TSDz2 brass gear whining

[Btypark]

Hi All

Not sure if this is a common problem or maybe not even a problem but having changed to a brass gear cog, I cant help but be quite self conscious when I set off on my commute. The motor is properly loud for the first 5 minutes under any significant load. Lots of torque initially which seems to then dwindle slightly along with the whirring/humming sound. Thereafter I'm pretty sure I'm not getting the full motor power for the rest of the journey (10 miles)
Same issue happens from every cold start. Does anyone have an insight into what might be going on here? More grease necessary? Something else I cant think of or should be looking for?

Thanks guys!

[Alfie]

My brass gear is noisy until it warms up. Especially on a cold morning. Not noticed any lack of power though.

[Btypark]

Interesting. Can I ask though - is it noisy enough that people in the street will turn around to find the source of the high pitched whine?!

[Hillhater]

Interesting. Can I ask though - is it noisy enough that people in the street will turn around to find the source of the high pitched whine?!

Well, mine is for sure !....but it was with the blue gear also .
Also my roller clutch in the brass gear just destroyed itself, so i replaced it, regreased all gears, ...and it still whines !
I suspect it is the motor/controller ?

[Btypark]

Maybe... I just wondered why the noise on my motor dies down along with the torque assist. Perhaps it's more psychological than real but it definitely feels less oomph (technical term) Than my Bosch sport cx bike over prolonged usage

[Hillhater]

The reduction in power (omph ) is likely the result of battery voltage drop..( sag under load ,and voltage reduction as capacity is used) .
How much this is noticed will depend on the individual battery spec, capacity, chemistry, age, etc etc.
A fully charged pack will feel more “pepy” initially than it does after that top 5% of capacity is used.
The volt drop with Capacity reduction is not linear , with the first 5-10% of voltage dropping much faster than the next 20%.

[Btypark]

This makes sense. Its a high capacity battery but it's made up of Chinese cells. Short of stopping and recharging to the max every two miles I guess it's something to live with.

[Alfie]

Interesting. Can I ask though - is it noisy enough that people in the street will turn around to find the source of the high pitched whine?!

No it’s not that noisy. The original nylon gear was absolutely silent.

[Btypark]

Hmmm - something not right then - I guess I need to open her up an have a look inside...

[Alfie]

What software are you running? I found when I installed the Mbrusa software there was a marked improvement in motor noise.

[fletchro]

I worked at a gear manufacturing company. I took a course on detailed gear design. Noise was one of the topics. We didn't study it in depth, but I remember several factors that influence noise. They are ratio, pitch, and face contact ratio. Really high ratios (as found in the TSDZ2) are bad (partly because they reduce the face contact ratio). Also, ratios that are very close to integers are bad, like a gear set with almost exactly 1:2 ratio. We should also include pressure angle if we're talking about pitch. You can make a gear set quieter by changing the ratio slightly or making it wider (face contact ratio). But here's the main takeaway: unless you are designing the gear set (and the container for it), there's almost nothing you can do about gear noise. After it's designed, all you can do is keep it properly lubricated. You have noise because metal is touching metal at a certain frequency == sound. The plastic gear is quieter because it absorbs some vibrations as it hits. Sorry. You will probably always get more noise with the brass gear.