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Diagnosing flywheel/transmission vibration


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1 hour ago, ZHoob2004 said:

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

 

Just to add an illustration.  The main drive gear, as they call it, is pretty short.  The needle bearing is between the main shaft (9) and the drive gear (1).

 

image.png.184b79bb6b09f655a17c651c30474044.png

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2 minutes ago, bawfuls said:

Reinstalled motor after grinding down the transmission input shaft at least a 10th of an inch, still get the same vibration as before.

 

Always a possibility that the shop that ground your flywheel and balanced your parts didn't get it quite right.

 

Maybe the smoothness of the electric motor is exposing what are actually small imbalances.  Good luck.

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Sounds like something heavy then.  Flywheel or pressure plate.  The transmission shafts don't have much inertia, near the center of the circle.  With the clutch in the pressure plate is disengaged from the clutch disc, which itself has negligible mass, and transmission shaft.

 

See if one of your friends has a flywheel, clutch disc, and plate setup in their garage.  Maybe they'll let you borrow it just for a test.  I have two myself but I'm in Oregon.  Most of us don't have our parts balanced, they come just fine from the factory or the store.  It's weird that your guys had to do so much.

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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.

Edited by bawfuls
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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?

Edited by bawfuls
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His main point was the collar, AKA sleeve.  The part with the two ears on it that the clutch fork sits on.  It needs to match the pressure plate.  It's possible to get a tall pressure plate and a tall collar and have the clutch partially disengaged at rest because the collar is pressed against the front of the transmission cover.  It's a good point.

 

Here's an old thread about how to go wrong.

 

https://forums.hybridz.org/topic/43715-changing-the-slave-for-more-pedal-throw/

 

 

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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. 

Edited by bawfuls
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It's just another part of the system to make sure is right.  A bad bearing, broken "nose" piece on the transmission where the collar rides, cracked clutch fork, worn out pivot ball, clutch fork not seated properly on the pivot ball, etc.  Anything that could be causing uneven force or imbalance on the pressure plate fingers.  

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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.

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1 hour ago, bawfuls said:

Their only suggestions were flywheel-clutch-pressure plate imbalance (though I told them before and after that I'd just had them balanced),

 

I've seen many times where the assumption that the one thing that should be the problem can't be the problem because it's already been checked or fixed, often ends up  being the wrong assumption.

 

Everybody is suggesting, in essence, that you try another flywheel and pressure plate.  It's the obvious next step.  The Nissan flywheels and pressure pates are all externally balanced.  Any parts you grab should be worth a try.  Your balancing guys did a crazy amount of work on that pressure plate.  Very abnormal.

Edited by NewZed
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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.

Edited by bawfuls
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On 3/3/2019 at 1:40 PM, bawfuls said:

Problem is, the thing still vibrates just as much at higher RPM as before!

 

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.

 

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.

 

Seems like you're stuck in a "think loop".   You need to do.  Think-do-think-do...  If you think it's the transmission, find another to bolt on there.  90% of people who have a Z have their old 4 speed sitting around somewhere.  I do.

 

You didn't sound so confident that the motor might not be the problem, in your first post. You put "I think" after your comment.

 

Why would you take it back to the guys that might not know what they're doing?  You're just going to watch them do the same thing that didn't work the first time.  

 

My car had a lot of heat through the shifter hole when I was missing the rubber seal.  That was with everything working perfectly.  Just a lot of hot air down there.

 

If you want to get a little crazy, drill a hole in your transmission so you can see the input shaft.  Maybe you'll see a misalignment as it spins. 

 

Or, here's a way to be sure that the input shaft is not turning - put the transmission in gear with the rear tires locked.  Maybe on jack stands with the parking brake set.  Hold the clutch in and do the rev test.  The transmission input shaft can't turn so all you have is the pressure plate and flywheel spinning around the clutch disc.  That takes all of the rotating part of the transmission out of the picture, but with everything hooked up.  If you still get a vibration make note of any burning clutch smell, in case you're not getting full disengagement.

 

Don't do it with tires on the ground, if your foot slips you might blow a hole in the back of your garage.  Or just make sure it's pointed the right way.

 

One last thing on the pressure plate.  Maybe it has some broken parts inside, they do break.  That might be why they had to get so crazy with their drilling and welding.  The loose parts might be moving when you press the pedal, maybe the thing is unbalanced now.  Of course, if that's the case, then it would make sense to go back to the balancing guys.  Or just swap pressure plates.

 

Just suggestions.  Good luck.  Thanks for the puzzle.

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8 hours ago, jonbill said:

I may have missed it, but how did you ensure the motor output drive and gearbox input shaft are perfectly in line? That's the complete one-off so surely the most likely source of errors. 

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:

 

IjdN4A4.jpg

 

Today I will try the test NewZed posted in bold and report back.

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19 hours ago, NewZed said:

Or, here's a way to be sure that the input shaft is not turning - put the transmission in gear with the rear tires locked.  Maybe on jack stands with the parking brake set.  Hold the clutch in and do the rev test.  The transmission input shaft can't turn so all you have is the pressure plate and flywheel spinning around the clutch disc.  That takes all of the rotating part of the transmission out of the picture, but with everything hooked up.  If you still get a vibration make note of any burning clutch smell, in case you're not getting full disengagement.

 

Don't do it with tires on the ground, if your foot slips you might blow a hole in the back of your garage.  Or just make sure it's pointed the right way.

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...

Edited by bawfuls
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