QS 138 70H with Gearbox

General Discussion about large electric scooters and motorcycles and other things with no pedals.
User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

QS 138 70H with Gearbox

Post by dforesi » Mar 04 2021 8:58am

I was browsing some Youtube videos on saw this motor mentioned on a couple channels but I can't find too much information on it:

https://www.aliexpress.com/item/1005001 ... Uad7bRfvkQ

Image

Image

I'm planning out a conversion for a full size motocross bike and thought this could be ideal. The 90H motor seems like it would be better from a power perspective but having something like this would eliminate the need for any type of jackshaft. This could be a nearly bolt in solution as the sprocket location would be ideal as well.

Thoughts?
Aspiring E-builder

Houston, TX

john61ct   100 GW

100 GW
Posts: 7832
Joined: Dec 18 2018 2:06pm

Re: QS 138 70H with Gearbox

Post by john61ct » Mar 04 2021 7:33pm

interesting, want to see the torque curve on that compared to the vanilla one

User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

Re: QS 138 70H with Gearbox

Post by dforesi » Mar 04 2021 9:09pm

It's posted in the Ali link

Gearbox motor:
Image

regular 70h

Image
Aspiring E-builder

Houston, TX

User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

Re: QS 138 70H with Gearbox

Post by dforesi » Mar 04 2021 9:13pm

Looks like you would have to plot some points on excel for both and compare apples to apples. Clearly they are measuring at the shaft in both cases, and the gear box motor has a 2.35 reduction so it makes these two graphs hard to compare.
Aspiring E-builder

Houston, TX

hugok   10 mW

10 mW
Posts: 26
Joined: Mar 05 2021 5:40am

Re: QS 138 70H with Gearbox

Post by hugok » Mar 05 2021 6:06am

I have ordered one but I'm still waiting for it to be shipped since there was a lot of backorders after chinese new year.

User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

Re: QS 138 70H with Gearbox

Post by dforesi » Mar 05 2021 6:55am

Well please keep us updated!
Aspiring E-builder

Houston, TX

Jordan325ic   1 W

1 W
Posts: 58
Joined: Aug 05 2020 6:44am

Re: QS 138 70H with Gearbox

Post by Jordan325ic » Mar 05 2021 8:46am

I have one of these on my bench right now. Haven't hooked it up. My only complaint is that transmission fluid leaked out everywhere during shipping. I'll take photos when I take off the transmission cover plate to fix this.

User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

Re: QS 138 70H with Gearbox

Post by dforesi » Mar 05 2021 9:03am

From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?
Aspiring E-builder

Houston, TX

Jordan325ic   1 W

1 W
Posts: 58
Joined: Aug 05 2020 6:44am

Re: QS 138 70H with Gearbox

Post by Jordan325ic » Mar 05 2021 1:37pm

dforesi wrote:
Mar 05 2021 9:03am
From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?
That was my first thought, but on cursory inspection it appears to be leaking from the gasket/seal face. But I haven't had a chance to investigate.

It will go into a 1974 yamaha dt250.
20210213_165239.jpg
20210213_165239.jpg (3.08 MiB) Viewed 2151 times

Elektrosherpa   100 W

100 W
Posts: 127
Joined: Feb 07 2021 8:19am

Re: QS 138 70H with Gearbox

Post by Elektrosherpa » Mar 05 2021 7:41pm

Now that's "MY KIND" of bike.
Looking forward to see how you'll do it :thumb:

markz   100 GW

100 GW
Posts: 12258
Joined: Jan 09 2014 11:38pm

Re: QS 138 70H with Gearbox

Post by markz » Mar 06 2021 12:38am

I'd like to know the gear reduction, and whats the deal with the keyway on the shaft?

j bjork   100 kW

100 kW
Posts: 1069
Joined: Aug 31 2018 3:01pm
Location: Linköping, Sweden

Re: QS 138 70H with Gearbox

Post by j bjork » Mar 06 2021 5:50am

Jordan325ic wrote:
Mar 05 2021 8:46am
I have one of these on my bench right now. Haven't hooked it up. My only complaint is that transmission fluid leaked out everywhere during shipping. I'll take photos when I take off the transmission cover plate to fix this.
Then you can take the opportunity to photo and measure the gears :wink:
I havent seen any info about if it is spur or helical gears, or how wide they are.
Maybe I have seen tooth count somewhere, but I am not sure.

