[WIP] Daihatsu Hijet kei truck conversion

[maboyce]

Hello everyone, I would like to introduce my (potential) project, a 1997 Daihatsu Hijet truck I imported from Japan a few years back.

It's a lot of fun to drive and just as useful as most modern pickups as far as carrying things in the bed goes. This is the fanciest version they sold at the time, with an automatic transmission, air conditioning, and the 'big' twin-cam engine producing 32 kW and 59 Nm. It will happily travel at highway speed (100 km/h) for hours even though the bottoms and backs of the occupants will not.

I've always wanted to convert a vehicle to electric, and this feels like a great candidate. As small as it is, it's mostly empty under the bed. The engine is under the seats, and aft of that the narrow transmission and driveline run down the centre to the rear axle. I did a 3D scan of the underbody and removed the drivetrain and fuel system:

The big challenges to the project are two:

Weight - the stock empty weight is 750 kg, plus a 350 kg load capacity.
The rear axle - the available space seems to dictate that a compact drive unit be used, since otherwise my battery space would be cut down the middle.

To give a good idea of the space requirements, here are the general dimensions:

Goals:

Must-haves

• Heating and cooling - won’t get driven without it. My last 'fun' car sat idle eight months of the year because of this.

• 55 km of range (a round trip to where we dispose of our household waste)

Strong wants

• No ICE transmission/driveline

• 150 km range (a round trip to The Big City)

• High voltage (400 V, not 48 - 125)

Nice to haves

• No visible screens

• No noisy and superfluous vacuum pump

• CCS

I would like to use 3D scanning and CAD to reduce the downtime as much as possible, since I do use the truck fairly regularly.

[bexander]

Love those tiny trucks!
How about a Nissan Leaf motor connected directly to the propshaft. I belive the rear axle is approx 5:1 and the motor produces about the same torque as stock ICE in first gear. You can alwas limit max power.

[maboyce]

I know that converting RWD vehicles with solid axles can be a challenge, and this one is more so than usual.

I looked into chopping the solid axle and adding a second set of bearings to hold a custom stub shaft, but the CV axles would have been absurdly short.

A custom De Dion axle would work, but few available off-the-shelf parts would be helpful. The stock wheels are 12" and take 180 mm drums with a 4 x 110 pattern, plus a 67 mm centring spigot. Some ATVs use 4 x 110, but their brakes are all too big or are motorcycle brakes. VW parts are common, but again the brake discs are enormous and the pattern is wrong.

Happily for me, the Honda Acty has a De Dion axle from factory:

The big compromise is that the Acty has a 4 x 100 pattern rather than 4 x 110, so I would have to use an adapter or have different wheels front and rear. All kei trucks of this vintage have pretty similar 12" steel wheels, so I think I can live with that to get me on the road. In a pinch there are actually dual-pattern wheels sold in Japan that I could use.

I still need to get measurements on the Acty axle (I assume the spring width is 'close enough', but I haven't been able to find out online), so this may end up not being a viable solution after all. If not, I do have measurements of the existing brake drum and splines and could make/hire a custom axle if I were really determined.

The Acty has the rear wheels a lot closer to the end of the bed than this truck, so I think I can flip the axle and put the drive unit behind the wheels where the spare tire and fuel tank used to be. A Leaf drive unit seems to fit nicely and leave space to the side where the charger and other electrical boxes can go (I haven't found a way to save the spare tire; please ignore it):

For context, here are 5 Mercedes EQS modules as a battery pack (I think daveturpin here is using them):

[maboyce]

Love those tiny trucks!
How about a Nissan Leaf motor connected directly to the propshaft. I belive the rear axle is approx 5:1 and the motor produces about the same torque as stock ICE in first gear. You can alwas limit max power.

