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jonescg's eCRX pre-build thread!

Hey Kurt, nice looking sliders on that beast! Looks beautiful.

I really wish I could just shove a naturally aspirated inlet on the engine, but since it's currently unregistered I don't want to be doing any modifications that mightn't be approved. I think the rule here is, if it came with EFI and emissions controls in 1988, it must be maintained to the 1988 standard. I wouldn't be able to 'send it backwards' with carbies. Hopefully it won't be an engineless wreck in the drive way for 3 years...

I took it to Daniel's shop in Balcatta to get the EFI looked at. It's running terribly; misfires, low power, rough idle, runs rich and fouls the plugs, and needless to say, lousy fuel economy. I have replaced the faulty throttle position sensor and put new spark plugs in, as well as returned the OEM air box and filter. At least if it can't be saved, EV Shop is just on the other side of the workshop :lol:
A common issue was the valve cover weeping oil that ends up at the lowest point (holes for spark plugs) Doesn't take long then before your ignition leads are cooked - toast and then the coil.

If you haven't changed them already its a good $60 investment that might be the answer to your sluggish motor.

Yep - that's the one. Good idea - I will look into new leads and overhaul the system. And get a new rocker cover gasket...
Not much to update on the electric side of things, but Sturt the CRX is now legally on the road!

I replaced the ignition leads at the same time I replaced the rocker cover seal and spark plug grommets. Made a world of difference. I also finished welding up the battery cage and holder. Four new boots and a wash and she was looking good. The broken headlight was replaced with an eBay headlight and after searching around for the right bulbs, seems to be holding up OK for now. I will eventually replace them with some plastic LED powered headlights.

Looking at the space available, I might just rip the fuel tank out and put all of the batteries in the back behind the seat. It won't eat into the boot space all that much, but I can actually move the spare tyre to under the hood. The spare tyre well can provide extra storage space should you need it.

37 kWh of these EIG cells occupies a space about 800 mm wide and 600 mm deep, and 240 mm high. This will fit just in front of the rear wheels so handling shouldn't be compromised. Moreover, I can access all of the cells without a hoist. That is worth it right there! I'm going to be pushing the GVM to its limit, since I can only salvage about 200 kg from the old ICE system, and these cells will weigh in at about 220 kg. Still, it currently has a tare weight of 895 kg :D

Lots of EV guys keen to go in on a group buy, so maybe in the next 6 months (depending on this year's Voltron build) I might make an order. Better get these cell terminations sorted out.
Today I went and bought a hydraulic jack and decided to change the oil in the car. Holy shit, was this a gong-show. The CRX was already pretty low to the ground, and the previous owner had it lowered further still. So I had to jack it up in several stages before I could put the supports under and proceed to do the dirty deeds. Well the catch tray leaked, the filter was stuck on firmly so I had to bush-mechanic it off (drive a screw-driver through it and twist) which covered me in more oil... But I finally did the oil change.

All of this has re-affirmed my desire to electrify the CRX. Oil changes are a pain in the arse, the fuel economy is so bad that an F250 looks good in comparison, and the weird vibes at 2100 rpm are off-putting.

So I decided to do some measurements.


A 37 kWh pack of EIG cells is 168s3p. I can make this as 6 blocks of 28s, which once isolated, is in the realm of ELV segments. 6 rows of 84 cells measures in at 605 mm deep and 780 mm wide. I will be separating them with 5 dividers, so lets call it 822 mm wide all up. The height of the cells will average about 240 mm, but will be higher at the back to accommodate the contactors and fuses etc.

Battery location.jpg

This is ideal, as the weight is still in front of the rear wheels. It's pretty substantial (230 kg) so I will be cutting into the chassis and reinforcing with plenty of steel brackets. It also leaves the front pretty light - just a 40 kg motor, 11 kg controller, a small radiator or two for the motor and controller and a couple of 350 V chargers. Just as well as I plan on getting rid of the power steering. I'll keep the heater box as it runs off the 12 V system, and hopefully won't get used that much.

