bawfuls Posted March 3, 2019 Share Posted March 3, 2019 (edited) Background: Bought a '77 280Z unmodified with original 5-speed transmission, got the L28 limping along briefly (3 cylinders were missfiring), then pulled all combustion components and converted the car to fully electric drive. Now there is significant vibration at higher RPM (starts by 3000), which I assumed meant flywheel was not balanced well (I had the flywheel alone lightened slightly and balanced earlier). So I took the full flywheel and pressure plate assembly back to the local shop to re-balance. Got my flywheel-pressure plate assembly back from the shop this week. They said it was very imbalanced, 12g off. So much so, there wasn't enough material to remove from one side of the pressure plate, they had to weld on a bit to the other side. Here's what that looked like: They also marked pressure plate and flywheel with paint to make sure I reasemble it in the proper orientation. Here's the one picture I took at that step of the process (from the 'gram): You can see the orange paint tick in the bottom right. Problem is, the thing still vibrates just as much at higher RPM as before! There is also an audible click/tick or something at low RPM. Here are two videos showing what it sounds like with the transmission attached, revving up to 5000+. Camera is pointed at the shifter to see it bounce around because the tach isn't working presently. First, with the transmission in neutral: Same thing but holding the clutch pedal in all the way: Separated motor from transmission, left flywheel assembly attached. Clicking is gone, and I did not get any of the vibration from before, I think. It is difficult to judge, it’s certainly still makes (some different) noise at high RPM but when exposed like this the assembly moves a lot of air too. Here is a low-speed video: And one from ~3000-5000 RPM: This suggests the issue is in my transmission right? I am trying to remember the behavior when I first got the car running (poorly) on the original engine. I don't remember the loud vibration, but it's possible it was simply drowned out by the engine before. I do remember it felt like a lot of heat coming up from the transmission through the shifter hole in the body, but I wasn't sure if this was a transmission issue or just excess engine/exhaust heat seeping in b/c of a lack of insulation. I realize diagnosing by sound over youtube is tough, and that this motor-transmission sounds weird because there's no combustion engine over top of everything, but the motor itself should be a LOT quieter than this, it's mostly that high pitched whine you can hear at some points in the videos. I’m not sure how to diagnose from here. Any suggestions of further testing to isolate the issue? Edited March 3, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 3, 2019 Share Posted March 3, 2019 (edited) 2 hours ago, bawfuls said: Background: Bought a '77 280Z unmodified with original 5-speed transmission, got the L28 limping along briefly (3 cylinders were missfiring), then pulled all combustion components and converted the car to fully electric drive. First, with the transmission in neutral: Same thing but holding the clutch pedal in all the way: Separated motor from transmission, left flywheel assembly attached. This suggests the issue is in my transmission right? I’m not sure how to diagnose from here. Any suggestions of further testing to isolate the issue? I didn't watch any of the videos. Too much time, I like words. Did it vibrate when you held the clutch pedal down? Disengaging the transmission from the engine and flywheel? Did you install a pilot bushing in the main/drive/"crank" shaft? If the nose of the transmission shaft is not supported and centered it will orbit around a center point. Off-axis. When you disengage the transmission, using the clutch, the main shaft of the transmission stops spinning. Edited March 3, 2019 by NewZed Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 Yes, it still vibrates when I hold the clutch in, though not as much initially (ie at low rpm). Yes there is a fresh pilot bushing in the coupler on the motor side (takes place of the crank shaft). Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 4, 2019 Share Posted March 4, 2019 With the clutch disengaging the transmission the pressure plate and flywheel spin around the clutch disc and transmission main shaft. If the transmission is in gear and the clutch pedal depressed it should be like the transmission is not even attached to the engine. When you engage the transmission the imbalance is probably magnified by the extra mass of the transmission input shaft. You must have done some machine work to make the end of the motor's drive shaft look like the end of a Datsun engine's crankshaft, for the pilot bushing and the to mount the flywheel. Seems like you might have something off there. The "coupler". Good luck. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) Yes the coupler is meant to mimic the stock engine output shaft. It was machined professionally by a company who makes these specially for EV conversions. I have previously used a dial gauge to check the flywheel runout (0.005” variance) and checked the coupler at that time as well. It came in even better, <0.002” variance. I’d be surprised if the coupler is what’s imbalanced. It’s possible the six flywheel bolt holes on it aren’t concentric, but again that would be quite a surprise. The coupler presses perfectly into the back of the flywheel, and the bolt holes line up with the flywheel easily, so for them to be eccentric would require their eccentricity to match the eccentricity of the outer rim of the coupler as well. I did not attempt to measure their eccentricity when I received the coupler initially. If I pull everything apart again this week I can check. Here’s what the naked coupler looks like on the motor: https://imgur.com/6U8VVsJ and here’s the coupler with the bell housing adapter installed on the motor as well: https://imgur.com/5ZaaylP Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 4, 2019 Share Posted March 4, 2019 Okay, I watched the videos. They're actually very short and kind of cool. I wonder if your clutch disc is bent. Not uncommon, if you let the transmission hang on it by accident. That might cause some drag even with the pedal depressed and vibration. You could put it back together without the disc and give it a test. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 4, 2019 Share Posted March 4, 2019 Don't overlook either, the old backward clutch disc. Springs toward the bolts can cause rubbing on the bolt heads. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 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? Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) 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 Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) 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: Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
bunkhouse Posted March 4, 2019 Share Posted March 4, 2019 Slide the pilot bushing onto the trans. input shaft and check the fit. In the pic above that shows the pilot bushing installed, what is that silver, shiny object just below the brass bushing? Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) 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? Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
ZHoob2004 Posted March 4, 2019 Share Posted March 4, 2019 I don't think that input shaft is particularly bad. Mine was a lot worse and didn't have any vibration issues like you're having. I suppose if you want to try, I think that wobble is mostly caused by the needle bearing that keeps the input shaft concentric to the output shaft. Mine for comparison https://i.imgur.com/kn92ETY.mp4 Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) 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. Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
madkaw Posted March 4, 2019 Share Posted March 4, 2019 So doing all those checks - was flatness of the flywheel checked again? Looks like burn marks on the flywheel Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 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. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 4, 2019 Share Posted March 4, 2019 25 minutes ago, bawfuls said: 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. I can. You had the input shaft bound up between its bearing and the end of the motor shaft. It's going to be cocked slightly, no way to rotate on-center. All transmission input shafts have some play in them. I had four in my garage at one time, they all have play. The bearing in the transmission is a ball bearing, balls in races. There's play, it's not a needle or a tapered roller bearing bearing. That's why the pilot bushing is so important. I think that you might have found your problem, the bind between transmission bearing and motor shaft. I wouldn't spend any extra money until you put it back together with things they way they're supposed to be. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 That's fair, I will put the motor back in this afternoon and verify. Quote Link to comment Share on other sites More sharing options...
NewZed Posted March 4, 2019 Share Posted March 4, 2019 5 minutes ago, bawfuls said: Would that cause vibration even with the clutch engaged though? I can see how it would cause issues while trying to engage the clutch. If you engaged the clutch with the input shaft pushed off-center it will be orbiting around the true center. Probably pushed to one side. Is your pilot bushing set right? Seems like the input shaft was pressing on it. Quote Link to comment Share on other sites More sharing options...
bawfuls Posted March 4, 2019 Author Share Posted March 4, 2019 (edited) 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! Edited March 4, 2019 by bawfuls Quote Link to comment Share on other sites More sharing options...
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