[remy_martian]

What, no Flir pic of the economizer board and contactor???? Science demands it...
🤓

 

[Zieg]

What, no Flir pic of the economizer board and contactor???? Science demands it...
🤓

Haha, fair enough. I never looked at or touched the economizer last time, but this time I noticed the resistor was way hotter than I am comfortable with. The whole system was drawing 0.65A according to the power supply, and the voltage drop across the resistor was 5.85V, meaning the resistor was dissipating about 4 watts.. That matches the math, and since the resistor is rated for 10 watts I thought nothing more of it. However, the FLIR (and my fingertips!) tells a different story... I just tried turning the voltage down on the power supply and the contactor will close with as low as 7.4 volts running through the system. I'll have to do a few back calcs (and test it without the economizer board) and then I should be able to select a higher ohm resistor that I'd still feel comfortable using.

At least the contactor is running much cooler as expected (despite the temperature in the room being higher than it was during my first test).

 

[remy_martian]

Two of those boards in your car will cost you 170 feet of range due to resistor losses...
🤓

 

[Duncan]

I am a maverick about suspension design - as far as I am concerned the "roll centers" are complete bollocks

What you need to look for is the angle recovery so that if the car rolls 5 degrees the tyres are still vertical to the road

Saying that my car with the battery on the floor simply does not roll much at all

When you know the final corner weights then you can calculate the required spring rates - I'm using 70 lb/in on the front and 100 lb/in on the back
and I expect your car to be considerably lighter

 

[Zieg]

Heh, yeah, it seems like a pretty polarizing topic - whether they matter, and if so, how to calculate them and what to aim for. I kind of split the difference and made sure it looked okay, but didn't go to any great lengths to optimize for it.

And on that note, the above numbers are with 0.5 deg static negative camber. From what I gathered from my textbooks, a slight bit of positive camber on the outside wheel should be okay. I don't want to add any more static camber or camber gain in bump, for fear of having traction issues.

As for springs, yeah, I'm going to have to revisit the front and rear. I tried hard to mount the rear coilovers directly to the uprights instead of the wishbones, but there just wasn't enough clearance. Now that they are on the wishbones the motion ratio is different, meaning I have more travel than I want, and a much lower wheel rate for the same springs. Thankfully, I do have some stiffer springs that should get me back to a similar wheel rate, so I'll use that as my baseline before ordering new springs all around. I don't think the extra droop travel will be a problem but I will need to machine some bump stops so I don't put a wheel through the top of the fenders...

 

[Zieg]

Alright, I think I finally have enough to post a meaningful update. My son was born at the end of October and is doing well, and recently I have been able to spend a bit of time picking away at parts of the conversion. I have the whole ICE drivetrain removed and now I'm free to start cutting things off the frame that I don't need anymore (motor mounts, rear suspension mounts etc).

So starting with the rear suspension, since the car had a Ford 7.5" live axle, I needed to design a complete new double wishbone setup. I dusted off my suspension design books and my design notes from when I did the front suspension and got something that looked pretty good. I'll have to shorten the Leaf axles, not sure yet if I want to cut and weld the axle, or chop one end off and machine new splines. Probably leaning towards the latter, if I can get the right tooling (and fixturing)..

Anyway here's what I managed to whip up:

The hubs are OEM Leaf but I did press out the metric studs and replaced them with longer, 1/2" studs so they will match the front (and my nice spline drive lugs). Really glad they were the same 5x4.5" bolt pattern. I will need to machine new hubcentric rings but that's trivial since the center bore is smaller on the leaf than what my existing wheels are.

The uprights I had to send out and oh my were they expensive, but I am very happy with the result.

For the cooling system, I went ahead and got a nice electric water pump and a coolant reservoir from a Chevy Volt, along with the matching 5 psi vent cap. There's nothing but aluminum touching the coolant in the leaf motor/inverter so I'm just going to run dexcool since it's the OEM coolant for the batteries. This handy chart goes over the major differences in types of coolant for anyone interested: https://images.oreillyauto.com/uploads/pdf/ad/SD_672 AFZ Comparison Chart-1.pdf

I am dithering a bit about the exact arrangement of components, but so far this is my best idea. The highest points in the system would be the 19 psi rad cap in the front of the car, and the reservoir in the back (which would be the absolute highest point in the system). It'll also be quite easy to reconfigure this if needed.

