Another attempt at liquid cooling...

[itchynackers]

Mr. Methods shipped me a new 9c 6x10 rear motor which arrived Thursday. I currently have a 9x7, and an 8x8. Figured I'd give lower speed, better hill ability a try. Also I've been seeing a couple threads having success at liquid cooling, so I figured why not. So far I've...

1. Bench tested new motor. It works.
2. Tore down new motor.
3. Cut phase/hall wires and ripped them out.
4. Epoxied & baked magnet ring.
5. Epoxied & baked windings.
6. Installed thermal sensor with high temp silicone sealant between 2 phase wires at the windings.
7. Drilled axle out with 5/16" bit.
8. Stripped 10awg teflon coated wire & heat shrunk each wire.
9. Heat shrunk 3 phases & 7 30awg teflon coated wires and inserted through axle.
10. Soldered all wires inside motor with silver solder (higher melting temp).
11. More silicone sealant around wires near axle to prevent any liquid ingress/egress.

Yet to do:
12. Install tiny vent tube for breathing/filling of ATF fluid....Edit: DONE
13...Did I forget anything?

Pic of progress so far.


If all goes well, hopefully I'll be able to report temps. Trying to decide if I want to run without fluid first (to get a baseline temp).

Edit: Probably should get a no load current value first also. Although, I run a heavy tire/tube combo, so it may be skewed up a bit.

[Spicerack]

Looks good. Definitely get baseline figures first- no load amps dry/wet with wheel installed on bike, wot amps on a set course at max speed dry/wet and power consumption, along with temps! I look forward to seeing results on a DD- my geared has benefitted from the oil cooling and I'll also chuck up decent results when I change over to a new style stator.

I'll also be doing pretty much the same thing with my 9C 8x8...

[ohzee]

That is one pretty motor nice work.

[itchynackers]

Thanks. I'm on hold until I get the brake disk. I need that so I know where to put the vent. It should arrive Friday.

[flathill]

If all goes well, hopefully I'll be able to report temps. Trying to decide if I want to run without fluid first (to get a baseline temp).

Edit: Probably should get a no load current value first also. Although, I run a heavy tire/tube combo, so it may be skewed up a bit.

Excellent work! What kind of epoxy did you use? Please baseline the no load and temps. This will be great data. Thanks

[Spicerack]

Just make sure the vent hole is further out from the axis than the disc mount/holes. I thought about drilling from inside the axle hole down into the cover but if any oil leaks out it will end up on the disc.

[parabellum]

Thanks. I'm on hold until I get the brake disk. I need that so I know where to put the vent. It should arrive Friday.

I strongly recommend to make the vent on chain side, there is no way to make it leak proof and oily disk brake is bad thing.
Few ideas.
Tube is installed in shown angle.


Tube is glued in with epoxy (behind 7 speed hub), standing out ~5mm from inside and outside (less oil leakage).

Oil feel opening is on disk brake side, as near to center as possible to avoid any contact with brake caliper. I used aluminum screw with rubber seal and lil bit of lock tight.

[itchynackers]

The "plan" is to try to create a breathing, but leak proof vent. So I want to try on the disc side. This is only because I can get closer to the axle, while still being able to access the vent at any time without taking off the disc or cluster. I'm still trying to find a suitable material to place inside the vent hole. Something that will breathe, and also won't absorb fluid. I'm thinking something similar to a brillo pad.

[parabellum]

The "plan" is to try to create a breathing, but leak proof vent. So I want to try on the disc side. This is only because I can get closer to the axle, while still being able to access the vent at any time without taking off the disc or cluster. I'm still trying to find a suitable material to place inside the vent hole. Something that will breathe, and also won't absorb fluid. I'm thinking something similar to a brillo pad.

Good luck with your plan, hope it works.
This was my 3rd try with best result so far.

[itchynackers]

I looked at the blue coating. It was VHT brand high temp caliper paint good to 482C. Also got the vent installed. Used dp420 epoxy. We'll see if it holds. Also I'm trying a piece of air breather foam material (from my air compressor) as a vent insert. I wedged it in the vent with a toothpick. Seems to hold pretty well, and still breathes. I just have to pick up some ATF fluid and seal the left side cover. What has everyone decided is the best to use, Dexron 2,3?

[Spicerack]

The cheapest ATF will work the best! No difference for our purposes.

[fechter]

Some quick reseach shows our own AndyH has looked into this:
Lower numbers should have less windage loss. Ford Mercon SP looks like the winner.
I didn't find data for the standard stuff, this all looks like synthetic aftermarket brands. At extremely low temperatures all of them get thicker. It might be worth draining the oil in extreme cold.

(Automatic Tranny Fluids - except for Redline D4 dual-use)

VI Vis@40C Vis@100C
.............8.3 = Honda CVT Fluid
.............7.6 = Mobil 1 Synthetic ATF

198 33.5 7.5 = Redline D4 ATF Dexron III / Mercon / API GL-4
.............7.4 = Mobil 1 Synthetic Dexron/Mercon
197 32.5 7.2 = Redline Synthetic ATF Dexron II / Mercon
.............7.1 = Mobil 1 Synthetic Multi-vehicle ATF
138 40.5 7.1 = AMSOIL Ford type F auto trans fluid
168 37.4 6.8 = AMSOIL Automatic Transmission Fluid ATF
..........5.5-6 = Ford Mercon SP

[itchynackers]

Hopefully I'll never hit 100C, so I guess I should be looking at the Ford stuff like you mentioned. Awesome! Thanks fechter.

