# 1977 280Z conversion: Diagnosing flywheel/transmission vibration



## bawfuls (Jan 8, 2018)

Background:

Bought a '77 280Z unmodified with original 5-speed transmission, got the original L28 limping along briefly (3 cylinders were missfiring), then pulled all combustion components and converted the car to electric (NetGain Hyper9, 5x Tesla modules). 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:
https://i.imgur.com/wraQxpx.jpg
https://i.imgur.com/GnAMYwO.jpg

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):

https://i.imgur.com/6vcQ6GP.jpg

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. 

https://www.youtube.com/watch?v=v2_fJg3tt4E

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:
https://www.youtube.com/watch?v=gJ6g-Hl5p5E

Same thing but holding the clutch pedal in all the way:
https://www.youtube.com/watch?v=js9r8MhLoJ8

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:

https://www.youtube.com/watch?v=Id6O-Xzl5mY

And one going up to ~5000 RPM:

https://www.youtube.com/watch?v=QgRWKg334O8


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’m not sure how to diagnose from here. Any suggestions of further testing to isolate the issue?

I posted this on a Z forum as well, but those folks have no experience with EV conversions so they're unfamiliar with what things should sound like absent an ICE, figured I'd post here too.


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## electro wrks (Mar 5, 2012)

Getting this part of a conversion right seems to be a real problem for some folks. Have you checked the FW axial and face runout? If you can show us the coupling/hub system you are using, and how it's put together, that would be a real help for us trying to help you. Are you using a pilot bearing?

Is that a CanEV adapter plate (or other manufacturer)you're using? Are you using all of the alignment features? Dowels, machined step(s)?


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## piotrsko (Dec 9, 2007)

I know it aint a diodge, but, Being a dodge fan, some of their engines were internally balanced, others were not depending on block. The flywheels were interchangeable except for that balancing. In order to mount a 360 flywheel on a 318 small block you had to remove the balance tabs.

Is your engine balanced this way? Sounds like the shop set it up for external balance because of the tabs and orientation marking. The electric motor is already internally balanced and doesn't need much if any external help.


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## coleasterling (Feb 29, 2012)

This isn't relevant to you question, so sorry I'm not any help there, but other than the vibration, do you find performance to be adequate? Do you think it would be if you went direct drive?


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## galderdi (Nov 17, 2015)

Seems lke alignment would be a likely cause. You can get away with a very small misalignment but if the misalignment is too big it would result in vigrations like you described. I would check the adaptor plate. Maybe see if you can find the centre of the whole in the adaptor and check if the centre is aligned with the input shaft/spline of the gearbox.


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## bawfuls (Jan 8, 2018)

I have checked the flywheel runout (face and side) and found about 0.005” variation for each

I am using the CanEV adapter and coupler/hub. There is only one alignment dowel location which interfaces properly with my bell housing. The others on this adapter don’t come close to holes in the transmission.

https://imgur.com/6U8VVsJ
https://imgur.com/5ZaaylP

There is a pilot bushing. It slides smoothly over the transmission input shaft (I checked this week). It also sits just right inside the coupler/hub. Here is a pic of that which also shows something else: damage to the end of the motor shaft.

https://i.imgur.com/NUxWOE7.jpg

I saw this and rechecked my notes from the original assembly. Sure enough, when I measured the transmission input shaft protrusion from the bell housing, and the motor shaft depth in the adapter plate, there was 0.004” of interference. I have pictures of the motor shaft before install and it was clean, so this was at least part of the problem. This week I ground about 1mm off the end of the transmission input shaft (about half the chamfer depth). The vibration persisted despite this. 

I do not believe the original L28 engine was internally unbalanced. The flywheel was balanced with the assumption that the motor is internally balanced. The flywheel was lightened, resurfaced, and balanced alone six months ago. Then after discovering this vibration, I had it balanced with the pressure plate, hence the paint mark. I am going to get the flywheel assembly rechecked tho, because now I’m suspicious.

I did a test fit of the adapter on the transmission before mounting he motor, but I didn’t have laser levels to locate the center of the hole. I should have used string to be sure. It looked good by eye but that’s not precise.

Another wrinkle: today I took the car to a local transmission shop for a diagnosis. Demonstrated the issue for them, explained what I’d done thus far, and left them to it. 3 hours of work later, they called me to say they weren't charging me because they couldn’t find the issue. Best guess was the flywheel is still out of balance.

Performance is good aside from the vibration! My suspension is WAY out of whack right now (front end very high because of the weight shift, my batteries are in the rear), that’s the biggest drag on performance currently. I am waiting for scales so I can weigh the car before ordering new springs and coil over kit to lower and adjust.


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## electro wrks (Mar 5, 2012)

"I am using the CanEV adapter and coupler/hub. There is only one alignment dowel location which interfaces properly with my bell housing. The others on this adapter don’t come close to holes in the transmission."

