Anyone ever bend a wheel? Or is the axle the problem?

**sgtp** · 11th August 2010, 15:11

Hello all....here is my stupid story.

I started hearing a noise from the rear axel on my little 50cc scoot, so I checked it out. I come to find out that the big, huge, 21mm, most likely largest nut on the whole scooter came loose. The nut holding the rear wheel was 2-3 turns away from being finger tight! The whole wheel was loose on the axel. I tightened it up, with the intention of lock-titeing the nut later.

Today, I go and take another close look only to find what appears to be a nice wooble in the wheel.

It looks like I bent the wheel. I suspect it could also be the axel, but I have not removed the wheel yet, and am not sure how easily I can check the axel to be true.

Has this ever happened to anyone? The thing is, you would never know there is a wooble unless you spin the wheel while the scoot is on the center stand. Being a sub 50km ride I'd like to think the wooble can be ignored if its not noticable, so set me straight if I am wrong.

**bogan** · 11th August 2010, 15:16

Originally Posted by sgtp

Hello all....here is my stupid story.

I started hearing a noise from the rear axel on my little 50cc scoot, so I checked it out. I come to find out that the big, huge, 21mm, most likely largest nut on the whole scooter came loose. The nut holding the rear wheel was 2-3 turns away from being finger tight! The whole wheel was loose on the axel. I tightened it up, with the intention of lock-titeing the nut later.

Today, I go and take another close look only to find what appears to be a nice wooble in the wheel.

It looks like I bent the wheel. I suspect it could also be the axel, but I have not removed the wheel yet, and am not sure how easily I can check the axel to be true.

Has this ever happened to anyone? The thing is, you would never know there is a wooble unless you spin the wheel while the scoot is on the center stand. Being a sub 50km ride I'd like to think the wooble can be ignored if its not noticable, so set me straight if I am wrong.

getting run over at 50kmhr is still likely to be lethal, so sort that shit out otherwise it will get worse, bad enough and it will cause you to fall off.

spin wheel independently from the axel to figure out which one is causing the wobble.

**cowboyz** · 11th August 2010, 16:18

Im thinking collasped wheel bearing right off the top of my head. Really cheap and easy to fix. and you really want to get this fixed like now!

**Jantar** · 11th August 2010, 17:48

Originally Posted by cowboyz

Im thinking collasped wheel bearing right off the top of my head. Really cheap and easy to fix. and you really want to get this fixed like now!

+1. Sounds like the wheel bearing collapsed first, allowing the axle to lossen.

Fortunately its not an expensive repair. You can do it yourself in about 1/2 hour. Just remember to apply grease to the new bearing before fitting it.

**danchop** · 11th August 2010, 21:38

most rear wheels on scoots dont have axle bearings

**vindy500** · 11th August 2010, 21:59

This you bro?

**cowboyz** · 12th August 2010, 03:45

Originally Posted by danchop

most rear wheels on scoots dont have axle bearings

is this true? how does it go round and round? My pushbike has wheel bearings!!!!!!!!!!!

**danchop** · 12th August 2010, 10:16

Originally Posted by cowboyz

is this true? how does it go round and round? My pushbike has wheel bearings!!!!!!!!!!!

well they do but not in a sense of normal bike wheels,the rear rim usually is fixed to the axle by a biig spline and the axle has a very big bearing in the the rear drive casing,theres no bearing located in the rear rim itself

**cowboyz** · 12th August 2010, 10:30

Originally Posted by danchop

well they do but not in a sense of normal bike wheels,the rear rim usually is fixed to the axle by a biig spline and the axle has a very big bearing in the the rear drive casing,theres no bearing located in the rear rim itself

oh.. ok.. well I vote for that one being fucked then.

**bogan** · 12th August 2010, 11:15

Originally Posted by cowboyz

oh.. ok.. well I vote for that one being fucked then.

yeh, does seem pretty likely, more stress on the bearing in a SSSA design, they do look way cooler though

**Spearfish** · 12th August 2010, 18:21

Two up jumping off curbs can bend the little axle, its only supported on one end.
If the shaft is bent the gear oil seal could be fooked as well, contaminating the drum shoes (if it has drums).

