RUST: DIY Hub Motor Repair & Restoration

[Kingfish]

Pictures to date:

Front Hub after cleaning. This was absolutely bright and spiffy after the acid bath, however it oxidized during the drying cycle. Still - the patina is very thin and I might just run with it; these items continue rust right in front of you and I've never seen anything like it! Note that I can now read the HE part numbers!

Another view of the same stator. I suppose if I dunked it into a gallon of Isopropyl alcohol after the acid wash/water rinse - and then stick it in the oven - well, that would make a nice explosion I suppose... but it would be dry! Hmmm, scratch that idea :lol:

BEFORE shot of the same hub for reference.

Here's the Rear Hub stator again. Presently I have it soaking in the acid wash, but this shot was taken right before that. Notice the green oxidation on the windings...

...right next to the axle at the top.

Harder to see it in this photo, though in real life, it shows up better. Just wait till I get this one cleaned too!

Closeup of the corrosion. Why is it that these hubs do not come with any sort of varnish coating again? I'm confused. :x

The Rear rotor cleaned up OK; I am not entirely happy about that but it's the best that I could do. I used the heat gun to drive off the moisture.

Closeup of the same rotor. Lovely little rusty pits all nicely dug out of the cheap magnet plating.

BEFORE shot for reference. Well, considering where it started a lot of rust was removed.

As I said, the Rear hub stator is now soaking in the acid wash of 5% vinegar, and it's doing a bangup job at it! Doesn't hurt my hands either, though it's kinda smelly and dank in that room like, like... like a rusty nail! :lol:

Onward through the thrill of fixing someone else's manufacturing problem.
~KF

 

[dnmun]

that's why the auto body repairmen use metal prep. the phosphoric acid dissolves the rust and leaves a coating of iron phosphate which does not rust any more, so they can paint over it without fear that the rust will come back.

 

[Kingfish]

that's why the auto body repairmen use metal prep. the phosphoric acid dissolves the rust and leaves a coating of iron phosphate which does not rust any more, so they can paint over it without fear that the rust will come back.

You are most wise. Now I understands!

The Rear Hub stator came out better than the front - although I was a bit tired to post the pictures and wanted to get on with my dinner. Pictures will get posted this evening. Nothing has been coated yet. There's a body shop supply 1/4 mile away so I will trip down there maybe at lunch break or before catching the bus to see if they have the phosphoric acid stuff.

Dennis, is there a trade name I should be looking for?

Link to intersting article on phosphoric acid-based metal prep.

Gosh I'm dumb!
~KF

 

[dnmun]

nope, it has been decades since i used it on my old citroen which is when i discovered it by accident. that was a neat article you googled up, maybe it is cheaper at home depot or lowes. don't know how it will affect the copper though, that is the unknown too. not a good sign that the vinegar discolored the windings in the hub you worked on. or how the magnets will respond either. BOL. dm

 

[Harold in CR]

Y'all talking about "Extend" metal prep ?? It turns the rust to black iron oxide ?? Hope I got that last part right.

Painted the whole log hauling trailer I built, and, it was out in all the bad Florida weather, for several years. never a spot of rust showed up.

 

[Kingfish]

Dennis: Vinegar did not discolor windings: It cleaned them right up spiffy bright!
Harold: Good to know of another trade name!

I did a bit of searching and found this stuff at HomeDepot.com: Miracle Sealants 32 oz. Fast-Acting Phosphoric Acid Cleaner

Somewhere I read that it was 23% acid.

I took my lunch break and stopped at the body shop supply ¼ mile from my current work site. They had this stuff: Sem Products 69508 Rust-Mort.

Reading the label, the acid is 75%, and you paint it on in thin coats. The price was $23 for the 16 oz. bottle, small paint brush, and plastic cup: Less than if I ordered it all on Amazon, plus – I don’t have to wait for delivery and I don’t have to walk 1.5 miles to the nearest Home Depot for something they might not have.

My plan will be to apply it on the magnets and the teeth facing the magnets tonight, and to avoid contact if possible with any other non-iron surfaces since they are already clean enough.

Thanks for the insights guys! Much appreciated
~KF

 

[dnmun]

i remember it was strong, and expensive too.

life is hard when your horse is laid up lame. you need another bike.

wear glasses for sure, and old clothes, hehe. hope you don't get evicted if it stinks up the place.

 

[Kingfish]

Apologies for taking so long to post: I have been suffering from the dreaded lurgy since Monday afternoon and it has zapped my energy and ambition to do much more than drag myself to work.

