Whining Transmission (Sym Mio 50cc) By vacious (Read 1,866 times)

[vacious]

While unsuccessfully trying to locate/resolve another issue, my Sym Mio developed a whining noise from its transmission.  Some background info : 

1. Mechanic took transmission apart to try and see if it was the cause of another problem.  No damage was found (bearings and gears all in good condition).
2. When i collected the scooter it developed a whining noise after a few km of use (similar sound to the gearbox noise when a car reverses) 
3. I returned it to the mechanic, he also heard the noise, again took apart the transmission but couldn't find any cause (bearings and gears still look fine).

Does anyone have any ideas on what could cause this?  
Could this be dangerous? (lead to a transmission lock-up etc)

[jct842]

Could be the trans is running dry due to coming apart and not putting the oil back in it. check that it has lubricant in it.

[vacious]

The oil level is fine - He drained and refilled to be sure.

I'm wondering if a gear could have been inverted, taken out and put in facing the other way?

[cyborg]

i doubt anything in there can be put in "backwards",,,he may have put a shim in the wrong place or order,,they are hypoid gears to be quiet,,,straight cut gears howl badly ,,,put 2-3oz of lucas gear oil stabilizer in the case to see if it quiets it down

[vacious]

Thanks! Will try and source some and give it a go - Should i drain 2-3oz of oil before adding the same amount of stabilizer?

Was listening to it carefully this morning - It only whines when under load (louder on hard acceleration, silent when coasting), everything moves very freely - Seems odd considering the loud noise.

[Alleyoop]

When things whines it is usually something that is a little to tight especially dealing with gears.

[Guitarman]

Everytime I hear a whine it's a teenaged girl with a long list of complaints. Most often it's because she doesn't think she should have to do the dishes. Try throwing some money at it and see what happens....