There should only be one other dowel. And, both dowels need to be a tight sliding fit in holes in the transmission bell housing for proper alignment. Are you sure sure you have the stock or the correct transmission the adapter plate is designed to fit? Are there some burrs or junk in the holes? Are the dowels damaged? Check them to see they are not modified, offset ones:https://shiftsst.com/media/wysiwyg/Tech/High_Side_Low_Side_Dowell.jpg

When the parts were bolted together with the interference between the motor shaft and transmission input shaft, the bearings or other parts in either or both of them could have been damaged. Also check the pilot bearing(it looks like it's a bushing) again for wear or damage. 

I recall the maximum recommended runout for the flywheel face is ~ 0.006" for this engine. So you're close to the max. It looks like you have a set screw over key way type coupling. You might try adjusting the torques on the set screws to reduce the runout. There is a trick where you can lightly peen the metal on one side of a hole (the coupling bore in this case) and scrape the bore on the opposite side to move the hole slightly, to correct for misalignment. A job probably best left to a Pro, if your not sure about doing it yourself.

Also, the set screw over key way coupling may not be a very tight fit on the motor shaft. To make up for this you can machine a step in the coupling bore behind where the pilot bearing sits, and add a bolt and heavy duty washer to clamp the coupling onto the motor shaft or end bearing. Most motor shafts have a threaded hole machined in their ends. It looks like yours has gotten messed-up. You'll need to clean it up and chase the threads. If there's not a threaded hole, it might be worth it to make one.

For clearance for the bolt and washer, you would also need to fab a new spacer that goes between the motor and the adapter plate. It needs to be machined to transfer the motor shaft to transmission alignment. The coupling should push against the inner race of the motor output shaft bearing or a step on the shaft so it can clamp onto the bearing or step and not move around. Another spacer on the shaft may be needed to do this.


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## bawfuls (Jan 8, 2018)

Yes it’s a pilot bushing, and yes there is a mark on it. I think I have a spare I can swap in.

https://i.imgur.com/K2NFwM6.jpg

None of the other holes in the adapter plate even come close to aligning with holes on the transmission bell housing. Just the main locator pin and the four bolt holes. This is the stock 5-speed transmission, and the bell housing is the same for the 4-speed version and several other Nissan transmissions. Recently, the CanEV kit was used by EV4U (youtube) on a 1978 280Z without issue. I am open to the possibility that CanEV screwed something up in manufacturing and mine is misaligned somehow, though considering it took 8 months between ordering and receiving these parts from them, I sure hope that’s not the issue.

The coupler is EXTREMELY tight over the motor shaft. It actually measures a smaller ID than the motor shaft OD. In addition to the set screws, there is a key way and we had to heat the coupler a lot to get it on. The first time we tried, we didn’t heat the fat end of the coupler enough and only got it half way on the motor shaft. Had to go rent the biggest puller they had at AutoZone the remove it and try again. I am very confident that there is zero motion between the motor shaft and coupler.

I do worry the original interference between shafts damaged some bearings. The trans input shaft has some slight play in it:

https://i.imgur.com/4qlxcj8.mp4

But I showed this clip to the transmission shop and they said that’s really not too bad, and not severe enough to cause my issue. I posted it on a Z forum and someone there said theirs was even worse (and posted video) but theirs did not have the severe vibration I’m getting.


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## electro wrks (Mar 5, 2012)

Yes, that amount of play is normal even for a new transmission. The bearings that support the input shaft inside the transmission are very close together( in some designs, they actually overlap), and don't support it very well. And, even with that play, the shaft needs to be aligned to within ~0.005" of the centerline of the transmission and motor shaft. These are the functions of a well supported and located pilot bearing.


Just to clarify: If you hold the adapter plate against the transmission bell housing with no mounting bolts in place, you can only get one of the dowels to fit in the dowel holes in the bell housing? If this is the case, how far off is the second dowel from the hole?


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## bawfuls (Jan 8, 2018)

electro wrks said:


> Just to clarify: If you hold the adapter plate against the transmission bell housing with no mounting bolts in place, you can only get one of the dowels to fit in the dowel holes in the bell housing? If this is the case, how far off is the second dowel from the hole?


Yes, the one dowel up top lines up, and the four bolt holes line up. No other dowels are anywhere close. Here is a picture of the adapter plate lined up to the bell housing without the motor on it. The top alignment dowel is engaged (circled in yellow). The four holes cirlced in blue are the bolt holes. The holes circled in green are outside the wall of the bell housing completely. The hole cirlced in black does line up with a hole on the bell housing, and could take a second dowell, but it did not have one in it when I received the adapter. The black circled hole lines up with a threaded hole in the bell housing; it is used to mount the starter in the stock configuration. I could try to find the one that was in the bottom green hole (I pressed it out) and press it into the black hole, but with the threads in the transmission side, that seems unlikely to help alignment.

But considering how well the existing dowel and 4 bolts line up, I have trouble believing that this second dowel would solve the problem.


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## electro wrks (Mar 5, 2012)

In this photo, the blue circle to the far right is where the second dowel is located. It is a hollow dowel that has a bolt that goes through it. Along with the top yellow circled dowel(solid in this case), that's it for dowels. There should be no more dowels needed or used with the ICEes photos I've seen.