SlowCo   1 MW

1 MW
Posts: 1784
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: QS 138 70H with Gearbox

Post by SlowCo » Mar 06 2021 8:23am

markz wrote:
Mar 06 2021 12:38am
I'd like to know the gear reduction, and whats the deal with the keyway on the shaft?
Then use the link in the first post...

User avatar
dforesi   10 mW

10 mW
Posts: 31
Joined: Mar 03 2021 12:25pm

Re: QS 138 70H with Gearbox

Post by dforesi » Mar 06 2021 8:26pm

Jordan325ic wrote:
Mar 05 2021 1:37pm
dforesi wrote:
Mar 05 2021 9:03am
From the photos I saw, it looks like there is a pressure release nipple on the case that's held on with a zip tie. I imagine that its not fluid tight. Perhaps that is where it evacuated from?

What do you plan to use it for?
That was my first thought, but on cursory inspection it appears to be leaking from the gasket/seal face. But I haven't had a chance to investigate.

It will go into a 1974 yamaha dt250.
20210213_165239.jpg
Jordan, great project. Where did you order your motor from? I am trying to get one shipped to USA. How long did it take and what did you pay?
Aspiring E-builder

Houston, TX

User avatar
jhoexp   100 mW

100 mW
Posts: 41
Joined: Jan 12 2017 10:08am
Location: Torino, Italy

Re: QS 138 70H with Gearbox

Post by jhoexp » Mar 07 2021 3:49am

j bjork wrote:
Mar 06 2021 5:50am
Then you can take the opportunity to photo and measure the gears :wink:
I havent seen any info about if it is spur or helical gears, or how wide they are.
Maybe I have seen tooth count somewhere, but I am not sure.
Hi, my first "real" post here... so I hope I'm off to a good start. :wink:
I have got this motor for a few weeks but started working on it just now.

Having seen how bad usually are these chinese manufacturer of cheap electric motors, this looks decent quality. Anyway they (QS Motors/SIA Ecosys) still looks amateurish at best in eveything else: datasheet, performance graphs, pr/marketing, etc....
Anyway in my case they removed the oil before shipping, mine has just a few ml left inside.

The gear reduction looks fine, it's 45/19 (2.36:1) helical gears. The output gear is almost 12mm thick.
The output shaft is 18mm on the inner side and 20mm on the outer. Bearings on the output shaft are 6203 and 6004 made by C&U. They look decent, but it's an easy upgrade if needed....
I have roughly checked hardness of the output gear, comparing to what I know, and it looks like 55/60 hrc.

The venting "thing" looks pretty well tought, even if they sealed just the inner perimeter and not the whole cover.
IMG_20210307_091354.jpg
IMG_20210307_091354.jpg (263.43 KiB) Viewed 1854 times
IMG_20210307_091420.jpg
IMG_20210307_091420.jpg (304.96 KiB) Viewed 1854 times
IMG_20210307_091450.jpg
IMG_20210307_091450.jpg (261.65 KiB) Viewed 1854 times
IMG_20210307_091526.jpg
IMG_20210307_091526.jpg (205.49 KiB) Viewed 1854 times
As you can probably see I had to face/modify/cut the motor mounts, because they are just useless (unless you have a pitbike, I understand).

This may be my first post but I have been lurking in the dark and following your posts, that were/are a very good source of inspiration! :thumb: Looking forward to see your build with the YZF, I am doing an Husqvarna TE 250, but given how lazy I am and all the latest valid excuses (work, covid, etc..) it will probably be done for the late summer.

I also agree with you about what you expressed in other posts, how poor the situation is now regarding controllers: we have motors but the few good escs are way to expensive/big and not really suited for the use we plan. Let's hope something changes soon.
Last edited by jhoexp on Mar 07 2021 11:48am, edited 1 time in total.