If it just the wheel there are a few on trade me.

**sgtp** · 16th August 2010, 20:35

I took off the wheel tonight to inspect everything, and here is what I found: I found it's incredibly difficult to inspect true-ness of the wheel and axle.

I attempted the best I could to spin the wheel on the handle of a ratchet, and the wheel doesnt appear warped. There definitly are no dents from hitting a pothole, etc. I had no idea how to check the axle without removing it, so I took off the trans case cover and spun the clutch as fast as I could, which obviously is not too effective due to the gear ratio. I studied it as close as I could but could not see any noticable wobble. Not knowing what more to do, I put the wheel back on and spun it with my hand...I am not seeing any wobble.

At that point I am starting to think I hastily tightened up the axle nut last time and did not seat the wheel just right, so I put everything back together and start the engine to let the wheel spin while on the center stand. Not untill then do i see the wobble.

By my estimation, there is roughly a 5mm wobble from side to side. Perhaps this is within tolerences of crappy chinese scooter build quality? I dont know.... I wouldnt mind replacing the bearing that the axle rides on, I just dont look forward to having to remove it completely just to find out what size to order.

**bogan** · 16th August 2010, 20:41

sounds like an unbalanced wheel with a worn bearing, if you try and move the wheel in the same way its wobbling by hand will it move at all?

**Spearfish** · 17th August 2010, 12:56

Originally Posted by sgtp

I took off the wheel tonight to inspect everything, and here is what I found: I found it's incredibly difficult to inspect true-ness of the wheel and axle.

I attempted the best I could to spin the wheel on the handle of a ratchet, and the wheel doesnt appear warped. There definitly are no dents from hitting a pothole, etc. I had no idea how to check the axle without removing it, so I took off the trans case cover and spun the clutch as fast as I could, which obviously is not too effective due to the gear ratio. I studied it as close as I could but could not see any noticable wobble. Not knowing what more to do, I put the wheel back on and spun it with my hand...I am not seeing any wobble.

At that point I am starting to think I hastily tightened up the axle nut last time and did not seat the wheel just right, so I put everything back together and start the engine to let the wheel spin while on the center stand. Not untill then do i see the wobble.

By my estimation, there is roughly a 5mm wobble from side to side. Perhaps this is within tolerences of crappy chinese scooter build quality? I dont know.... I wouldnt mind replacing the bearing that the axle rides on, I just dont look forward to having to remove it completely just to find out what size to order.

This will sound reckless to someone who rides bikes but..
little scoots mostly don't balance their wheels in the moped class and around 2-3 mill wobble at the speeds moped scoots travel at will hardly be noticed if at all. Some cheap scoot tyres can have as much wobble as that.

Its one of the big problems when you start modifying them to run over 100kph.
As crazy as it sounds polini have released a cylinder/crank kit that fits onto a 50cc case that will push out up to 33hp from its 90cc displacement, probably time to start worrying about wheel run-out then. LoL

**motorbyclist** · 21st August 2010, 17:47

What make/model/age is the scooter?

Chinese scoots have super-flexible (ie super-cheap) chassis and I wouldn't be entirely surprised if a new or near new one had the same wobble. You say you don't notice it while riding so it could be the case.

The easy way to check would be to find another of the same age/model and see if it has the same problem.

Can you post up photos of the axle and the wheel? I'm interested in the wheel hub from both sides.

Once both of the above requirements have been satisfied, someone who has had this problem or has experience could much more readily assess the situation, rather than have random motorcyclists making wild speculations and assumptions without even knowing it's a single sided swingarm with sealed bearings

A few more questions:

If you turn the axle, does the tip wobble? (maybe run the motor, carefully)

Is there any play in the axle?

When you spin the wheel (bolted on), is it smooth, or rough/rumbly/gritty? Rumbling indicates bearings instantly)

I doubt a loose axle nut would damage the rim, but there's no real way to check without fitting it to a non-wobbly shaft. For all we know the hub was never bored true and is at a slight angle to the rim!