I am still waiting on the seals to arrive; near as I can tell the local “supplier” doesn’t have them in stock, and so we are in this waiting loop. I should have picked another source, cos after 11 days and still no-fulfillment does not bode well. :| It’s shaping up that I won’t have this repaired until after the holidaze.

That said, here’s the last of the pictures from Monday night cleaning.

I went down a different route on the rear hub: It soaked a lot longer in the vinegar, and I used a plastic scrubby on the exterior on top of the toothbrush. Some of the plastic bits from the scrubby appear in the close-up shots. Instead of hot-water rinse (as I did with the front) I used cold water: This arrested rusting action before the oven-drying treatment. Also, I used the heat gun to drive off the excess moisture before placing the stator in the oven. Overall the development of new rust was reduced somewhat when compared to the front stator.

This image was taken after the final acid wash, and immediately before rinsing in cold water: Nice and bright with nearly all the residue removed.

BEFORE...

AFTER: Close-up of the Hall Effect sensors: You can read the part numbers now! Blue thread-like items are from the plastic kitchen scrubby.

This is after oven-drying: A patina of rust still forms, though not as severe as the front stator.

The whole view. Some crusty parts remain; I shall never get to it all. And yet, it should have never happened! :x

I have not noticed any additional rusting since Monday; the stators are in a dryish room indoors where the humidity is relatively low. I hope to complete the next phase this afternoon or tomorrow if I feel better. I am convinced the only reason I have the lurgy is cos I haven’t been riding my fun ebike and getting fresh air instead of being spooned in on the bus communing with all sorts. (No offense: Bus people though are very nice and interesting.) 8)

<cough>
Reaching for the Kleenex...
<sneeze!>, KF
yuck!

 

[ohzee]

Damn that is quite the improvement Kingfish I am impressed. glad you were able to get her cleaned up.
Wondering what the improvements will be like for you. Thanks for the update.

 

[dnmun]

wow, that is clean. i did see the phosphoric acid cleaner at the home depot yesterday by accident. it is $15/gallon there.

you really did get it cleaner than i would have expected. once the water is inside the hub it just keeps all the magnets and the stator poles wet so i am surprised the hall sensors did not short out too with that much water in there.

 

[bigmoose]

If you are not going to paint it after the water rinse; spray it with WD-40.. Water Displacing formula 40... :wink: that should help to keep the oxidation down. Then if you want to spray it with insulating varnish, dunk it in your solvent of choice to get the WD-40 off after everything is dry of water.

 

[Kingfish]

Status

The last of my parts arrived over the holidays. I’ll write more about that later. For now, I just want to touch upon the work required to complete the project:

• All parts have arrived. (Done)
• Treat stators and rotors with Rust-Mort and remove the iron rust prior to varnish treatment. (Started)
• Hub covers need cleaning and prep work before sending off to the machinist to replace the bearings and cut drainage/venting holes along the periphery.
• Upgrade phase wiring on Rear Hub
• Varnish-coat the stators and rotors.
• Reassemble and test.

Rust-Mort treatment
I think it was wise to pretreat the rusted parts with vinegar prior to applying Rust-Mort because this removed over 90% of the nasty debris. Today I dispensed out about ½ ounce of the Rust-Mort into a hard-plastic cup. The liquid was viscous and had a faint green tint to it. I used a 1-inch wide horse-hair paint brush and gently applied the thinnest of coats, being very careful not to have a drippy brush, and taking my time so as not to create splatter of any sort.

Both stators were coated once and allowed to dry. It’s too cold to do this outside and instead had the exhaust fan going in the bathroom to pull the acrid fumes away. The fumes were greatly less than during the vinegar treatment, though it still smells like a dank rusty bucket of nails in that room. As I applied each brush stroke, the orangey rust patina turned first to pale lavender before developing into a gunmetal blue-gray color, similar to dull pewter; it was changing right before mine eyes. There was very little residue left as I made sure the brush was never soaked or drippy. Here’s before and after…

Front Hub after vinegar treatment.

Front Hub after one thin coat of Rust-Mort. The directions say to apply 3-4 thin layers, allowing each coat to dry before applying the next. Notice the bubbling-residue: This is very frail scale that when dry can be removed using a toothbrush with light effort.

Everything that is iron-base turns into this flat-gray color; anything that is rusty is consumed – if the brush gets to it. I painted up the entire stator and axle; any part that developed iron rust.

This is the Rear Hub after the vinegar treatment. Notice the crusty residue where the axle joins with the stator.

