9C Motor Rust Removal

[voltman]

Hello All, Voltman here - my first post, thanks for your patience.

I'm about four years into my electric recumbent BikeE (rear shock version). It's a near-perfect machine for "electrifying". Less happily, the BC coast in winter is not kind to Chinese hub motors. I've gone through two Cry'lites and now my 9C has also similarly turned to rust. After getting my pics, ebikes.ca now recommends storing ebikes indoors over NW Coast winters. Sorry. No can do without extending and enclosing my mud room and building a ramp. May have to, yet...)

Speaking of accommodation, while parked in my unheated, 1-side tarped shed, I drape a Harley cover over the front end of the bike and fairing and run a dehumidifier under this drape. Not good enough. The light bulb I used to hang near the hub before seemed to work better. But not 100%, alas...

Once again, I'll be using my trusty (ebay) puller to prise open and drain (!) my 9C. Next I use an electric palm sander (!!)to take the rust off those flat plate stator thingies. No fear. Works great. Then I apply a heat gun (carefully!) to those moist innards until dry. This time, I am going to paint everything within reach with red varnish lacquer (ebay again) used to seal windings in alternators, etc. This ought to help. I hope. (Hint: To avoid crushed fingers and wrecked magnets, use the puller again to slowly and gently re-seat the motor into the hub.)

Yes, I've sealed both covers with silicon and gooped the wires. I've also drilled a single drain hole in the motor cover to "let the water out." (Don't try this in your boat!) A bit of electrical tape seals the drain hole while riding in the wet. If I can ever remember to park the bike with the drain hole exposed and facing down, this might - might - help. Otherwise, I will have to dismount the 9C (or replacement) front hub motor and store it indoors between rides. (Ugh!) A friend with a BMC V2 stored in his wooden shed is still riding with no problems. Expensive. And still iffy. But I'm watching. Recycled my carbon-burner in favour of electric transport, so I really need my ride.

Hope this helps. I hugely appreciate all the advice I've gleaned from these forums. THANK YOU ALL! -Voltman


(Moderator edit: Split this off from Kingfish's rust removal thread,
http://www.endless-sphere.com/forums/viewtopic.php?f=30&t=34135
becuase this one is a different method and should have it's own thread. If the title I gave it is not what you want, feel free to edit the subject of this post and it will change it for you, or post what you want it to be and I'll change it for you)

 

[voltman]

Oops, Voltman Again...

For those interested in the BikeE, that little 16-inch front wheel is treacherous on gravel - which is featured heavily on the rutted rural roads I ride. I learned this by zoning out for a split second and turning too fast into my own gravel driveway - ended up in serious pain for 2 months and just plain pain for another 8... I now wear a terrific Xelement armoured jacket and Mig-21 crash helmet with dual clear and tinted visors. (Fantastic helmet. And yes, ebay for both. I live on an island what can I say?)

I've since modded the BikeE with a heavy-duty mountain bike fork and 20-inch front wheel. Replaced the rear air shock, which was extremely allergic to dirt and mud, with a 3.5-inch taller spring shock to keep the bike raked and more weight on the front wheel. No matter how light a touch on the throttle, wheel spin can become dicey going up steep hills overlaid with fine gravel in the rain... But this sure helps. (I love my internal rear hub tranny too much to give it up.) All in all, though, I gotta say, the shock-equipped, electrified BikeE with 20-20 wheels and good tires is a superb machine.

Now I just have to find a reliable motor. I've had it with Mr. Hall... May go sensorless... What do you think?

Thanks again - Voltman

 

[dnmun]

i wonder if the acetic acid from the curing silicone rubber has amplified the rust problem. acid vapors and high humidity sorta thing.

 

[Kingfish]

Related thread: RUST: DIY Hub Motor Repair & Restoration

In brief, I used common white vinegar (5% acetic acid) to remove the majority of the rust from both stator and rotor. Then I applied a product called Rust-Mort (75% phosphoric acid) in very thin coats, allowing to dry in-between. Rust-Mort ferrets out the last of the rust, and creates a layer of Iron Phosphate which essentially seals the metal from further rusting. The next step is to coat both surfaces with a product called Green Insulating Varnish: This is industrial-grade stuff applied to starter motors and alternators. Lastly, my plan is to vent the hub covers at the periphery with 4-6 small holes which A) arrest pressure differentials that created the problem, and B) allow accumulated moisture to disperse.

It should also be noted that I am upgrading the bearings to sealed stainless steel so they do not rust out again, and the external seal (redundant now) will also be upgraded to Viton which is better suited for the operational conditions.

The final act of this play shall use Urethane sealer and NOT silicone for the hub covers: Silicone is hydroscopic (loves water) and not appropriate for moderate-temperature wet environments (although it's great for motor engines). Urethane is what the body shop people use to seal joints and surfaces.

It’s been a long ponderous repair for me because I don’t have a garage, and it’s been too cold outside for the Rust-Mort to effectively do its’ job. Safety-first: When working with acids you want open ventilation; I can’t stress that enough. It only takes one whiff and your lungs will feel congested for a week.

In closing, you’d think a pragmatic manufacturer would varnish the hubs. Importing inferior product is to me criminal. We need to get actualized and motivated, and vote with our feet. If this crap is allowed to continue I can certainly foresee someone offering a service to weatherproof hubs. It needs doing, and it should be built into the product.

~KF

 

[dnmun]

i saw the phosphoric acid at home depot too. $15/gallon in the paint department near the thinner and solvents.

just recently on CL here, i saw someone was giving away a 5 gallon bucket of the stuff you use to prep galvanized pipe for painting. i bet it would cut the rust off too. but it was free so it is likely long gone.