bawfuls

No one can provide you with an all-in weight because it varies significantly depending on batteries, but here are some numbers for a bit of context. My Z uses a smaller motor which provides roughly equivalent power (but more torque) to the stock L28 and weighs 120 lbs. I used 5 Tesla Model S battery modules (less than half a full pack) which are excellent from an energy density standpoint (275lbs for 26kWh not including the battery enclosure). My car in total is 2450 lbs without driver, so I did actually drop some weight vs the stock setup. I have a long spreadsheet comparing various potential battery modules for EV projects, and their weight varies substantially, from 10-30 lbs/kWh. The batteries I have are on the very low end of that range, but they only get me to a nominal 114V which is fine for the motor I have but wouldn't be suitable for a Tesla motor (needs 355V). The higher power upgrade I've been looking at (swapping to a small Tesla motor for ~300hp/250 ft.lbs) would likely add some weight. The motor would be 200lbs instead of 120, though I'd drop the transmission, bell housing adapter, drive shaft, and differential while adding a new rear subframe to accommodate the motor. Batteries would be ~500lbs before enclosure so nearly double what I've got now, and I'd need a real radiator. I would guess it ends up a couple hundred pounds heavier, which imo is a fine tradeoff for the additional power. The batteries are where most of the weight is in an EV conversion. Motor+inverter is next, but after that there is very little of significant mass. Volt batteries btw are some of the heaviest (~28 lbs/kWh) and bulkiest, but they are the cheapest way to get a high voltage pack and they've got nice integrated cooling. A full Volt pack is 400lbs, 360V nominal, but only 14-17kWh. The guy who put a large Tesla motor in an E30 (@tesla_bimmer on IG) has two full Volt packs in parallel in it, they occupy the whole engine bay and trunk.

I did a thread on another forum which you can read there, but not on HybridZ. The Tesla motors all have a single speed reduction gear (in the case of the small rear unit it's 9.34:1) so you select reverse by running the motor the other direction. The engine bay of the Z is pretty roomy for how small the car is, but you still have to select batteries carefully to get what you need into that space. I'm kicking myself for not paying attention to this forum a couple years ago when the most recent 3D scan and CAD of the S30 was kicking around, it would be extremely useful for planning this build.

Did you ever make progress on this? If so I'd love to see how you did it. I did an EV conversion on an s30, but used a smaller motor which I mated to the stock transmission thus leaving the stock rear end unaltered. It was my first car project so I wanted to keep fabrication simple at the time. I'm thinking about upgrading though, and re-doing the car with different batteries and a small Tesla rear motor. Here's a mock up illustrating the fitment difficulty: Another issue is vertical clearance, in order to avoid interference between the control arms and the motor, the motor will need to be high enough that it'll require some cutting of the trunk floor above it I believe. The distance from the underside of the trunk deck to the top of the control arm inboard mount is ~7.5 inches, while the small tesla motor requires about 10-11 inches of vertical space.

Spent a couple hours on this again today for the first time in awhile, because this week the headlights stopped working all together, even on the high setting. I verified continuity on the ground side of things (headlight sub-harness to the white C-9 six-pin connector, from there to the combo switch, etc). Now I'm getting a symptom I saw previously (I think, maybe 8 months ago, hard to remember), which is full battery voltage (13.6V with the car on) at the middle (fatter) connection on the headlight sub-harness when the headlight switch is on the HIGH position (no voltage when off or LOW). From my reading of the wiring diagram, this pin should be the GROUND for the high beam position. This is very confusing! This pin is wired directly to the white C-9 six-pin connector on the passenger floor area, and I've verified ground continuity at that point.

Perhaps I will eventually, but the 5 battery modules I've got in it now were 40% of my total project budget. And with the voltage range of the motor I've got, I can't just add one or two, I'd have to add another 5 in parallel. So for the time being, this is it. I could have designed it originally to split the pack, with say 3 in the rear and 2 up front, but for simplicity I decided against that.

Update: flywheel measured at 0.4 grams out of balance, i.e. just fine. Reinstalled everything this afternoon an behavior is as before. So, if it's not the flywheel, and it's not the transmission, best guess is it's the alignment of the motor and trans shafts (as has been suggested). I need to head over to the EV speed shop this Wednesday anyway to corner weigh the car so I'll pick their brains about it then.

I was out of town all last week so I'll have to go pick up the flywheel today and see what they say. Will update this afternoon or evening.

I took the flywheel assembly back to the shop to have them re-check it's balance. They will take pics/video of the readout for me, and if it's still balanced I'll owe them $45, which seems worth it for the piece of mind that the flywheel assembly is NOT the issue. If this comes back balanced I am really out of ideas here.

Alright so I just did this, outside in an empty parking lot, with the handbrake on and the transmission in 5th gear. Car did not lurch at all, and there was no burning clutch smell, so the clutch appears to be disengaging properly. The vibration was still there at higher RPM just as before. Sure is starting to feel like it's still the flywheel/pressure plate assembly after all, as you suggested. Should I take them back to the same shop and have it re-checked? They will surely do it for free, since they are the ones who potentially screwed up. Or should I take it to a new shop, to get their worked independently checked? edit: I just pulled the motor, about 2 hours after doing this test and then parking the car and plugging it in. The motor is warm to the touch, which is odd. Car has been parked inside a garage with ambient temp ~60F for two hours. Charging shouldn't warm the motor either. Perhaps the clutch wasn't disengaging so well after all...