 

[Zieg]

Now as for the gearbox, as I mentioned in another thread I have been working on modifying it to run in reverse more reliably. At least I hope.

From what I can gather, the differential gear draws oil up and throws it into a little reservoir, where it then drips onto the jackshaft and I believe the helix direction then directs some oil into the bearing on the motor side of the box. Then, when the reservoir is full I believe the differential gear starts throwing oil between the bottom of the reservoir and the top of the jackshaft, where some of the oil that's travelling along the side walls is able to get to the back of the other gears via little pockets in the casting. Like so:

(Note the cavity above the reservoir is actually baffling for a vent. There is a matching cavity on the other half that allows air to pass through a labrynth and finally to a little breather hole that faces inside towards the motor for whatever reason.


So I figured I would install a scavenge pump that draws oil from the lower drain plug and feeds it back up to that top reservoir. Only problem is, the oil dripping through the single hole in the bottom only hits the jackshaft, and in reverse it wouldn't even be kicked in the right direction. So I set about adding some extra holes to the reservoir in the hopes that the oil will run down the side walls and into the same pockets in the casting. I also carved a small channel to try and help guide the oil even more. This was all done with a drill and a ball end mill on a dremel. Photos of this to follow later.


Then I had to add a port to get the oil into the reservoir. After some consideration I decided the best way in was through the side wall on the side opposite the motor. I stuck a neodymium magnet to the inside and outside to try and work out the best location to drill. It wasn't an exact science but it worked out. First I traced around the magnet, took it off and used the old eyecrometer to locate the exact center of the circle, then drilled a small hole to check that I'd be happy with its location on the inside. Hole location looked good, so I clamped it back on the mill, picked up the center again (this time with an actual center finder) and did a little spot face with a 3/4" end mill. Mainly I just wanted to nip off the edge of the fillet leading up to that mounting hole. I was pleasantly surprised to see the surface was also pretty parallel with the existing machined features.

Finally I drilled the hole and chamfered it. I didn't realize the casting was quite so thick here!

Finally, tap it 1/4 NPT using a spring loaded tap guide to keep it straight.

Side note, I read somewhere that if you stop a properly made tap with 6 threads still showing, you will have reached the correct depth. I checked this very tap against a proper thread gage once and it was bang on, so that's my goto rule of thumb from now on.

For the pump, I wanted to find something inexpensive but reliable, and with a current draw and flow rate far less than that of your typical transfer pump. I eventually found that certain BMW models used an electric pump to feed the oil cooler on either the engine, transmission, or both. They can be had cheap on eBay if you search for part number 11417834496 or terms like "M5 oil cooler pump".

This is what it looks like inside:

And if you carefully lift the tabs on the plastic housing, it can be pried off (there will be resistance due to an oring) and you are met with this:

Google that part number and you will find a nice datasheet stating it is rated for 2.81 amps continuous. Perfect.

So then I needed a mount for the pump since it has a flange and custom oring. I had to offset the holes a bit so I could use a 1/4 NPT outlet and 3/8 NPT inlet. Seemed to work out though.

And the mostly finished product. I will add mounting holes for it later once I figure out exactly how I want it.

 

[Bratitude]

the newer leaf gearboxes use sealed bearings, worth swapping over to with running the gearbox backwards

 

[Zieg]

Oh, any idea what year that started? I can't seem to find any photos online. I also had trouble finding a sealed bearing that was rated for the same RPM as the motor, it'd be interesting to see what they used.

 

[Bratitude]

Oh, any idea what year that started? I can't seem to find any photos online. I also had trouble finding a sealed bearing that was rated for the same RPM as the motor, it'd be interesting to see what they used.

see this thread here Voltswagen T2 -76 - Page 4 - openinverter forum

 

[Zieg]

Interesting, thanks. Still not sure what year that started but I believe mine is from a 2015 so it must be after that. Between the two numbers he lists and my existing measurements I'm pretty sure I can get my hands on a set. Then I'll have to take before/after measurements to see if the shims need adjusting or not.

 

[remy_martian]

"Sarah" is she, not he.

 

[Zieg]

Oh got it. Saw the username Cera but didn't make the leap.

