Water inside Hub - how to clean

[freddofrog]

I've had this Cyclotricity kit for over 4 years now. It's a 250W front-wheel 700c kit.

Cable entry was straight down the forks - from reading a few threads on this forum I was aware that this was not a good way for the cable entry due to rain, but I hardly ever used the bike in the rain - only used for short runs to shops and occasional 20 mile runs in sunshine (very light rain on a few occasions when going to shops).

Then about 6 months ago one of my sons started to use it daily to commute to work and back (2 miles each way). He was using it in very heavy rain, but Id forgotten about the potential problem of the cable entry from the top.

Eventually he said that it started to become "jerky". I checked the wiring, then took the wheel out, and saw water drain out where the wiring enters the crank. After drying it out , I taped it up very well and he carried on using it but after a week or two it no longer reached top speed. I checked it all again, and felt that the wheel didn't seem to run freely. So I decided to take the motor/gearing out of the hub.

The motor is an MXUS XF07 - I did a search and found a couple of Youtubes on how to undo that and similar hubs - I ended up buying this useful tool to get it undone https://www.amazon.co.uk/FreeTec-Variable-Spanner-Wrench-Adjustable/dp/B07C7SSS3S/ - worked well with my son as assistant .

Here are two pics of what I found inside !!!

Assuming that the nylon gears and motor are not ruined, the questions are
1. What should I use to clean it all up before I strip it down
2. What should I use to clean the parts once it is stripped down
3. What should I use when I reassemble it

 

[Kwozzymodo]

That looks gnarly! Before you clean it up properly, it might be worth trying to check the state of the windings and connections in the motor itself. You can probably wipe away most of the congealed grease with some kitchen towel before taking the rest of it apart.

The windings etc., need to be fully dried out. You can use contact spray for the contacts in the motor/sensors, etc.

If you get as far as reassembly, you can probably use a degreaser to remove all the crud. A dab of grease on the gears helps longevity.

Might be worth testing before it all goes back together.

 

[Nealh]

The windings etc, etc will all be as bad except the copper will be oxidised Green and if it is sensored the halls will likely need replacing, get it apart and see how bad the windings are first.
A brush , Meths or Isopropanol bath would be an option then a thorough rinsing or two and then a thorough drying out period, most should evaporate in a dry warm ventilated space.
Once clean have a good look at the nylon gears to see if they are badly worn.
Greasing the mech side any grease that is non petroleum based so lithium/silicone based and a very big dollop of it.
Leccy side when clean a good spray of ACF 50 and wipe off excess.
Once done it isn't a given it will be happy working but stands a chance.

 

[freddofrog]

Thanks for the useful guidance guys. For some reason I'm a bit hesitant to strip it down, probably because it looks more like taking a clock to bits

I'll update with before-and-after pics when I've stripped it down.

btw I found a thread on this forum from 2014 showing what the MXUS should look like inside https://www.pedelecs.co.uk/forum/threads/inside-the-mxus.17897/ (as I say, I got mine open with an off-the-shelf 2-pin pin wrench from Amazon)

 

[Nealh]

You have nothing to loose by stripping it down because as it is, it is next t useless. If it goes pear shaped then new hubs are quite cheap to buy.

 

[freddofrog]

I hadn't thought of buying a new hub on its own.

Just had a look on ebay and quickly found MXUS for £74.80 which is actually same XF07 e.g. https://www.ebay.co.uk/itm/MXUS-36V-250W-350W-Front-Rear-Ebike-Hub-Motor-Wheel-Freewheel-Cassette-48V-500W/223797259546

Makes the thought of stripping it down less of an issue - as you say, nothing to lose.
Many many thanks

 

[gw8izr]

I hadn't thought of buying a new hub on its own.

Just had a look on ebay and quickly found MXUS for £74.80 which is actually same XF07 e.g. https://www.ebay.co.uk/itm/MXUS-36V-250W-350W-Front-Rear-Ebike-Hub-Motor-Wheel-Freewheel-Cassette-48V-500W/223797259546

Makes the thought of stripping it down less of an issue - as you say, nothing to lose.
Many many thanks

Do you know anyone local with an ultrasonic cleaner? I’d have that in my ultrasonic bath for an hour or two and see how it tests afterwards.

 

[Nealh]

With an exact replacement motor you don't need to rebuild the rim, all you would do is swap over the internals in to the cleaned existing hub. On that hub you would have to factor in duties/vat & handling fees so about £25 on top of the price.

 

[freddofrog]

Back for an update and more questions - I only found the time to start to take it apart yesterday (Saturday)

Do you know anyone local with an ultrasonic cleaner? I’d have that in my ultrasonic bath for an hour or two and see how it tests afterwards.

If possible, I'd have it in your ultrasonic bath too LOL

With an exact replacement motor you don't need to rebuild the rim, all you would do is swap over the internals in to the cleaned existing hub. On that hub you would have to factor in duties/vat & handling fees so about £25 on top of the price.

Other than looking on alibaba for a Chinese supplier (MXUS doesn't sell direct) do you know of any reliable Chinese suppliers ?


I've taken the planetary gears and sun gear off.
Had to use a gear puller to get the planetary off (fortunately the one I have ranges from 15cm down to 5cm), then an impact driver to get the screws out of the sun gear.
Photos below show what's remaining to get to the stator windings.

front

back

How do I get the front off ? Does it just pull off with a gear puller ?

 

[freddofrog]

How do I get the front off ? Does it just pull off with a gear puller ?

Answer is, yes the front does pull off. I used the same gear puller, and it came away very easily.

But the back (I hadn't realised that that is the rotor) was very difficult to pull off (used the same gear puller). While the rotor was slowly (and judderingly) coming away, I thought it was the wrong thing to do, but carried on until it came off. What a mess, the magnets in the rotor are all rusty, and the bearing in the rotor is seized. The laminations on the stator don't look very happy either. In comparison, the stator windings and the hall sensors don't look so bad actually.

So the main problem seems to be that the clearances between the stator and rotor are badly affected by rust, and the rotor bearing is more-or-less seized. It's that bearing which was giving the bad "feel" to the wheel rotation (when rotated by hand in my initial assessment).

I hadn't realised how this thing works - the stator is locked to the axle, the rotor carries the sun gear, and this rotates inside the planetary gears, which mesh with the ring in the hub, causing the hub to rotate at lower speed than the rotor. Nice.

I'll take more pictures, and post them in this thread. After that, I might either 1. create a new thread showing how the MXUS XF07 comes apart or 2. create a youtube video and put a link to that. My preference is the latter tbh.

In the meantime, I'm thinking that it's going to be easier to do what @Nealh suggested in #8, because the rotor is a mess. This goes as a warning not to get water inside any electric motor, and if you do, strip it down immediately.