That alignment is determined by the location of the holes machined into the red adapter plate. So I am relying on the company I order that from to have done their job properly. They sell these kits for a wide variety of cars, and there’s an EV conversion shop up in NorCal with a YouTube channel (EV4U) who recently used their kit for a 1978 Z without issue, but it’s certainly possible mine is misaligned slightly. I should have (but did not) verified the alignment with a laser or string when I first got it and test fit: Today I will try the test NewZed posted in bold and report back.

Yeah I could go back to the shop that balanced the pressure plate and have them check it again. I guess I could request they put it on the machine while I watch and see the results? I agree though, it does seem odd that a brand new in-stock-at-AutoZone pressure plate would need that much modification to balance. The other reason I'm skeptical that the flywheel is the issue is because when I decouple the transmission and spin the motor up with the flywheel assembly still on it, the vibration issue goes away. That strongly suggests to me the problem is in the transmission, or the interface thereof. The motor is meant for automotive applications. It's been used in several other cars by EV West nearby here, all with a similar setup of standard flywheel-clutch assembly mated to an existing transmission.

UPDATE: I took the Z over to a local transmission shop this morning. Showed them the problem, they said they'd do their standard diagnostic for $95 and 90 minutes. 3 hours later they call me to come pick it up, and they didn't charge me because they couldn't figure out what the issue is. Their only suggestions were flywheel-clutch-pressure plate imbalance (though I told them before and after that I'd just had them balanced), or put a counterweight on the auxiliary front shaft of the motor. I showed them the video of the transmission input shaft wiggle, they said that's not too bad and shouldn't be the source of the problem. Also showed them the videos of the motor revving with the flywheel assembly on it but separated from the transmission, they didn't really have a response to that. I might try another shop, but I'm feeling pretty discouraged at this point.

I inspected that stuff when I had the motor out yesterday and didn't see anything that looked off. Sure it's possible something's wrong there, but I'm skeptical that's the primary source of this vibration.

Ah I see what you're saying. If that were the issue, shouldn't things behave with the clutch pedal pushed all the way in? Likewise, if the collar is too tall and the clutch is partially disengaged at rest, wouldn't I experience it slipping if I accelerate hard from a stop? Since this is an electric motor remember, we can let the clutch engage at a stop, and just dump the throttle. I have done so in first and second gear several dozen times on this setup and never felt the clutch slip. If anything, the driving experience suggests the opposite issue; the clutch feels like it's almost not fully disengaged sometimes when shifting. I had planned to adjust the clutch pedal throw later on to address this as it wasn't that bad but just sometimes annoying.

I... don't know? I got a Duralast clutch kit from Autozone that's supposed to be for this car. The throw out bearing that came with it looks just like the one that was in the transmission when I got it, and seems to fit on the existing collar just fine. How can I verify it's the right one?

I agree it's weird I've had to do so much, which makes me think it's not the flywheel/pressure plate. Yeah the transmission shaft is right on the axis, but if it's being allowed to wobble/move off axis, that would induce a lot of vibration by moving a lot of mass attached to it further out. I don't know, maybe I'll take it to a local transmission shop to have them listen to the noise at least. I'm running out of ideas for what else it could be.

I agree it's certainly possible the shop screwed up. But I disagree that the electric motor is exposing small imbalances that would otherwise go unnoticed. The vibration is severe at high RPM, and even with a gas engine it would surely be very noticeable above 5000

Reinstalled motor after grinding down the transmission input shaft at least a 10th of an inch, still get the same vibration as before. At least I'm getting pretty good at pulling/installing this motor, took 30 minutes to get it back in this time!

That's fair, I will put the motor back in this afternoon and verify.

Yeah the marks on the flywheel and the one on the pressure plate bother me. I do not know if the shop checked them last week, but they did resurface the flywheel 6 months ago (before the ~100 miles I put on the car in the past month). Pressure plate was brand new so it'd better be flat. Would that cause vibration even with the clutch engaged though? I can see how it would cause issues while trying to engage the clutch.

Thanks for the second opinion, mine is clearly not as bad as yours there. If that input shaft wobble is not the source of my vibration issues, what does that leave as a possible culprit? The clutch disk looked totally normal and flat when I removed it earlier today. I did grind down several thousandths off the end of the transmission input shaft to address the interference issue with the motor shaft, but I can't imagine that's the ultimate source of these vibrations.

Behind the bushing is the end of the motor shaft. The features/marks there are damage to the shaft. Pilot bushing fits perfectly on the transmission input shaft, no slop there. Someone on another forum looked at the gif of the transmission shaft wiggling (click the link) and said that's fucked. Can anyone else verify that's too much play? Current theory: Transmission input shaft bearing is bad, leading to play in that shaft. As that shaft moves around, it also rubbed on the motor output shaft (due to about 0.004" of interference, according to my measurements) causing the marks in the images above. But the main vibration culprit is likely the transmission input shaft having play in it, right?

I think it's the transmission input shaft interfering with the end of the motor shaft. There's visible damage to the end of the motor shaft: Also some scoring on the pilot bushing, perhaps a result of the induced vibration idk:

Just separated the motor and transmission again, and there is some play in the transmission input shaft. I can wiggle the end of it maybe 1mm in any direction, is that too much? Could it be a transmission shaft bearing? Here's an 8 sec gif of that slop: https://i.imgur.com/4qlxcj8.mp4

Hrmm, bent clutch disk is interesting. I put about 100 miles on this setup before I had the pressure plate balanced this week. When I pulled it from the car, I noticed a worn spot on the otherwise new pressure plate: There was also some wear on the flywheel, which was resurfaced before that 100 miles: is this the kind of thing you’d see with a bent clutch disk? Or does this suggest a different problem?