Rear Hub after one thin coat of Rust-Mort. Quite a difference, and we’re not done yet! Notice the fine dusting of iron-phosphate precipitate on the axle.

And wallah; here we are as a pair. These surfaces remained “wet” for about 3 hours as the coating slowly dried.

Anyway – I just wanted to provide some status on how this was going. I will add more treatments during the week. In the meantime the covers need prepping and scheduled with the machinist.

Feeling like a little plating shop, KF

 

[neptronix]

Freaking amazing.. i can't wait to see if... these actually run

Keep up the good info.

 

[biohazardman]

Wow, what allot of werq you did there. I can't believe those were so bad. I opened up my BMC V2 after 2K+ of riding, much of it in the Portland rain, and it was shiny and new looking inside. Only goes to show how individual these things really are they are hand made after all. I hope they run good when you are done.

 

[Kingfish]

Biohazardman, that’s a spiffy-clean motor there!

My first hub motors were 9C from EBikes.ca; I have not removed the covers to inspect them because they have performed well even though I’ve gone through two Seattle winters. The problem hubs are the ones I purchased from E-BikeKit last May. However I can tell you that the construction and design is identical in mostly all repects.

<soapbox: ON>

It’s been said on a related thread that bringing the bike (hubs) inside will reduce/inhibit the problem, and that's completely flawed thinking. My behavior has not changed: I ride in sun or rain, and I store the bike outside under cover, or inside where it is dry. When the motor is running, the internal air becomes warm, the pressure increases, and the exchange of the atmosphere is outward through whatever porous interface (unless completely sealed – which I suspect is not possible given the axle). When I come to a complete stop, when I am sitting at a stoplight, the motor will begin to cool, the internal pressure reduces, and the transfer of air (however humid) reverses. If it is chucking down rain, and if liquid is in contact around the axle or any other leading edge, it will be drawn inside – there is no stopping it.

It is a flawed design. The covers should be vented all the time to prevent the pressure differential altogether, just like a starter motor or alternator: open to the atmosphere. If the motor was ventilated along the periphery of the covers then any moisture accumulating will eventually be released through centrifugal force. If the rotor and stator are treated and sealed (like any normal motor) then rust will not form.

It is just plain crappy manufacturing, and products like this should not be allowed into any civilized country. We have a perfect case to raise a consumer class action suit against these types of imports. We as consumers must demand quality product! And if we can’t get support and replacement from our suppliers, then we must vote with our feet, our wallets, and create our own opportunity!

Suppliers must be held accountable, must warrantee against rust and corrosion, must guarantee that phase wires will not melt the insulation when operated at rated capacity, and ensure that the Hall Effect sensors do not pop off. In my mind, a warrantee should last 3 to 5 years.

Think about it: When you purchase an automobile, wouldn’t you expect the vehicle to last at the very least 3 to 5 years in rain?

So I ask again: Why are we taking it up the arse on this?

To be clear: I greatly appreciate the efforts of our present suppliers to provide opportunities for us to explore this wonderful hobby...
However - I will not buy another Chinese hub motor: I am going to make my own!

If I can just need to finish this project first...
<soapbox: OFF>

Motivated, KF

 

[newb]

heya KF,

if u haven't watched justin's newest VEVA presentation i recommend u do, very informative. among the things discussed is water intrusion issues w/ hub motors including pressure differences.

posted here: http://endless-sphere.com/forums/viewtopic.php?f=30&t=34972&p=510532&hilit=justin#p510532

[youtube]gwlbAJLzI_w[/youtube]

 

[neptronix]

Well said, KF.. maybe this will steer you in the direction of a mid-drive, where the motor is not having water kicked into it, and can be reasonably shielded.

Maybe your coating will work just peachy though.. and people in rainy / snowy climates will take up the cause, en masse.

 

[Harold in CR]

I think Y'all will find, that, As the motor gets hot, no matter from use, Sun shining directly on it, VERY hot temps of the day, the heat will create pressure and push out the extra air created. THEN, if you go out in rain, through sprinklers working, or any other moisture effects, that will cool off the air under pressure, inside the motor, then, you create a small vacuum effect, and suck moisture through the seal.

When we had the Manufacturing business, we also sold and somewhat serviced Metal Detectors. Especially problematic was, underwater detectors. They would be left laying on the work deck of the Boat, while the Blower was used to move sand off the bottom of the ocean. After 20 minutes of blowing, divers would go in the cooler water with those very warm detectors. Instant vacuum sucked salt water into the cases. We even had one brought to the shop FULL of salt water. They didn't even open the case and dump out the salty water.