Assuming an average economy of 150 Wh/km, which is probably pretty good going, I can get 250 km on a charge. Not much less than what I can get on a tank of petrol!! I heard that an iMiEV can get 140-160 Wh/km, which is impressive for a car shaped like a brick. Imagine what a CdA of 5.2 will get!

I have to keep reminding myself I have to build a race bike first...
my crx does not have that big boot in the rear. goes flush to the rear of the car inside, and there is a pan in the body in front of the rear axle below where you have outlined your battery box.

i would recommend removing the upholstered part and go find the sheet metal underneath. they use the little plastic captive screw/plug and regular phillips head screws.

my hondas are smooth as butter. amazing it would be so much outa balance. mine are smooth up to 5k rpm.
You should figure out the fuel economy thing. It maybe pumping to much fuel into the motor and this will ruin your new oil fast. If you have a miss at 2100 rpm maybe its a cylinder not running right or at all at that rpm which could be a lot of things but the unburnt fuel will just seep down the cylinder walls and mix into your oil.
250kg isn't that bad considering the capacity of the pack. remember you usually have 40kg of fuel and another 10kg for the tank its self and pump in that position. So considering the civic is basically the same chassis and can have three adults in the back sitting over the rear axle at say 75kg each. That's 225kg + 50kg mentioned above and your at 275kg.

What about splitting the pack in two and balancing the weight?

Doing away with the jack spare wheel can save you some weight. That if your packs 250kg and your only adding 100kg or so more for the motor, controller charger I don't see 350kg being a big issue spread out in a two seat car that's been stripped of all its ICE running gear.

regarding the rough honda motor. I too get the feeling something is seriously wrong. The 80's honda motors where balanced extremely well and you should be able to get 600 - 650km out of that tank on the motorway.

Kurt said:
250kg is'nt that bad considering the capacity of the pack...

I assume that's what you meant to say? If the GVM for this model was about 1200 kg, I should be OK. It's current tare is officially 895 kg. If you add 2 x 85 kg for occupants, and 45 kg for luggage, we're at 1110 kg. I can't find any reliable literature on the GVM of the CRX, but depending on the model it ranges from 1140 to 1300 kg :?

So taking 896 kg and removing 200 kg worth of radiator, exhaust, fuel tank, fuel, pump, power steering, clutch, engine and ECU, I am down to 695 kg. Put 40 kg worth of Evo motor, 12 kg worth of Rineheart controller, 10 kg worth of adapter plate and 10 kg worth of switch gear and wire, I am back up to 767 kg. Throw in 250 kg worth of battery and we're at 1017 kg kerb weight. I might be overestimating my added weights, and underestimating the removable weights, but exceeding the original GVM by 100 kg is likely.

I'd rather not split the pack for simplicity, and because I can't find a usefully big enough place to put the other half. 250 kg is within the realm of most workshop hoists, and given it's location I should be able to disconnect the pack with a pair of gigantic Andersons, undo 8 bolts and hoist the lot out the back hatch in one go. The pack will have a polycarbonate cover so you can see any problems arising, and I think I will have a little exhaust fan which helps keep things cool during charge and discharge - maybe duct it from the front and blow it out the back or something... I also hope to use plastic to build the pack, rather than aluminium like so many others do. With voltages this high, I would prefer it if everything was as non-conductive as possible!

As for the petrol motor, it's got me stuffed what's going wrong. I could replace the coil in the distributor since this might have been damaged when the leads were shorting. Plenty of unburned fuel going through the tailpipe :(

Hope I got a job next year, cause between this project and the race bike, it's all pretty exciting :)
jonescg said:
As for the petrol motor, it's got me stuffed what's going wrong. I could replace the coil in the distributor since this might have been damaged when the leads were shorting. Plenty of unburned fuel going through the tailpipe :(
The distributors are a common place to look for issues. I usually replace the distributor as a whole to see if it will make it run. I have replaced a few components inside them as well but I find its faster to replace the whole distributor.
jonescg said:
The CRX was already pretty low to the ground, and the previous owner had it lowered further still. So I had to jack it up in several stages before I could put the supports under and proceed to do the dirty deeds.