SlowCo   1 MW

1 MW
Posts: 1784
Joined: Jan 05 2015 5:43pm
Location: The Netherlands

Re: QS 138 70H with Gearbox

Post by SlowCo » Mar 07 2021 4:39am

jhoexp wrote:
Mar 07 2021 3:49am
I also agree with you about what you expressed in other posts, how poor the situation is now regarding controllers: we have motors but the few good escs are way to expensive/big and not really suited for the use we plan. Let's hope something changes soon.
Thanks for posting the photo's of the gear reduction :thumb:
It looks well designed and strong enough for most use cases. Regarding the controllers: what's wrong with the controller options they (QS Motors/SIA Ecosys) offer to go with this motor? The EM150-2SP or EM200SP seem to be more then capable of powering this motor.

User avatar
jhoexp   100 mW

100 mW
Posts: 41
Joined: Jan 12 2017 10:08am
Location: Torino, Italy

Re: QS 138 70H with Gearbox

Post by jhoexp » Mar 07 2021 5:24am

SlowCo wrote:
Mar 07 2021 4:39am
Regarding the controllers: what's wrong with the controller options they (QS Motors/SIA Ecosys) offer to go with this motor? The EM150-2SP or EM200SP seem to be more then capable of powering this motor.
They are low voltage (72V) basic escs. They are sure good enough for now, but already serioulsy hindering max motor power, rpm and overall efficiency. A much higher voltage controller will open new levels of performance at higher efficiency, positively affecting the whole bike use, not only power but also weight, efficiency, fast charging, etc... It makes no sense pulling 400A at 72V @low rpm, when you can have the same power with a much broader rpm range and way less heat pulling 200A @144V or even better 100A @288V.
Alta, KTM, etc... they all have chosen much more higher voltage system with smaller motors and gear reduction.

This low voltage system are ok and safer for DIY, but acceptable just now that electric bikes are a novelty and the whole market is still in it's infancy. We need high voltage to have all the power and efficiency of oem bikes.

j bjork   100 kW

100 kW
Posts: 1069
Joined: Aug 31 2018 3:01pm
Location: Linköping, Sweden

Re: QS 138 70H with Gearbox

Post by j bjork » Mar 07 2021 8:05am

First time I have seen how the gear reduction looks, thanks :thumb:

It is nice that they put a support bearing on the outside of the motor axle.
It will be interesting to see how it holds up when someone starts to push it.

I think the BESC G4 would be really interesting to try on these motors.
700 phase amps, and was it max 130V?

john61ct   100 GW

100 GW
Posts: 7832
Joined: Dec 18 2018 2:06pm

Re: QS 138 70H with Gearbox

Post by john61ct » Mar 07 2021 8:55am


jhoexp wrote:As you can probably see I had to face/modify/cut the motor mounts, because they are just useless (unless you have a pitbike, I understand).
I had never heard of that term.

From wiki:
Now the most common style of pit bike (and specifically marketed as Pit Bikes, opposed to introductory Motocross models) A broad look these machines are based on the Honda CRF50 and feature the perimeter frame chassis. New versions feature a CRF 50 motor mounts and may have a displacement between 50-190 CC. The typical wheel size is a 14" front and 12" rear wheel. These models were less expensive (up to 60% less than Honda and Yamaha manufacturers) and use parts compatible with the established aftermarket industry
Rather than messing with custom mounts, would it make sense to buy a suitable frame that already fits the motor

as a starting point for a custom build?


HrKlev   100 W

100 W
Posts: 295
Joined: Dec 06 2019 10:24am

Re: QS 138 70H with Gearbox

Post by HrKlev » Mar 07 2021 9:30am

Thanks for posting the pictures, Jhoexp!

