Oil cooling your hub- NOT snake oil!

[d8veh]

You can get suitable brass tube from a model aeroplane shop, where it's used as fuel pipe. You'll also be able to get a small filler bottle and some silicone tubing to go between while filling. A few dollars max.

[dfar]

you can purchase a couple brass fittings from the local hardware store and install them so you have a nice threaded plug that you can remove for filling the hub.

use ATF gasket sealant around both sides of the covers. I have found 100ml or so of ATF to be a good amount of fluid to use.

1/2 (i believe) brass fitting, notice it is internally threaded to receive a plug. The cover was drilled and then tapped.

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the plug that will screw into the 1/2 brass fitting. A hole was drilled in the center large enough to fit a small piece of tubing (the tube found on the end of WD40 cans) the hole is just slightly small and the tube is pressed in tight.

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same as above different angle

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view is from the interior portion of the hub cover. the plug is installed into the 1/2 brass fitting. everything is cut so that it does not protrude past the cover.

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1/2 brass fitting without the plug

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[shorza]

Looks perfect. How did you get to first brass fitting in there? Did you thread tap the cover?

[teklektik]

you can purchase a couple brass fittings...

This is a clever concept to get more robust threading for a filler plug instead of the using the aluminum side cover directly. Even if the plug adapter is ground/cut thinner for clearance, the resulting threaded insert should give good service.

(BTW - How about posting pics [in-line] instead of just as attachments? ...much easier to view... )

[dfar]

(BTW - How about posting pics [in-line] instead of just as attachments? ...much easier to view... )

I was not aware I could do this, could you direct me to where I could learn to do this?

Thanks

edit (thanks for the instruction teklektik)

[teklektik]

I was not aware I could do this, could you direct me to where I could learn to do this?

Sure -

1. go back to your original post with pics as attachments and click [EDIT] in the upper right corner.
2. Position the cursor in the text somewhere - let's say at the end in this case.
3. Go down to the bottom where your attached image files are listed and press [Place Inline] under each file.

If your image is greater than 250K in size, a smaller representational image will be inserted that will bring up your original large image when clicked. You can insert a link in-line for any file type - PDF, etc.

[motomech]

This is my idea for a vent hole.

The little plastic tube fits onto a nipple. Then the tube loops around the axle so that the spinning of the axle should spin any fluid back towards the opening.

Why not put a couple very small vent holes inside the threaded portion of the free wheel mount and let them continually lube the DNP POS

[parabellum]

Why not put a couple very small vent holes inside the threaded portion of the free wheel mount and let them continually lube the DNP POS

Why not just damage a shaft seal lip on threaded side (Little hole done with the needle) ?

[motomech]

Seriously, just drill though the seal. I used to drill them and insert a wood screw to pull them out all the time as a motorcycle tech.
Easy enough to patch or replace the seal if it doesn't work out.
Speaking of "working out', presumably, if some oil did pass from the motor into the inner mechanism of the free wheel, eventually it would escape though the gears and onto the chain. A good thing or a bad thing, depending on one's perspective.

[Stone Meadow]

Here's another option for venting the hub. Install on of these 'differential vents' as close to the axle as practical. That's a sintered bronze insert to permit pressure equalization, but it's essentially leak-proof.



Just four bucks from Hawaii Racing.

[shorza]

Ooh, I'm interested. Has anyone tried this yet?

[Spicerack]

My concern with a sintered bronze fitting is that the oil will wick through the sintered bronze and leak more than a tube or small hole as previously described. Remember the KISS principle people

[Stone Meadow]

My concern with a sintered bronze fitting is that the oil will wick through the sintered bronze and leak more than a tube or small hole as previously described. Remember the KISS principle people

Fair enough. I was only thinking that the breather plug might allow equalization without the danger of admitting water and other shyte, while not leaking any more than a plain hole.

[hjns]

i'm thinking 150C is the absolute limit, for the halls, varnish etc. i have the sense that the oil will take the motor much longer to heat up, but eventually it will get hot, and probably stay hot.

I think only adequate testing will tell. I am still struggling to find time to rewire my 9C and add the thermistor. But one of the variables to be tested under aircooled versus oilcooled condtions must be how much abuse the motor takes before going above 90oC, and how long it takes to cool down again. In other words, expose the motor to a standardized route with a known increase in altitude at a fixed current and/or fixed velocity. Once the motor is 90oC, then measure how long it takes for the motor to cool down to an arbitrary temperature (50oC ??) during a low amp high speed setting (aka WOT with the wheel in the air), after which one can safely start pushing it again.

