Replace axle in Go SwissDrive rear hub drive motor?

bombadero

Member
So I recently broke the axle on a Go SwissDrive rear hub motor for my HP Velotechnik Scorpion. I've opted to purchase a replacement wheel at retail cost, which the distributor has kindly offered. That leaves me with a perfectly good, brand new hub motor that is useless owing to a single part, the axle. It's my understanding that it is somewhat technically challenging to replace the axle in a hub motor, but it can be done, assuming I can obtain the axle part. Does anyone have any experience doing this, on any hub motor system, or specifically Go SwissDrive? Seems a shame to waste a perfectly good motor. I can do it through HPV but it would cost $750. Of course that's half the full price, so still kind of a deal given that I got the wheel for free, but spending, say, $100 would be even better.
 

Attachments

JRA

Well-Known Member
That's a big bummer bombarder! Seems so unlikely that you could put enough torque to do that but obviously you don't know your own strength or GSM does't add enough heat treatment to their axles...... It does help to do a bit on each side with any nutted type axle at a time though while keeping an eye on alignment of the wheel in the chain stays.

Looked for an exploded view of the GSM and only found this video:
that shows all the parts and pieces in their proper order:

Screen Shot 2019-06-17 at 2.31.44 PM.png

It doesn't look to me to be too hard to get to the axle and replace it if you can source one? Of course you will have to unlace the rim to get the motor apart as we discussed in your other thread. Certainly makes sense to at least try.
 

bombadero

Member
@JRA thanks for the vid. Yeah, I contacted GSD to see if they can source me an axle directly. If not... I guess I would have to buy a used motor as cheaply as possible on eBay or something and cannabalize it.

It did seem strange to me it would shear, but since it's via HPV, I have to go through their service department and they seem to think it's my fault, so these are my only options.
 

Ravi Kempaiah

Well-Known Member
@JRA thanks for the vid. Yeah, I contacted GSD to see if they can source me an axle directly. If not... I guess I would have to buy a used motor as cheaply as possible on eBay or something and cannabalize it.

It did seem strange to me it would shear, but since it's via HPV, I have to go through their service department and they seem to think it's my fault, so these are my only options.
Take that broken axle to a CNC machinist and he could produce something similar.
As JRA stated, it's hard to know what kind of heat treatment they did but you could get very strong steel rod or an axle from other motors like Crystalyte, MXUS and machine it to GSD size.
Any skilled CNC guy could do that for $100.
 

rich c

Well-Known Member
Take that broken axle to a CNC machinist and he could produce something similar.
As JRA stated, it's hard to know what kind of heat treatment they did but you could get very strong steel rod or an axle from other motors like Crystalyte, MXUS and machine it to GSD size.
Any skilled CNC guy could do that for $100.
I think you are substantially underestimating the cost of a custom part Ravi. Around here, you won't get the CAD work done for the programming for that, let alone the machining and heat treat for a street walk-in single part. I had a water jet cut part quoted once, they quoted $150 for the CAD and programming. Programming is easier now, but prices hardly ever go down in machine shops.
 

Ravi Kempaiah

Well-Known Member
I think you are substantially underestimating the cost of a custom part Ravi. Around here, you won't get the CAD work done for the programming for that, let alone the machining and heat treat for a street walk-in single part. I had a water jet cut part quoted once, they quoted $150 for the CAD and programming. Programming is easier now, but prices hardly ever go down in machine shops.
I think you're right.
I believe it could be done for <$250. I have read amazing custom part stories on endless spheres. Custom chainring for high-powered motors, swingarms etc.
 

bombadero

Member
So it looks like I will have to have a custom part milled. I reached out to GSD, and this was the somewhat humorous response:

Hello,



it is not possible the axle to buy separate and the repair to do by self.



Freundliche Grüße / Best regards
Well, yes, I can do it by myself, but only if GSD will sell me the axle, and apparently they will not - so machining will be the only option. I've been told the Endless Sphere forum is a good place to hunt around for this sort of thing.
 

JRA

Well-Known Member
Well at least next time it fails you will have all the spare parts you need except for the axle.....
 
The yoda meme wins you the best attitude of the day award.