I am curious if the output shaft is the same size as the non-geared qs 138 motor? Have you checked yet?
Hubdrive as middrive, with torque sensing EMTB build: viewtopic.php?f=6&t=107622

6x6 conversion: viewtopic.php?f=34&t=109567

User avatar
jhoexp   100 mW

100 mW
Posts: 41
Joined: Jan 12 2017 10:08am
Location: Torino, Italy

Re: QS 138 70H with Gearbox

Post by jhoexp » Mar 07 2021 11:26am

j bjork wrote:
Mar 07 2021 8:05am
It will be interesting to see how it holds up when someone starts to push it.
I'll try my best :D , but I doubt I will have it ready soon...
I think the BESC G4 would be really interesting to try on these motors.
700 phase amps, and was it max 130V?
Yes, and there is also the HESC from Hackey, and the Power velocity 24fets, all VESC derived. But none is really available yet...
Then there is the Kelly KLS-8080 that have 144V versions. Not really cheap and can't really find even one single use case. :(
I'd like to try, but 800-1000 euros for a jump in the dark... :confused:
Last edited by jhoexp on Mar 09 2021 4:08pm, edited 1 time in total.

User avatar
jhoexp   100 mW

100 mW
Posts: 41
Joined: Jan 12 2017 10:08am
Location: Torino, Italy

Re: QS 138 70H with Gearbox

Post by jhoexp » Mar 07 2021 11:28am

HrKlev wrote:
Mar 07 2021 9:30am
Thanks for posting the pictures, Jhoexp!

I am curious if the output shaft is the same size as the non-geared qs 138 motor? Have you checked yet?
No, unfortunatly it is not. It's a 17mm shaft, the same that pit bikes usually have. I haven't been able to find 520 pinions, in fact I bought a 428 with a new chain and rear sprocket. I hope it holds...

Edit: I maybe wrong, not sure what the non-geared QS 138 has, but the one I have seen was keyed and intended to be used with a belt pulley.
Last edited by jhoexp on Mar 09 2021 4:09pm, edited 6 times in total.

User avatar
jhoexp   100 mW

100 mW
Posts: 41
Joined: Jan 12 2017 10:08am
Location: Torino, Italy

Re: QS 138 70H with Gearbox

Post by jhoexp » Mar 07 2021 11:38am

john61ct wrote:
Mar 07 2021 8:55am
I had never heard of that term.
They are pretty common here in Italy, they were originally intended to move around in the pit areas, but now some even race them on mx or kart track as minimotard.
Rather than messing with custom mounts, would it make sense to buy a suitable frame that already fits the motor
as a starting point for a custom build?
Sure, but you will be stuck with a pit bike: it's fun, but really small and useless outside the track.
I want a full size dirt bike and that motor should be capable of powering one. The original QS138 (with no reduction built in) had much friendly motor mounts. I had already designed my whole build around that, but making a good jackshaft is no simple thing... so when this came out I knew I had to make some modifications.

Jordan325ic   1 W

1 W
Posts: 58
Joined: Aug 05 2020 6:44am

Re: QS 138 70H with Gearbox

Post by Jordan325ic » Mar 08 2021 9:15am

jhoexp wrote:
Mar 07 2021 3:49am
The gear reduction looks fine, it's 45/19 (2.36:1) helical gears. The output gear is almost 12mm thick.
The output shaft is 18mm on the inner side and 20mm on the outer. Bearings on the output shaft are 6203 and 6004 made by C&U. They look decent, but it's an easy upgrade if needed....
Just curious, where are you measuring the output shaft dimensions? My output shaft matches the pdf, 17mm/14mm
Edit: Nevermind! I missed that you mentioned this a few posts up.
qs138-output-shaft.jpg
qs138-output-shaft.jpg (34.32 KiB) Viewed 1759 times
QSMOTOR Z138-03 Mid Drive Motor with gearbox.pdf
(550.78 KiB) Downloaded 52 times
Last edited by Jordan325ic on Mar 08 2021 9:38am, edited 1 time in total.

Jordan325ic   1 W

1 W
Posts: 58
Joined: Aug 05 2020 6:44am

Re: QS 138 70H with Gearbox

Post by Jordan325ic » Mar 08 2021 9:37am

qs138-with-gearbox-photo-labeled.jpg
qs138-with-gearbox-photo-labeled.jpg (127.56 KiB) Viewed 1743 times
So as I understand it the correct orientation is:
#1 - vent, ideally facing downward.
#2 - Drain plug, ideally the lowest point of the fluid housing.
#3 - Fill plug.

I wonder how sensitive the unit is to other mounting orientations, besides the increased difficulty in draining and re-filling the unit...

Post Reply