We can all predict that the oilcooled motor will take longer to get to 90oC. However, it will be very interesting to see how fast it cools down again as compared to the aircooled motor.

[GCinDC]

This is my idea for a vent hole.

The little plastic tube fits onto a nipple. Then the tube loops around the axle so that the spinning of the axle should spin any fluid back towards the opening.

hole at angle:

1/4" tube i think, jb welded into place inside

and outside (taped until jbweld underneath dries)

after building the (big heavy amp sucking) wheel

i tested the temps on an easily repeatable route, and will update this with data from oil filled version...


lot more detail about my ride in my thread.

[teklektik]

I'm thinking that the tube should spiral from the side plate inlet inward toward the axle where the open vent end should be located, not outward as shown. The spinning motion of the wheel will cause oil in the tube to move outwards toward the rim so the end of the spiral tube most distant from the axle should dump into the hub.

[GCinDC]

we shall see!

suggestions how much oil to put in? i've got a quart...

i'd kinda like to pour it in and see it before sealing the side cover. get an idea of the volume. could be messy tho..

by injection, i'm not sure i'll ever know. and there will be counterpressure?

[itchynackers]

You probably won't get a good idea before sealing it up. One think I considered was to cut a slot in one of the covers, and then insert a clear window in its place, to use as a fill gauge. Even if it was a 1/8" drill hole near the perimeter covered with clear plexi, you would be able to tell how full you were just by rotating the "window" to the right position.

[teklektik]

Fill it like a car differential/transmission: Use the mating brass plug fill solution proposed by dfar but using your vent. Just rotate the wheel so the fill plug is at the desired depth and fill until it overflows. Use a Marinade Injector (eBay 'Marinade Injector') so the job goes quickly.

He's got some strangely encoded images that the forum won't display inline, but you can view them if you click them. Here's his first photo (re-encoded):

I might put the fill plug as far out towards the rim as possible so it can be used as a drain plug as well...

[grindz145]

badass!!

[csm]

It is good to see more people discover and document the benefit of oil cooling a hub. I predict it will become the standard in the near future.

Pioneering work was done in this area by Bowling Green State University (BGSU) Professor Anthony Polumbo in BGSU Paper "PowerDenseElectricMotor-BGSU-01566299" (0-7803-91 45-4/05/$20.00©)2005 IEEE) where they increased the power of a NEMA 215 Frame induction motor used to power a bus from approximately 10Hp to 100Hp. Not all the improvements were from oil cooling, but it sure enabled much of the increase in "Power Density."

Sadly the Electric Vehicle Institute at BGSU has been dismantled and the staff scattered... right when we on the cusp of electric propulsion. They had a great staff and great vision, just too early for stable funding...

They still seem to maintain a website. http://www.bgsu.edu/colleges/technology/EVI/

Which project was it that they used oil to cool motor?

[GCinDC]

[GCinDC]

w/o oil it took me 1 minute to get up to 70C.

w/ oil, it took 15 minutes of pulling mostly 4kw, heavy starts, stops, bad throttle.

got some weird cut outs tho. almost like hall dying, but power resumed right away. happened a bunch of times. not good.

also, i was VERY glad i removed rear caliper, as the seal on the disk side blew and a bulb of oil appeared. not sure why vent didn't work!

perhaps should have waited longer for sealant to dry. i'm used to painting caulking while wet...

i did some tests with round tupperware, and figured out that 1/4 full put oil at a good level:


i hated the thought of not knowing how much was in there, so decided to fill it halfway, then siphon out half of that. i ended up putting in 400 cc total, but 50cc probably leaked out axle. i made the mess so you won't have to...

and 350cc is still too much, if oil covered my vent hole, there would be too much pressure in there.

some of the work:

[hjns]

Thanks. Very good info. I do worry about the cutout. Hall issue? Does the Clyte also have a separate hall pcb?
I will cover my halls / hall pcb with silicon muck.

[teklektik]

... as the seal on the disk side blew and a bulb of oil appeared.

What does this mean exactly? Did the lip/retaining spring deform and actually blow out or did it just leak?

The oil seal lips are very easy to damage - normally you would never know on a hubmotor. However, if the covers have been mounted up without lubing the seal and shaft to protect the seal prior to assembly, it could have been damaged - perhaps even in a previous assembly operation. If it has no internal coil retaining spring, then it's unlikely to provide a good enough seal - replace with a standard double lipped seal of the same size.

... if oil covered my vent hole, there would be too much pressure in there.

Not really. Once vented, there should be negligible pressure differential - the vent will do its job - if it's submerged, oil will be expelled to equalize pressure.