We were pretty well known to be the go to place for detector repairs.

This was finally proven, by putting a plastic garbage can on deck, half filled with fresh water. Detector comes up, put it in the can. Take it out when you go in the water. stopped nearly all the seepage problems.

 

[biohazardman]

Yup it is very clean alright. After finally watching Justin's video I found that there are many reasons my motor is dry and shiny inside after 5+K miles and a couple years riding in all kinds of weather. I have the wires going to the motor looped lower than the axle, I expect most people do. While upgrading my wires I used epoxy on the inside of the now oversized wire harness and nearly sealed the axle with the same. All wires going to the motor are covered/not sealed. I did seal the side covers with PTFE/teflon grease and the bike is parked inside heated rooms both at werq and at home. Not only that but the motor is right next to the furnace vent for the livingroom at home so is cycled to 80+ F every time the furnace comes on. I have alot of miles riding in the rain but always park in sheltered usually heated areas. While not all of this was purposely done to preserve my motor seems it has werqed well to do so. Almost fergot my motor cable is long the nearest connections, to the motor, are just below the controller under my seat and covered from rain and spray.

 

[Stevil_Knevil]

Referencing Justin's well informed presentation; besides adding a drip loop and sealing the wires from any potential ingress of water ..I wonder if wire-tying a bag of desiccant (or five) to the stator legs would be useful - if not helpful?

 

[miro13car]

KingFish,
I like your rant at the end of your post, so important, because few people would dare to write this here on this forum.
"it is just plain crappy manufacturing...should not be allowed...etc."
Finally somebody named what should be named more often.
BRAVO
Thank you for naming the things as they are- China brand manufacturing.
Just to put things in perspective.....
E+ motor/built in controller cost at the very least $ 1200 for a reason, no squized undersized wires through centre of axle here,
Rubber seal all around side cover, EACH wire entering front centre hub through seperate hole has individual rubber seals, winding done with real quality enamel wires, real quality permanent magnets no crap, Delphi automotive connectors, and on and on USA manufacturing standards.
How much you paid for your motor KingFish, less than $500?

 

[Kingfish]

miro13car, my 9C hubs were I think were $175, and possibly as high as $215. The E-BikeKit hubs were I think $205 to $225 – I don’t have the figures in front of me; I didn’t think it was terribly expensive. The hubs I modified were brand-spankin’ new with exception to the present E-BikeKit Rear hub which is yet to be upgraded. I used Urethane sealant on the modified 9C axle and flange covers, whereas I used Silicon on the modified E-BikeKit cos my Urethane source hardened and I was in a pinch – however this hub didn’t have profound evidence of standing water unlike the supposedly factory-sealed rear hub.

BTW – I am not asking for money back, credit, or product exchange. I want to be very clear about that, as well as being realistic and pragmatic. I am asking that the suppliers take heed and request that the manufacturers fix the issues on future product as soon as possible. Here’s my list:

• Unsealed stators are unacceptable.
• Motors should be water-resistant, but not airtight; vented in a manner that prevents pressure differential and allows for moisture escape.
• Axle bearings must be marine-grade and sealed.
• I shouldn’t have to cut the connector off to remove nuts and washers (notice that I use the Mini-B USB connector)
• Finally, the motors designed to accommodate Disk brakes: Please make them American and European-compliant so we are not forced to use odd-sized Chinese calipers or file off the nuts of our Avids. Why is the disk mounting interface so uneven that I have to shim it?

Compliments:
I’ve been wielding this stick around and it’s a bit unfair, so allow me to offer carrots… I like the performance of both the 9C and E-BikeKit hubs: When they are in their element and working properly, it’s just plain excitement right out of the box and kick-in-the-butt fun! They are very flexible and work with all sorts of voltages and currents on and off-road. It’s been a life-changing experience that has certainly been contagious to those that have overtly stopped me when On The Road. What could be more thrilling than inspiring the masses? :wink:

Once again, To the Suppliers: Please, I encourage you to address and resolve the motor issues promptly!
Thank you, KF

 

[dnmun]

i always thought that the axle seals on the 9C made them superior with respect to water entry around the axle. it does seem that if the joint where the cover plate fits flush to the hub were leaking the water inside would be propelled by centrifugal force out through the same holes that allowed it to enter.

your hub was one of the worst i have seen, make that a superlative, the best bad rusting. except for C'lytes left sitting outside in the rain.