I've considered buying a SwissDrive system, as I understand it has the torque sensor and controller built into the motor like BionX. Does anyone know if it also uses canbus?

Surprising to break an axle, did it happen on a ride or while tightening it or something else?
 

bombadero

Member
@Scott Adams yes, I was tightening the nut on the drive side. My mechanic's theory was that because I had not tightened the non-drive side first, which has the torque arm, there was enough wiggle while I was tightening it to introduce some extra torsion and shear the axle bolt under the 40-45 Nm required by the manual. It seems strange to me, but there is no real way for me to argue the point with HPV. My options were ~$1,000/1 week for a new motor at the dealer's price or ~$750/7 weeks to ship it round trip to and from Germany for repair. I opted for a new wheel, which leaves me with this extra, brand-new, broken wheel. If I can get a replacement part for the axle somehow, it should be much cheaper than $750 and would give me a spare motor, although I do have to get it built back into a wheel for probably another $200. But all in, I'm hoping to repair it and rebuild the wheel around it for ~$400.

My understanding is that the newer ones are canbus; mine is the older model that uses bikebus, since the newer reason is not compatible with my old (2006) Scorpion for a reason I can't remember. My understanding is also that the bikebus motors are more reliable than the newer canbus ones. You can buy the bikebus motors for about $650-750 plus shipping from Germany on eBay. Still not cost effective for what I'm trying to do here, but reasonable for someone looking to buy one new.
 
Shame to go through so much hassle - do have any comments about the performance of your SwissDrive when it was working? There aren't very many reviews.

I've opened a BionX motor, but have not put it back together or laced it into a wheel.

The BionX required some work to pull the two clamshell halves apart using a 3 jaw puller. From the video above, I wonder if the SwissDrive is easier to separate as it may simply use screws to hold the outer housing halves together?

The BionX axle also has a flat surface cut into it near where it meets the housing, this is where the torque sensor is fitted. This might need to be machined for you if yours is similar.
 

bombadero

Member
Again, this is a brand-new motor, nothing wrong with it except that I broke the axle accidentally. It's actually a warranty replacement for a motor that did fail, due to a failed torque sensor. I'm getting a third motor at my own expense to get the trike running again, but have an otherwise perfectly good motor now (motor 2) that is essentially a very expensive and very heavy paperweight now. I could have that motor repaired for about $750 by round-tripping it to HPV in Germany and back, but I think I can do so for much cheaper.

Motor 1 may have failed due to a number of causes - moisture getting in through the disc rotor screw holes because the mechanic didn't inform me I needed to plug them; or a bent axle, which itself could have been caused by a couple of things. The point is, motor 1 could have failed on its own, but it's unlikely. Motor 2 has not failed at all, the axle simply sheared when I was attempting to install it.

Generally, Motor 1 performed great. The GSD system is very quiet, almost silent. I really like the Bosch system we have on another bike, an R&M - it's insanely tough and reliable. However, the one complaint I have about the Bosch system is that it is very loud compared to other brands. The GSD system is also very torquey - I get faster acceleration out of it than the Bosch system, although that's generally true when comparing mid-drive and hub-drive systems from what I understand. Hub motors give better acceleration, but mid-drives are more efficient.

The bikebus version that I have is supposed to be very reliable. The newer canbus version, from what I have heard, has some firmware issues causing motors to brick from time to time. My mechanic has said that he's had a lot of warranty replacements of the canbus version. I'm replacing my current motor with the same one because that's the system already on the trike and I don't want to rebuild the whole thing with new batteries, a new computer, et cetera. Actually I might be able to salvage the batteries and reuse them, but I would definitely need to replace the motor and computer, at a minimum. If motor 3, once it arrives and is installed, itself fails some day, then I will probably rebuild the trike with something like an EBO kit, especially as I will be out of warranty at that point.

