I thought I would start a post to document the conversion of my 90 Si from a non starting craigslist buy to a restomoded EV. I started this all around 6 months ago. And will slowly bring this up to speed.

The Donor
I had been looking for a project to keep me occupied in my downtime. Growing up I loved the CRX but for reasons beyond me my mom wouldn't let me buy one but was fine with me getting a 98 Accord Coupe V6 as a first car. 15 years removed it felt like the right time to finally get the car I dreamed of as a young teen. Craigslist wasn't turning up much. $3000 dollar rust buckets I would have to travel to buy. I lucked out finding the car I did. It didn't run but was only $1000 dollars and rust free (for an 90 civic in BC at least). All I knew is it fit the bill. I went to the bank and bought it that day. This is it arriving in the driveway last September.

Previous owner said the one before him repainted it. The dad and daughter did a backyard respray. Having sanded back some layers they put new primer, base, and clear on top of the original paint job. I think it honestly helped protect the car even if there are runs everywhere.


Backed into something at some point

To say the paint is rough is an understatement.



The only rust to be seen. Couple bubbles on the rear fender and some under the gas door.




The Plan
A restomod requires ambition in my mind. So after some pondering on what exactly to do my vision slowly became clear. It didn't hurt that I love my girlfriends EV. The CRX would be converted to RWD EV. Comforts like power steering, AC, power mirrors, non vaccum reliant brakes. All quickly got added to the list. Along with stripping the car down and giving it some fresh paint. Being further on than just this post I have the advantage of knowing I managed to sort most these things out with a little help from others online.


I will try to post daily until I am caught up with present day.

 

So I started off slowly peeling back the cars layers. Removal of the rear interior gave great access and vision of how bad the rust actually was. And considering the cars life I was pretty pleased with this being the extend of body rust on the car.







Unfortunately this car like too many had owners who ignored chapters of their owners manuals The sunroof not only didn't move it was completely siezed. This quickly became the first Item I tackled. Removing the actual sunroof was a good deal of work but I did manage to get it off. Inspecting the tray showed its drains had become plugged and nobody ever applied any grease the cable drive tubes were siezed solid with rust and grime.

The sunroof was in rough shape too. After sanding through the 6 layers of paint and getting a better appreciation for its condition I bit the bullet and ordered a fiberglass replacement


The photos don't do the rainmaker sounds justice.


As far as the sunroof mechanism went only one plastic piece was broken.




To repair it I opened up the mechanism Drilled two tiny pilot holes. I then took some fine machinist wire and laced it back to the original piece before coating it all in plastic weld.

Fixing the cable drive was a little more difficult. Upon disassembling the motor and tubes the problem was quite apparent. The motor itself ran fine however the cable drive was nearly a write off.




To fix it I used some vice grips and slowly dripped in WD-40. A couple drops every 10 minutes for hours. I then took a map gas torch to the tubes cooked them nice and hot. Then grabbed the ends of the cables twisting and pulling until they broke free. Once they had it became a cycle. Clean.... Grease... Work back and forth... Clean... Grease.... work back and forth. until they were moving smoothly.






With the tubes clean and moving I sandblasted the tray and gave it three coats of fresh paint before reassembling on the living room table. Happy to say it was all a success.
All told about 1 weeks work just on the sunroof but well worth it. Since crusty old ones sell for 500 dollars on ebay.

 

So what EV drivetrain?

​​​​​​Zero motorcycle conversion?

EV West kit?

Rwd maybe?

 

I am going with the small rear unit out of a Tesla Model S. Converting the CRX to RWD with the batteries living in the engine bay.

While some of the package options are nice they give up a lot of what I am going for with the build as far as integration and feature sets. There is going to be a good deal of custom programming behind the skin of the car when it was done.

Also fun note even as a mechanical engineer this is how I made sure I could make the drive fit.


Also who in their right mind puts 88-89 rear lights onto a 90. Literally had to go out of their way to make the car objectively worse looking. This will be fixed.