[itchynackers]

Ok, just got the motor all put back together. Dammit if I didn't forget to get no load current without fluid first. I guess if I ever drain it, I'll have to post up with the results. I put 300ml of Valvoline Max Life ATF in there. Vent doesn't seem to be leaking during bench testing. I did get a bit of potentially useful info tonight. At 116.0V resting (partial charged 30s lipo) I saw 2.16 amps at 115.4V sagged. Also, I haven't quite got my tire balanced on the rim, so the current may be skewed up just a bit. I'll try to balance the tire tomorrow. So does this mean I have V=IR, 0.6=2.16(I), I=0.28 ohms of battery resistance?

Weather permitting, I'll ride the same route I usually do. I'm familiar with what temp ranges I've been seeing at the end of ride. It should be apparent very quickly if this liquid cooling works for me.

Edit: The no load test was at ambient 55.5F.

[grindz145]

Sweet! What current limit do you plan to run? You won't necessarily be performing a before and after test, but if we get a good idea about performance, it should be pretty easy to know if there is a drastic cooling performance increase. I'm Very interested in this

[itchynackers]

Not quite sure yet. On the motor I took off (beefed up 9c 8x8) I ended up running 40a battery current. Although, for a while, I ran peaks of 90a, but that was on 25s lipo (102.5v hot). Just didn't seem like I was getting that much better acceleration, so I backed it down. Just this week, I switched to 30s (123v hot), and the end of ride temps were definitely affected. Before I got about 70-82C temps. With 30s, I'm getting 80-92C. And these runs were not pushing it 100% from stop lights. Usually I ride this route (6.5 miles) to work. Generally, I arrive home at night hotter than morning, since I'm riding into the wind heading home. The last time, I hit 102C with 30mph head wind gusts. I rode at about 30mph and still hit 102c.

I think I'll try 40a peak for a bit (about 4800watts). If I see good results, I'll up the amps a bit.

[Spicerack]

Nice, so just a little bit hotter than mine which is running at 1300W. Shows how toasted my windings are! Can't wait to get my new stator in. Also a good indicator for my 8x8 9C... better get that all fixed up I guess!

[itchynackers]

Ok, for those interested, I have a few results.

6.5 mile usual ride to work.
Ambient temp = 5.5c
Ending (highest) temp = 50.1c (way below the usual range of 70-92c)
Used 51.2 wh/mi
51 amps peak

Took about 3 minutes to write down the results, then I rode home right away.
Starting temp (cools down quicker than before) = 42c
Highest temp (during ride) = 67.2c
Totaled 57.9wh/mile for the total of 13 miles

Notes: I pushed hard on the way home, which I never do, and still didn't reach a temp I normally would see.
My tire is still egg shaped, must fix.
Had some minor fluid leakage. Got about a drop or two out of the vent. Didn't get on the brake rotor. I'll have to work on that. Also, I must not have sealed the inside axle hole very well, since there were a few drops coming out the end of the axle. I'll have to fix that if I crack the motor open again. Also, there seems to be very minor leakage out a couple cover screws. I'll try thread locker or silicone sealant to seal those up. All in all, I'm quite happy and will turn up the amps a bit. I'll have to start monitoring controller temps (I have a habit of not doing that since it hasn't been an issue). Once I get the minor leakage worked out, this should be more of a worry-proof system.

[auraslip]

Good work!

[Spicerack]

Perpex window in a side cover for level checking, live with minor leaks and top up when neccessary. Easy!

[itchynackers]

I had thought about a clear window for level monitoring! Just have to think about it a bit more to work out some details. Also, it looks like I didn't tighten down all the cover screws, so that may have been why I got some minor seepage out a couple screws. I noticed it when I went to seal each screw with silicone sealant and none of the screws were tight, whoops. Anyway, the silicone is drying for 24 hours. Should be ready for a retest after work today.

Also, I'm thinking I may leave the vent hole unobstructed. It's only a 1.5mm hole to begin with. If I stick a small piece of plastic in there (that still leaves room for airflow) it should all but stop any drops from escaping. We shall see.

[itchynackers]

Ok, tight screws do make a difference. No leaking there at all. I'm still eyeing the vent hole. Got a half drop from it, so I put a piece of insulated wire in the hole after pulling out a few strands (to still allow some air flow). That seems to have worked. I think that is it! If I could just get my damn tire to inflate round instead of oblong, I'd be 100% happy. Incidentally, I checked my top speed after charging to 4.1v/cell and got to 42.8 on 30s lipo with lyen controller programmed to 100% throttle (haven't done 110 or 120% yet).

[Xanda2260]

Thanks for the detailed write up. I really want to try this on my 9x7. Would you mind posting a pic of your vent hole + wire mod? I'd rather not have oil all over my frame after each ride!

Many thank yous!

[itchynackers]

Looks like I'm still getting just a teeny tiny bit of oil out the vent hole for my 6.5 mile ride. Maybe 1/4 drop. I'm still working on something better.

[parabellum]

Looks like I'm still getting just a teeny tiny bit of oil out the vent hole for my 6.5 mile ride. Maybe 1/4 drop. I'm still working on something better.

Pictures?