As far as a brand new build, I honestly wouldn't recommend it simply because GSD is being liquidated at of the end of this year. According to EU regulations, they are required to supply spare parts and service for the next 5 years beyond that, but as you can see from the email I posted above, they don't have the best service demeanor for an English-speaking DIY customer in the US. They essentially told me, "No soup for you!" They mostly do B2B, not B2C, like a lot of manufacturers. In my case, service is through HPV, not directly through GSD. I only reached out to GSD to see if they would be willing to sell me an axle directly. It seems to be a good system on par with Bosch drives, but a product is only as good as either the service of the manufacturer or your own ability to service it. I'm not aware of a big DIY community around this particular drive, as it is primarily sold B2B in big contracts with e-bike manufacturers and bike-share fleets. If you are looking for a good hub-drive system I would look at EBO or Luna Cycle as two of the most reliable. A lot of people like Bafang, but I've heard their motors burn out from time to time. EBO and Luna Cycle use Chinese systems as well (Luna Cycle even sells Bafang systems), but they themselves are based in the US so you're more likely to get good service. They will also build the motor directly into the wheel of your choice. I'm probably going to get a Luna Cycle Golden Pie v5 system myself when I convert an old 1990's stump jumper I have to an e-bike later this year. If I have to rebuild the trike in the future I'm looking at the EBO Clydesdale system. HTH
 
Thanks for posting your story, you have excellent insights.

I've converted two Stumpjumpers and both are great ebikes with BionX drives.

https://electricbikereview.com/forum/threads/light-touring-build-using-bionx-drive-without-a-bionx-battery.28234/#post-200319

I like having a motor with built in controller, torque sensor and communications to play with as a DIY guy. Might try replacing the control console with an arduino sometime on my I2C system.

It's a shame both SwissDrive and BionX have left the playing field.
 

bombadero

Member
@Scott Adams yeah, it frankly sucks. In the case of GSD, it seems especially disappointing because apparently they were profitable, just not as much as they would have liked, as I understand it (could be wrong). It's bad enough when a good product or company dies because the company has no choice, but it's especially irksome when it's simply because the parent company is lazy or greedy. In a market where growth in e-bike sales is explosive, particularly in Europe, they could certainly have made GSD more profitable if they wanted to.

BTW, regarding GSD, I just found out from HPV that the service obligation for GSD is 2 years, not 5. So that's even less of a reason to recommend them even though they did generally make a good drive system. The EBO and Golden Motors kits are actually really good - although they unfortunately don't have torque sensors.
 

bombadero

Member
So the new motor (motor 3) should be in the mail soon. I ordered an AC Delco torque adapter and it arrived today. I threw the male end in a vice and inserted my Tekton torque wrench in the female end set to 40 Nm, and lo and behold, at 40-45 Nm, it doesn't click, so it appears to be mis-calibrated at the moment. I also ordered an AC Delco digital torque wrench, so I guess that's what I will be using on motor 3. It appears Tekton's QC department cost me $929. I mean, wrenches go out of calibration, but I've only owned it for a few years and it isn't like I'm a professional mechanic or contractor using it hundreds of hours a year.
 

bombadero

Member
While I wait for motor 3 to arrive, I unlaced the wheel around motor 2 and removed it's screws. Unfortunately, while there is hypothetically nothing holding the wheel together other than the decal you can see in the attached photo, the two halves of the motor casing seem to be practically glued together. I'm not sure what I'll need to do to get them apart to get at the axle. I've seen a few videos on YouTube of people with GSD motors taken apart, all in German, but none of them go through the process of actually taking one apart. I also posted on Endless Sphere about fabricating an axle for it, but so far I haven't gotten a single response. I guess I'll comment on one of the videos and see if they get back to me.
 

Attachments

bombadero

Member
Hm, the mechanic at our LBS (LeBS? LEBS? eLBS?), The New Wheel mentioned that possibility as well, although he has also never worked on this motor. They don't sell HPV, they're the ones who sold us our R&M. The guy who retrofitted our HPV Scorpion doesn't work on motors either, as they are always shipped back to HPV for all service needs. This looks like it may do the trick. I also left a comment on a video on that German guy's channel, hopefully he speaks English and gets back to me. This is the video:


However, he has different models and scrubbing around the video I don't see a gear puller among his tools.
 

bombadero

Member
Different motor design, but this guy shows how to take apart a hub motor with a gear puller, and has some good tips as well:


Looks like I need to invest in another tool (it's cliche, I love buying tools :p).