Drive the car onto blocks to raise the front enough to slip the jack under. Easy ;)
Punx0r said:
jonescg said:
The CRX was already pretty low to the ground, and the previous owner had it lowered further still. So I had to jack it up in several stages before I could put the supports under and proceed to do the dirty deeds.

Drive the car onto blocks to raise the front enough to slip the jack under. Easy ;)

Ya ya ya... :)
The spare tire in front makes a good crash cushion. I found out the hard way in a Renault Gordini which had the spare laying horizontal in a tunnel between the front wheels. I T Boned a red light runner and the spare was bent into a C shape.
Hi folks,

I just had a thought about the drive train in my CRX. Mounting the motor to the gearbox seems wasteful, but getting a 44 mm shaft to fit onto a 19 mm shaft and having it clear the half shaft won't be easy either. So how about taking an independent rear suspension diff from another vehicle and using this to drive the shafts? I could even mount the motor behind the diff but in front of the firewall so as to keep the weight between the wheels.

Does anyone know of projects that have done this? Any Diff with a ratio of about 3.8 to 4.0 : 1 would be ideal.
you could look in the junkyards for a honda rear independent suspension, they have had a series of 4WD since the early 90's so maybe they would be the best place to start. also subaru, but you wanna have the inner part of the CRX axle so you can see if it will fit into the splines and the circlip is in the right spot to hold the axle in place, and the oil seals too. but you know this already.

i just was thinking honda 4WD might be the best one to check since they may have used compatible dimensions and splines.
I had a quick look at CRV diffs, but the front diffs are all transaxle, and the rear diffs are actually quite long, and I'd probably be hitting the firewall with the back of the motor. Provided any other IRS diff can be run upside down, or alternatively, run backwards, it might work. I'd just need to come up with a serious mount for the diff-motor unit.
long makes sense because they are using the housing for the torque arm. maybe the guys to ask would be in a transmission shop. they will have a good idea of which might be most adaptable.

thinking some more about the splines. you may/will be forced to make a hybrid joint at the rizeppo. use the inner part that goes to the differential and then the rizeppo part with the three pronged part with the rollers that go inside the rizeppo from the same as the differential and then your axle shaft from the CRX would have to be machined to insert into the tripod part.

you will have to machine the half axle to length anyway so this could be done at the same time. they could machine the end of the half axle to fit inside the tripod of the rizeppo that goes with that differential. machined to include the circlip that holds it, and the splines to match. or they could be cut off the old half axle and welded to your CRX half axle.
I'm seeking more information from an EV enthusiast in Cairns (FNQ) who put one of these big DC motors into his Proton:
Interesting - Kim said he used a Rav4 diff. It was the easiest to make it fit of the Diffs available, but was quite tall at 2.9:1. CRV diffs, being Hondas, might fit my front drive shafts better, but they are a 4.43:1 diff, giving me barely 110 km/h at top speed. Maybe a Subaru WRX IRD diff would be ideal? Or a Nissan Skyline IRS diff? They seem to be in the 3.8-4:1 range. I think 3:1 would be a bit too tall.
after thinking about this, it seems inevitable that you will have to cut the CRX half axles in any case in order to make them the right length when the differential is installed.

this means you can use the rizeppa components that go with the differential and then weld the cut CRX half axle to the stub left on the half axle to the differential that also would be cut so that the two when welded together will get you to the specific length needed to make it work.

so my original thought that you need to worry about the splines and circlip are irrelevant now. just finding the differential that will fit the space will be a big enuff task.

even if you have a big junkyard to go through looking at the rear differentials, all the vehicles are still intact so you would have to climb under each vehicle to make the measurements. this is not something most of us would take lightly. seems like the junked cars are perched precariously on old rims. without protection it is hard to climb underneath them to measure.