 

[miro13car]

You want dealers to demand quality from China manufacturers?
You got to be kidding.
The first responds from manufactureres would be that they are going to increase prices.
No way you can have all your suggested improvements and still $200 USA dealer price on even medium size hub motor, even manuactured in China.
Anyway almost sure those improvements cannot be done in existing plants, no machinery
Name of the game in China brand manufature is - use cheapest parts and materials possible/

 

[Kingfish]

You want dealers to demand quality from China manufacturers?
You got to be kidding.
The first responds from manufactureres would be that they are going to increase prices.
No way you can have all your suggested improvements and still $200 USA dealer price on even medium size hub motor, even manuactured in China.
Anyway almost sure those improvements cannot be done in existing plants, no machinery
Name of the game in China brand manufature is - use cheapest parts and materials possible/

When I worked for the toy company many moons ago I wanted to make the batteries fit into the compartment in one direction; make the toy so that there was no +/- pole swapping. It turns out that this can be accomplished for ONE penny per unit; a single wire is all it takes. I told my boss he could take the penny out of my paycheck. Management agreed it was silly to save a penny for the trouble it caused consumers, so I got my wish.

Let’s evaluate the cost of my proposals:

• Sealing the stators is like adding a coat of paint, one thick coat, or maybe two thin ones. The cost is less than a quarter dollar per unit at 10,000 units/month. Gosh, no more rust, and way-happy consumers. Was that expensive to accomplish? No – it’s easy-peasy, and I know China can do it cos we’re already getting starters and alternators from them.
• Venting: The hub covers are cast aluminum. Mod the mold for say - $1000; it’s probably a lot less. It’s just an insert into the mold; they do it all the time. Part is now vented at the seam along the periphery. This is their design flaw: They should eat the cost.
• Axle bearings: There are two bearings per motor. One is a sealed bearing, and the other is not: It uses a rubber seal that costs nearly as much as the bearing. Get rid of the unsealed bearing and rubber seal and replace it with a sealed marine-grade bearing. Money is saved, enough I’d wager to pay for the two fixes above.
• Connectors: Gosh, if they use the USB Mini-B along with an APP clone connector, well – the Mini-B is pre-formed in massive counts, and all they have to do is snake the other end of the cable through the axle and mate it up with the HE sensors. Money is saved cos they don’t have to assemble the Molex connector. And money is saved cos they don’t have to add the nut/washer; they can just remain packaged in a plastic bag tossed into the box. Man – we are saving money left and right! Let’s spend that coin on upgraded phase wires; should only cost us about another quarter dollar.
• Disc Brake interface: Once the unit is assembled, during the functional Q/C test, take 1.5mm off the flange side where the disc is going to mate so that it is FLAT and PERPENDICULAR to the axle. Not a big expense; maybe takes a dollar to do that step, maybe… They have to Q/C the motor anyway so that they know it works, at least – that’s what we do in my country. And as for making the motor compatible with American and European calipers, well we are back to the business of making product that matches our market. If they can’t swim in our pond, if they can’t cook in our kitchen, then THEY NEED TO GO HOME and think about who they are trying to sell to cos we’re not a bunch of idiots…

Or maybe we are! Maybe we are just that weak, stupid, and ignorant. BTW – I have some swampland in Florida I would like to sell to you. And whilst I’m at it, lemme sell you some unprotected motors that don’t exactly fit your standard, and we won’t guarantee quality either, but you are going to buy them cos it’s YOU (the general consumer) that are cheap cos you are eager to put up with it!

I’ve been an engineer for over 30 years. I’ve quit jobs if I thought the client was deceitful. I won’t make or ship shit that I wouldn’t buy. My role in this hobby is to learn. Make something work off-the-shelf. Great, now I’ve done that. Now I am paying the price for choosing these particular motors. But let’s make one thing perfectly clear: What other country is making this class of motor for bicycles? Germany? Japan? United States? Maybe in limited quantities… I struggled to find them. The practical choice came down to Crystalyte, 9C, Bionix, Golden Motor… Not a huge selection out there.

As I said earlier, I’m ready to build my own motor. The links to that study are in my sig. I only want to make two: one for the front, and one for the rear. I want to go fast! I want to be free! If it works and people like what they see, well – that could be another project. 8)

The continuing saga of the motor R&R:

• Second coat of Rust-Mort has been applied this evening. I decided to do this outside under cover from wind and rain. It was far less stanky. I waited a bit before bringing the stators in. The change is not obvious since the remaining rust is slight.
• Also tonight I treated the rotors for the first time. I’ll upload pictures when they dry.

One step at a time.
Thanks for the support and encouragement, KF