 

[remy_martian]

She started a thread here, but we apparently got cucked for the intellectuals over there 🤓

 

[Bratitude]

Interesting, thanks. Still not sure what year that started but I believe mine is from a 2015 so it must be after that. Between the two numbers he lists and my existing measurements I'm pretty sure I can get my hands on a set. Then I'll have to take before/after measurements to see if the shims need adjusting or not.

ill shoot arlin a message, he did a bunch of research on what bearings to use for his dual leaf motor crx. (yes that arlin from axiom) he found the correct fit type, as the expansion and contraction of the bearing on the shaft and case, from heat, is a very important metric to get right.

also silicon nitride ball bearings... because arching

 

[Zieg]

Thanks, let me know if he gets back to you. I scoured bearing catalogues for hours last night but didn't come up with much useful. There are some bearings available with non contact seals that meet the speed requirement of the input shaft, but unsure if the ATF could still get in there and wash out the grease. Unless they figure you're okay to exceed say a 7k rpm limit on a contact seal bearing, if it's being somewhat continuously splashed with ATF?

The real pain in the piston is the motor-side input shaft bearing. Seems to be called a 62/32 trade size (32 x 65 x 17) which is not listed in a bunch of the big names' catalogues. I went back and tried Googling the trade name of one of the bearings listed by Cera (or Sarah or whatever) and the LA suffix did not get a lot of hits. What I did get was a listing from a Slovakian supplier called AKE, but that doesn't make a ton of sense if the bearing in the picture also has 'Japan' embossed on it. What's worse is the AKE catalogue doesn't list the 62/32 bearing. Makes me wonder if maybe the cases were bored larger when they switched to sealed bearings.

I'd be real interested in whatever Arlin has to say about all this! Especially the tolerances for d and D.. really hoping those are at least standardized.


In other news, I'm not so sure about my plan to adapt the 1-1/4" hose barbs from my Mitutoyo radiator down to the 3/4" hose that will run to and from the water pump. What I wanted to do was machine an aluminum plug that was tapped for 3/4 NPT, lightly hammer it into the ID of the rad's barbs, then use some Alumiweld brazing rod around the perimeter. Problem is, the barbs aren't super round so it's hard to know what size to machine the plug to, and the hole size for the 3/4 NPT is very close to the OD of the plug. My tests with the Alumiweld have also been .. less than encouraging. Summit has some reducer elbows but that changes my planned routing. Might have to swallow my price and take it to someone with a TIG. Sigh.

 

[darko]

This is probably a dumb question, but just wondering what would be the harm in just filling the gearbox up with enough oil to lube all the bearings regardless of direction? I'm assuming the issues would be frothing, loss of power, and maybe heat? Perhaps the axle seals may leak with being constantly under pressure?

 

[Zieg]

Yeah, probably a significant parasitic drag, frothing and heat. Definitely don't want that jackshaft immersed in oil at the speeds it's going.

 

[Zieg]

Well I haven't been able to find part numbers for all four of the sealed bearings so for now I'm going to carry on as planned. Can always swap em out later.

Here's what I did to hopefully get some more oil at the bearings in reverse operation. This was all done by hand using a 1/8 ball endmill in a dremel and a 1/8 drill bit (in a drill!). I used the dremel to create an indentation, then drilled through with the bit, then just carved myself a little channel, for all the good it may or may not do. Could always cut 'em deeper later if I want.

I'm also trying to work out a good way to feed a speedometer signal to my dash. Looks like the Openinverter may not have a great way to output pulses with a frequency that changes proportional to speed, so I'm currently looking at ways to mount a hall sensor in here. The OEM sensor for my old motorcycle engine just reads the teeth on one of the gears fixed to the output shaft, and the number of pulses per wheel rotation is actually pretty close to the same with these gears. I can calibrate my speedometer to within a certain range of pulses plus or minus, so an exact match is not necessary. Still doing research on this, but if I'm going to be doing any more machining on this thing I'd rather do it soon so I can button it back up and get it out of the way...

 

[Bratitude]

I'm also trying to work out a good way to feed a speedometer signal to my dash. Looks like the Openinverter may not have a great way to output pulses with a frequency that changes proportional to speed, so I'm currently looking at ways to mount a hall sensor in here.

just setup rpm to send over can in the web interface, then have a Arduino with a can transceiver and a fet converting it to the pulses for the gauge?