You know, I didn't really consider this, but it does actually seem to be viable. Here are the stock drive ratios with the engine specs again:

32 kW @ 5,900 RPM; 59 Nm @ 4,400 RPM
Stock transmission ratios: 2.8, 1.54, 1.0
Stock rear end ratio: 6.666

I've been using the 'EVDesigner' spreadsheet that was shared on here a while back (thank you to jetpax). Here is what it thinks of the Leaf motor with direct drive (ratio 8.193):

And with the stock rear end through a driveshaft:

If anything, the latter gets a higher top end speed for a tiny acceleration penalty. The challenge would be weight and packaging, as well as the custom driveshaft. This truck actually has selectable 4WD, so I will eventually need to have room for a front motor as well unless I want to reuse the stock transfer case somehow. All of that takes up my limited battery space.

[Bratitude]

why not an outlander rear drive unit? slightly better gearing than the gearbox leaf for your smaller wheels, lighter weight and you wont need to run it backwards.

[maboyce]

why not an outlander rear drive unit? slightly better gearing than the gearbox leaf for your smaller wheels, lighter weight and you wont need to run it backwards.

It was actually my first choice, even though I would probably have to import one from overseas. I moved away from it because Leafs are much more common (It looks like I can get a first-gen parts Leaf for about the same price as an Outlander drive unit) and have a parking pawl. It looks like most EV conversions just don't have a meaningful 'park' position, and even production EVs seem to use their electric parking brake for 'park'? I'd like to keep the stock shifter working as expected if possible, instead of having 'Park' be another 'Neutral' or something like that.

I'm very open to other small drive unit alternatives. The Toyota MGR is still in the running for the future front 4WD motor. I looked into some of the other Toyota E-Four motors and the Nissan Sakura MM48 drive unit, but they all seemed to have issues with voltage, size, cooling, or in the case of the latter, an integrated inverter that isn't hacked.

Bratitude, while I have you, do your Leaf-930 CV axle adapters work in the EM61 as well as in the EM57? The listing only mentions the latter.

[Bratitude]

where are you located? in the us? outlander stuff is in the us now, and has been in canada for a bit. with some hunting you can find it for cheap!

im not sure what you problem with parking brake is. how the oems create the user interface dose not matter here.

is the shifter an auto shifter with a p position? if thats the case just use that to trigger the parking e brake....

dont have stubs for the em61 unfortunately. they are smaller than the em57 ones. why not just use the leaf cv joints and wheel bearings?

[bexander]

The outlander rear motor is alot smaler than the leaf and would still provide more torque than stock motor/gearbox (59*2,8). Connect it directly to transfere case an retain hi/low gear. How much room for batteries would there be left then?

[maboyce]

where are you located? in the us? outlander stuff is in the us now, and has been in canada for a bit. with some hunting you can find it for cheap!

im not sure what you problem with parking brake is. how the oems create the user interface dose not matter here.

is the shifter an auto shifter with a p position? if thats the case just use that to trigger the parking e brake....

dont have stubs for the em61 unfortunately. they are smaller than the em57 ones. why not just use the leaf cv joints and wheel bearings?

Yes, the US (probably not that far from you if you're on Vancouver Island). I've seen a few in-country ones on eBay, but the cheapest ones were from the UK the last time I looked.

I'm working with an auto shifter and a manual parking brake, and I'd really like to keep both of those things as-is if possible. I love the look and function of the interior and I'd like to keep it as-is as much as I can.

As for the axle stubs, I was just exploring the solution space. EM61 cars are half the price or less compared to any later Leafs around here.

[Bratitude]

outlander stuff in north America is not well documented online. but they are in yards. ebay is always 2-4x the price...but sometimes your lucky.

outlander seems like a good fit size/gearing/ power. i will be picking up a bunch of outlander drive units, ill see what price comes out to be

some one on the forum has used the leaf parking prawl with a manual shifter. they just made a linkage that mounts to the leaf box. its just a shaft you need to rotate, so no problem there. but why not just use a caliper with an ebrake cable attachment?

shifter would just require putting micro switches. likely already has them for the dash lights anyways

[maboyce]

The outlander rear motor is alot smaler than the leaf and would still provide more torque than stock motor/gearbox (59*2,8). Connect it directly to transfere case an retain hi/low gear. How much room for batteries would there be left then?

It should be technically possible, but it does look a little tight. The transfer is a 1:1 chain drive unit. Apologies for the poor diagram, but the underbody scan took 18 hours to process and I did it after deleting the ICE drivetrain from the point cloud!