries. I will look for a replacement Cromotor bearing, unless it looks like new. I'm guessing a little searching on here will get me one..

 

[MadRhino]

The bearings were another one of my worries. I will look for a replacement Cromotor bearing, unless it looks like new. I'm guessing a little searching on here will get me one..

Easily found locally, easier than finding a good freewheel at the local bike shops.

 

[teklektik]

....unless it looks like new.

It's not a question of how it looks, but how it feels - should rotate smoothly with slight drag when spinning the bearing or case cover on your finger, but in this case that may not tell the whole story. In the end, it might be useful to look at this as 'preventive maintenance' depending on how critical uninterrupted riding is for you....

The size and seal code are stamped on the side. It's a standard bearing. Don't put in a cheap Chinese replacement - good bearings aren't cheap but will make this a one-time repair... (seal type: RS=rubber seal, Z or ZZ=unsealed (steel shield))


There's no downside to the rest of the motor if running it with a semi-poor bearing. If the motor rotates smoothly and doesn't sound like Rice Crispies I'd just work on the other repair aspects without cracking the motor open to get riding ASAP. Then contact zombiess or get the bearing spec elsewhere (post up the question on ES specifically). You can just put the replacement on the shelf or replace it at your convenience on a rainy weekend instead of under pressure if (when) it demands attention.... The really suspect bearing is on the non-wire side so the operation is pretty simple.