Oil cooling your hub- NOT snake oil!

[motomech]

As an Ex Japanese motorcycle mechanic, my favorite sealant by far is the gray, semi-drying, non-silicone based stuff sold by the manufacturers.
Various names, Hondabond, Yamahabond, etc.
All the same stuff and it's perfect for that application.

You'd think there would be "improved" stuff by now, but you're right, Yamabond worked great on motor side covers and gearcases.

I guess one can't improve on perfection.

[GCinDC]

so if my uphill commute gets a vented 9C up to 130C regularly, would it be a good candidate for oil cooling?

i picked up some auto/marine sealant and dextron III, but am just wondering if the oil can handle that heat, or if it's better to stay vented...

keeping the motor at 80C sounds nice, but it's not gonna happen!

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 rode it to work today, which is 22km. The hottest it got was around 90 celcius. It was very interesting to see the temperature on the windings go up by a degree or two a second whilst accelerating from standstill, then drop almost as fast once up to speed and on WOT. Most of the time it was running at 75 celcius.

andynogo, could you get it hotter than 90C, doing rigorous uphill trail stuff? how would it react? what do you consider the absolute limit?

[wiuhh]

[quote="GCinDC"]so if my uphill commute gets a vented 9C up to 130C regularly, would it be a good candidate for oil cooling?

i picked up some auto/marine sealant and dextron III, but am just wondering if the oil can handle that heat, or if it's better to stay vented...


most car transmissions run much hotter tho they are cooled by the radiator. i doubt the temp will be a problem but if i understand what you guys are doing(new to ebike) you definateley want to vent because of tempature changes causing fluid expansion. most (all i have ever seen) transmissions/rear diferentials are all vented.
probably not relevant but you might be more worried about foaming which also shouldnt be a problem because there should be enuff anti foaming additives in any atf(eduacated assumption) for this application. as well as your not relying on the oil for lubrication so your only risk is loss of cooling. tho a long trip at high enuff rpms if theres any cake mixer scenario(for lack of a more common term) going on with any oil it can turn all your oil into useless foam. side note id also recomend you seal with rtv made to replace a transmission pan gasket(put on wet and filled with atf) you have to get from the auto manufacturer name brand silicons wont seal as well with atf. been out of the field for a lil over 10 years but dodge rtv was by far the best for atf. (no pan gasket all rtv)

ps luv this thread i hope you guys do well cuz there will probably be a bunch of us plagerizing your design so try and do a good job lives are at stake

[GCinDC]

doh, i hadn't realized there was another thread.

the rest of my q's were answered there, (here specifically), but start at the top. good stuff.

[Spicerack]

Totally forgot to give you a reply yesterday but looks like you're on track. Yes, your 9C is most definitely a good candidate. Don't forget my figures are with a damaged motor- I cooked the windings so it's making alot of excess heat now. Having said that, I haven't got it above that 80-90 celcius at all but I don't have any long hills around here. I have a new set of windings now so will get onto fitting it and posting up some new results.

[sn0wchyld]

What I take from this is that we need to find out what type of neo magnets they use to make these hubs! Until then, I think I can hang out in the 80c zone. With my air ventilated 9c I get it up to 120c pushing 4kw. With my new H series clyte in an oil bath I think I can do 4kw and stay at or under 80c.

edit: I just had one more thought: does the irreversible damage stack? As in at 100c you have 2% damage. If you take it to 100c again, do you get 2% MORE damage?

check the links on p4. to answer your question... no. you loose magnetisation, but gain heat tolerance before any further degradation will occur. basically you end up with a higher KV motor. You'll get less torque for a given input, and slightly lower efficiency during acceleration (and slightly lower peak efficiency too), but a higher top speed as a result.

More than likely the cheapest grade N magnets are being used. Otherwise there would be some boasting of the grades used. Probably N35s.

from memory when I played around with a calculator on that site I linked to (on p4 I think..). temp rating actually went down with higher grade magnets. so N35's handle more heat than n40's can, Ill have to check though. this could also be why repeated overheating of magnets doesnt degrade them further (for the same max temp), as your effectively taking a n40 to a n35, or n45 to n40. In both cases your magnets are weaker, but have a higher temperature tollarance before further damage will occour.

The other major factor that affects magnets heat tollarance is their dimensions. it seems that long fat magnets like those in 80100 motors have higher temp ratings than large flat thin ones. Comparing the size of magnets on my HT with those on their site gave me a rough number of about 90-100deg before damage, though I think I'd keep it below 80 as much as possible, just to be safe.

[auraslip]

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.

[fechter]

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.

That looks like it would work (but I think you show the wheel direction backward - I get the idea). The tube might even fit inside the cover. You could use 1/4" copper tubing and a 90deg compression fitting at the end.
The open end should probably be closer to the axle than the place where it comes out so centrifugal force will help push the oil back to the motor.

[cal3thousand]

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.

That looks like it would work (but I think you show the wheel direction backward - I get the idea). The tube might even fit inside the cover. You could use 1/4" copper tubing and a 90deg compression fitting at the end.
The open end should probably be closer to the axle than the place where it comes out so centrifugal force will help push the oil back to the motor.

That's how I read his drawing. The hole is closer to the center than the rest of the tube, which will allow for a centrifugal effect to keep the oil inside by flinging it away from the hole. The tube wouldn't even have to travel much, maybe 1 radian would be enough.

Great idea auraslip!

[shorza]

What's the smallest diameter copper tubing? maybe 2mm?
Could this be epoxied in like the diagram above, and double as a filler hole?

[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.