but i think you are on the right track. i had thought about using the tailshaft that goes out into the covering over the 5th gear pod on the upper outside of the tranny on the CRX. my idea was to make a hybrid by adding the drive motor there so it could be coupled to the tranny through the fifth gear, but that involved having to use the tranny while the gas motor was disconnected by holding down the clutch to keep it disengaged.
I'm thinking a Mazda MX5 NB series (aka Miata) IRS diff would be ideal. They are about a 3.6-4.1 ratio, giving top speeds of ~160 km/h and ~130 km/h respectively. Best of all they have a really short pinion section and come with nice wide mounting struts.


It gives me plenty of room either side nearest the firewall for stuff like controllers, chargers, contactor boxes etc. I still plan on having a one-piece battery in the back though.
Wow! An update!

My mum and dad have dropped in to hot old Perth for a Christmas/New Year visit, and they gifted me a metal cut-off wheel! Now I can cut steel at 45 degrees without guessing! I decided to try it out and weld up a rectangle the same dimensions as the battery destined for the CRX:

battery tray CRX.jpg

Battery tray in position.jpg

This fits between the main suspension support and the front of the petrol tank. It will be sunken into the body about 200 mm, so the weight is as low as practical. I was surprised how small it will be. 37 kWh should get me 200 km at 100 km/h, or possibly further. I also learned that a Toyota Soarer has a Diff of the ideal ratio and size, so I shall keep my eyes open.

Back to the job hunt!
I saw driveshafts mentioned above. Don't worry about mating the original shafts to an alien gearbox or diff. It's fairly trivial to the two odd sets of shafts cut, welded and balanced to mate the new parts. It's common practice when making ICE-to-ICE engine conversions.
Holy shitcakes an update on the e-CRX!

I have designed some boards for the EIG cells. I got Full-Throttle to knock them up as Gerbers and I got a factory in China to make three of them to see how they look.

All up I'm fairly impressed. Basically I can mount three of the 20 Ah cells in parallel and the links make the final connection in series. These 150 mm long and 130 mm wide boards will hold 21 cells, or 1.5 kWh. The traces are not good for much current - maybe 40 A at the absolute most, but they are really only there for show. I will be using a piece of copper to clamp the tabs down and continue the diagonal link to the next cell in series. These are tightened down with stainless steel M3 screws into brass nuts which are soldered to the back of the board.

Even 1.6 mm thick copper plate would do the job - I can't see me exceeding 200 A very often - at 640 V that's still a legit 128 kW from the battery - enough to overtake a Ferarri in my 1100 kg CRX? We'll see :)

I also got some 21s 1p boards made up for the EIG cells, but I'm not happy with them. There is too much potential to short them as they don't have the luxury of a 7 mm gap between cells. More like 0.6 mm :evil: They will need some more thought.
And I'm FINALLY in a position to start planning the conversion...

I was about to start a thread asking about Nissan Leaf motors, but then I remembered I have an unfinished build thread here :oops: .

So what's happened since the last post? Well I moved house three times, even moved to a different city for a good 18 months and came back. Changed jobs a few more times and finally settled back in Perth. We bought a house in Kalamunda (Perth hills) and it has the most awesome workshop. This is all part of my plan to convert the CRX - I need a decent workshop with a hoist to make the job easier. I also need to make sure we're covered for vehicular transport while the car is off the road. And also, I have another car to convert between now and Christmas (!) although that job is well underway and should be starting very soon.

In this picture, I'm standing where the hoist will go.

My reason for dredging threads from the dead was to ask about Nissan Leaf motors and inverters - specifically, are they able to be run by simply powering them up? Or is it expecting a signal from the Leaf VCU before firing up?

I was initially happy to just remove the inverter from the Leaf motor and use a Rinehart PM150DXR but if the inverters work OK out of the box, I might put the inverter off till later. Particularly since I can't afford to throw too much money at this (budgeting AU$40,000).

Any experience out there?