Nothing beats a nice physical mock up.

Here is the actual drive unit.



I just have to do some machining to allow me to run it upside down. There will be more on that in the future. But I don't want to get ahead of my story.

 

Neat.

S2000 or Miata suspension?

One of those is the wrong answer.

 

Reenforcing the stock points and using a AWD trailing arm kit. Once I have the final weights I am going to get some custom coilovers. But I don't see the need for reworking the suspension geometry.

 

youre going to power all the torque from an electric motor to the OEM realtime rear drivetrain?

hmmm.... have you seen how little torque those spindly rear axles were designed for?

i dunno, is there an example of this done and used before?

i think its a great opportunity to modify the front and rear suspension points actually. but these are just my own wishful thinking perhaps.

 

From the looks of it, he's going to adapt axles from the tesla transmission directly to the trailing arms.

It will be a mid-engine EV. I don't see why he'd need the rear diff from a rt4wd setup.

OP, looks great. I love custom builds like this.

 

Thanks and yes using custom axels right from the drive unit.

The drive unit is its own motor and diff. And the countless 500-1000 hp awd drag builds using what is effectively stock suspension would suggest it is more than strong enough. Especially when the vehicle weight is take into account.

Suspension and suspension geometry is not something to play around with. I cringe every time I see the things some do thinking they know better than teams of engineers.

 

tbh i really dont know if ppl used the oem trailing arms for high torque applications. but i can safely assume a "team of engineers" didnt expect the instant torque of an EV drive thru the wagon suspension.

but if its been precedent with high hp dragsters to last, then great... thats why i asked.

and as a mechanical engineer myself, i would love to sink my teeth into redesigning the suspension geometry for my specific application and ride height, roll centers and performance. but seems like you got enough on your hands.

 

Yes i could redesign everything but considering very little is actually changing. It is worth neither the time nor money. The small drive unit is a 220kw model peak torque is around 250ft.lbs. A turbo K series makes those numbers all day.

All said I am not modifying any suspension geometry because there is no need and for minimum benefit on what is already a great handling vehicle.

 

One of the earlier decisions I had to make surrounding the swap was maintaining ancillaries such as power brakes. While some would say they or power steering are not necessary my personal feelings on the matter were that I would much prefer to have them than wind up wishing I had gone with them.

Brakes.

A good deal of work has gone into hacking tesla parts for use in other EV's with people having quickly learned the Model S Electric brake booster operates in an independent mode when not receiving any can communication. I decided to go down this path vs the other common route of using a vacuum pump and reservoir in conjunction with the stock brake booster. Sadly this meant that people were after the tesla I-booster which is manufactured by bosch. What people haven't caught on to is just how many vehicles use the exact same part. Mine came out of a 2018 CR-V (Had to keep it in the family) The benefit was a brake booster that cost me $100 dollar vs the $500 plus countless people ask for a tesla part.


Best part is even though it is from a honda it still had the tsla part number from bosch.


Now betting that a part from a vehicle nearly 30 years newer would just bolt in was a long stretch but at least the fabrication would be pretty simple....

OH WAIT



Quite literally bolted straight in. Was shocked the bolt spacing never changed over the years. The stock hole was a hair tight for the newer part but literally knocking the paint of with sand paper was enough to let it fit. Stock brake lines match up with relative ease and making a tiny reservoir bracket won't take long at all.


Also yes the engine is still in. Broke two breaker bars a 1/2 inch and 3/4 inch drive trying to get the axle nuts off. So I just felt like putting it off while I do other work on the car.

 

Very cool man, I'll be following along closely as I've been wanting to make my 83 Civic an EV.

 

Awesome, definitely following this one along.

 

With a plan in order for the brakes next was the steering.

Now some may question my decision to go this route but I am going with Electric Power Steering. I made this decision for a couple reasons.
1. No changes to the stock rack or its mounts.
2. As much or as little assist as I desire.

