Metal planetary gears?

Santacruz · Jun 18, 2015

Hello.
I am new to this forum and have just built a mtb ebike.
36v qq-m128r rear motor. Brushless.hall sensor and geared.
I have read about replacing one or all of the nylon gears with metal ones.
My question is. Where do I get these from.
I can only find replacement nylon ones.
Is it best to replace all three or just one. I am not bothered about noise. Just strength.

motomech · Jun 18, 2015

Not available.
If you are worried about it, buy a spare set of nylons.
As with any geared, especially smaller ones, no jumping, log climbing, etc.

fellow · Jun 18, 2015

My question is. Where do I get these from

You have to custom order it here http://gearsmade.com/ or places like that.
Bear in mind that the noise will probably increase to unimaginable levels. Other idea is to use ATF oil, as it has gear protective film that reduces shock. Not sure if it helps a lot on nylon gears. There are oil additives too:

Motomech: No jumping, is it still the case? I thought that it was the rule few years ago. Is there any documented gear breakage with newer Q100H motors? I know that Xiongda 2 speed had bad batch of gears one year ago...

motomech · Jun 18, 2015

Well, I guess that's up to the rider.
This may sound strange, but when I was off-roading with the MXUS, I could feel the gears flexing.
It's real suttle, but if one is paying attention to them(the gears), you get the feeling sometimes that, "If I hit that any harder, I think something would break.".
Like everything, it's a matter of degree.

Santacruz · Jun 19, 2015

Many thanks for the info.
I will get a spare set of gears and think I will enquire about getting a metal set made.
I have the same type of motor on the front of a 20" wheel folding bike with no problems. But on the back of my 26" wheel MTB it just sounds as if it is straining a bit as I am also running 48v as opposed to 36v on the folding.
I am using it in the Netherlands which is flat, so no jumping or other stunts.

d8veh · Jun 19, 2015

The Q128 uses 2-stage helical and straight-cut gears. You've got no chance of steel replacement. I've never heard of anybody stripping the gears on any of the Q-series motors during use. Are you trying to solve a problem that doesn't need to be solved?

That strained grinding noise is from the commutation, not the gears. If you get a sinewave controller, it will go away. Your motor will become smooth and quiet, so you won't even think about the gears.

Santacruz · Jun 19, 2015

Yes. I guess I am trying to solve a problem that doesn't need to be solved.
For the cost I will get a spare set of gears and hope I never need them.

dogman dan · Jun 19, 2015

If you need that strength to jump your bike, you'll just break the key that secures the gear set. You can't do a lot of hucking with the geared motors. But happily, replacing that key is pretty easy. If the key doesn't shear like it should, then you might wreck the clutch. When you do catch some small air, DONT LAND WITH THE TROTTLE ON. Land it, then get back on the throttle.

If your gears will fail by overheating, you are just flogging the motor too hard up too steep hills, or giving it a stupid level of overvolt or over amps.

In short, if you need that metal gear, the motor is not the problem, you are. If you want to run 2000+ watts, or fly a lot, then you need to go to the direct drive hubmotors that have no gears, and have the magnet size to handle that kind of power. The motor inside the larger geared motors is still really small. It's simply not up to much more than 1500w or so of 48v.

Matador · Oct 4, 2018

dogman dan said:
If you need that strength to jump your bike, you'll just break the key that secures the gear set. You can't do a lot of hucking with the geared motors. But happily, replacing that key is pretty easy. If the key doesn't shear like it should, then you might wreck the clutch. When you do catch some small air, DONT LAND WITH THE TROTTLE ON. Land it, then get back on the throttle.

If your gears will fail by overheating, you are just flogging the motor too hard up too steep hills, or giving it a stupid level of overvolt or over amps.

In short, if you need that metal gear, the motor is not the problem, you are. If you want to run 2000+ watts, or fly a lot, then you need to go to the direct drive hubmotors that have no gears, and have the magnet size to handle that kind of power. The motor inside the larger geared motors is still really small. It's simply not up to much more than 1500w or so of 48v.

Please define "stupid level of overvolt"... I'm just went from 36V to 52V on that small 250W motor that I don't know who makes...
See here: https://endless-sphere.com/forums/viewtopic.php?f=2&t=93576
What would be in the safe zone in terms of watts ? I'm 70 kg. never more than 5% inclines for 500 meter at most in my area...

motomech · Oct 4, 2018

Quite a few years ago, a member here, mckeefer, over-volted a min-motor to destruction. As I recall he was in the 70 to 80 Volts range when the windings cooked. Of course, he had to up the amps as Voltage went up to achieve an increase in speed.
I have run 14S LiPoly (about 54V nom.) on mini motors, while dialing back Amps a little and they survived. Remember, what we are really talking about is power (V X A). My experience was, there is not much point in going any higher in Volts w/ mini-motors, has there is little increase in speed. The windings become saturated.

Metal planetary gears?

Santacruz

100 W

motomech

10 MW

fellow

1 kW

motomech

10 MW

Santacruz

100 W

d8veh

1 GW

Santacruz

100 W

dogman dan

1 PW

Matador

100 kW

motomech

10 MW

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