A quick google on the matter will find countless "kits" to do this for various vehicles. They all boil down to one basic fact. Almost every electric power steering system out there has a standalone mode. Given power and no signal from an ecu it will go to a default assist. Some kits use a box to generate a PWM wave to simulate a speed signal and use a potentiometer to adjust that. I intend to actually simulate the correct signals, or at least the ones I want the steering rack to see.

This is the rack I settled on.

Banana for scale

It came out of a 2015 Nissan Versa. There are a handful of standard choices for somebody doing a conversion but most boil down to one thing. The EPS being made by JTEKT, They are one of the biggest and are plentiful.
The main reason I chose this over the Saturn Vue, Toyota Yaris and many other common options is pretty simple. I know somebody with a 2015 nissan versa which means I can plug in my trusty can sniffer and gather the correct messages to operate the rack. The second is the Nissan versions of this power assist have a detachable brain box which will let me relocate it to a more convenient location. Interestingly one of the hardest parts so far to this was just identifying the part number to the power plug it uses since I did not receive it with the part.

I will more than likely use far less assist than would be standard but ultimate with the vehicles weight increasing some I felt this would be an easy modification to make. Unlike the brakes this is gonna require some fab to fit under the dash but I am confident I can find the room.
Much of the work that kept me busy through the fall was carefully stripping the car down back to its shell. Gas tank was easy since I cared little for its connections. But some other bits were hours of careful labeling and documenting so nothing would go missing.

 

Last week right before I saw this i was thinking in my head. Why can’t I put a beefed up Brushless motor In place of the starter. Something that would take it to at least 12 or 15 mph then with also a more beefy battery you just made a hybrid for maybe $1000 including everything

 

I think your going into the wall with a rwd Crx with snap torque and a go kart wheel base lol make it fwd man Don’t you think it’s more likely to go where you steer it with fwd

 

There are several companies that have tried to come to market with similar products. But most never caught on due to cost.

As far as "into the wall"
1. I have complete control over the power curve via ecu. I decide how snappy that torque is and can very easily inplement traction control.

2. From talking with two others who have done rwd crx conversions albeit turbo f20 ones they handle spectacularly.

3. The Crx and s2000 are surprisingly close in wheelbase and trackwidth. And while yes the differences exist. Suspension design being on. Crx 2300mm wheelbase 1450mm track width. S2k 2400mm w.b 1470mm track.

It is hardly scientific but enough for me to believe I am not gonna Mustang when I put my foot down.

 

Im so pumped to see this build come together! Hell yeah man!

 

I'd love to build an EV someday too, this thread is exciting! can't wait to see how this engineering comes together.

 

You would be safer being generous with your torque if it was fwd. almost anything set up MR is going to handle like a Porsche and a Porsche handles like a Porsche. So I’m not saying what your doing is not a bad idea. TBH I hope your badass project gets gutted/roll caged with fat slicks and doesn’t turn into a street track de tuned to tenth power resto mod

 

This will be awesome

 

I'm assuming you've seen the billet awd rear trailing arms, right? There's not really any oem wagon parts on these new AWD setups... Except the rear diff, which isn't present in this particular swap

 

billet awd rear trailing arms

no, im not aware. that makes sense. is OP planning to use those? sounded like he was just bolting up stock suspension because it was designed by a team of engineers.

but then again, if i was going to buy/make/fabricate some new trailing arms, why would i just keep the stock design meant for FF? just seems silly to me, i'd start with an s2000 stock setup and adjust roll center and heights.

its not like the LCA are even going to be mounting to the same spot either... shrug, not my build.

 

I have seen most of the various versions of arms. I haven't seen any billet arms. I know s1built makes cast aluminum arms with a modified toe setup. I am going with boxed in ones as I am confident for the power and loads they will suffice.

for reference these are the cast arms S1 Makes.



Tyson don't mistake stock geometry and mounting points for stock parts. None of the driveline come from anything honda. I have seen your thread on trying to fit s2k suspension into other cars. If that is what you wish to do all the power to you, but it isn't what I am doing. So it would be nice if you stopped trying to push that point.