Again, ignore the bolts. Pull them out and put them on the bench in a nice little pile. Will the plate fit flush on the bell housing with the two dowels shown(the solid one and the hollow one) engaged in their holes? If they do, the bolt holes need to be cleaned-up(enlarged slightly) to fit the bolts. It is not that uncommon to have to do this. The primary alignment is done by the dowels. The bolts have very little to do with the alignment and mostly are there to clamp everything together. They are not manufactured to close enough tolerances to be able to do this in this case.

This presupposes you have the right plate from CanEV!


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## bawfuls (Jan 8, 2018)

electro wrks said:


> In this photo, the blue circle to the far right is where the second dowel is located. It is a hollow dowel that has a bolt that goes through it.


Oh, yeah that is still there and it lines up just fine.


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## electro wrks (Mar 5, 2012)

bawfuls said:


> The coupler is EXTREMELY tight over the motor shaft. It actually measures a smaller ID than the motor shaft OD. In addition to the set screws, there is a key way and we had to heat the coupler a lot to get it on. The first time we tried, we didn’t heat the fat end of the coupler enough and only got it half way on the motor shaft. Had to go rent the biggest puller they had at AutoZone the remove it and try again. I am very confident that there is zero motion between the motor shaft and coupler.


I've seen some really chewed-up shafts that had this kind of set-up, and supposedly a tight fit. Keep the bolt and heavy duty washer clamping idea as a back-up plan if you start hearing more noises or feel the clutch action start acting-up. It would be a shame if heavy torque and regen cycles loosened your coupling set-up, and ruined the shaft on this very expensive motor.


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## Bruffie (Feb 24, 2019)

Interested! Datsun fan from way-back. Have owned a 240Z for 22 yrs. (New Zealand's very first) so thank God you are not bastardizing a 240, an old 280 is OK. Some random thoughts.1/ I have seen your test runs and pictures. Running the trans. in neutral, the input shaft is still spinning. Put it in a gear with clutch IN and nothing in the trans. will be moving. 2/ What have you got for engine mounts? Rubber mounts going down to the old cross-member? How about a "torque-rod" from the top of the motor to the body work? Your videos only show it free running, does it still do it while driving. Or load it up with the clutch when parked, will that settle the vibs.? If so then a torque rod is needed. 3/ A second dowel hole would be about 180 degrees from the 1st dowel but don't think that is the issue. 4/ Have just had a thought about the free running/reeving that you've been doing with it (how do I explain it). With those shafts and gears free spinning in the gearbox (and in thick oil) they are back-lashing etc and may just be setting up resonance at certain speeds. Again putting it under load would test that theory along with the torque rod idea. Ken


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## ryry (Aug 17, 2012)

I reckon that youve busted a tooth on the secondary shaft in the box, as previously posted above i think you should try revving and leave it in gear and clutch depressed, because then the box will be still.
Although that dosnt rule out clutch plate running ofcenter to motor( i would assume you still have the spigot bush/ bearing in your setup for with out that you might have an issue.
Tell us how you go


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## bawfuls (Jan 8, 2018)

Yesterday I tried the test these last two post are suggesting. Put the car in gear, pushed clutch pedal in all the way, pulled the handbrake, and revved. Same vibration as usual. 

Also yes it shows up driving as well, when I drive the car I shift when the vibration starts to pick up.

As for motor mount, I build a mount that bolts up to the stock motor mounts, retaining all the stock rubber there. Here’s what that looks like:

https://i.imgur.com/O0ZI1IC.jpg


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## ryry (Aug 17, 2012)

Maybe you have a bent input shaft


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## electro wrks (Mar 5, 2012)

One trick to rebalance the flywheel clutch set-up, if you think there is balance a problem, is to add extra washers under the pressure plate mounting bolts. Add the washers under the bolts in different positions until the vibration is reduced. Then adjust the number of washers, if needed, to further reduce the vibration.


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## Bruffie (Feb 24, 2019)

Have gone back to your original post and read it word by word as follows...... 
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.
"did not get any of the vibration from before, I THINK" and then "It is difficult to judge".
I know exactly what you mean by that. Maybe the motor/fly-wheel assembly is a problem but because it is now a very compact unit (without the gearbox hanging off the end of it--acting like a "tuning fork".
Next idea. Drop the box off the motor again (only 4 bolts), clamp a long thin bit of steel to the adapter plate this is now your new "tuning fork" and run up the motor again. 
Then if you are still not certain get a guy in that can put some kind of frequency meter on the motor (still with the box off). There are people out there that balance industrial machinery with meters and scopes.


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## Mark72Newk (Sep 16, 2020)

Hi,

Did you end up solving your vibration issue?
If yes, what was the cause?

Thanks, 
Mark.


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## bawfuls (Jan 8, 2018)

I never got to the bottom of this. I just tend to ignore it and shift around 3-4k rpm. The issue hasn’t gotten any worse in these two years of driving.

I want to eventually redo the car with a small Tesla drive unit and ditch the transmission. Kinda wish I’d gone that route initially, live and learn.


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## Splatterpus (Jul 19, 2021)

Sorry to read of your transmission issues. 

Did they ever resolve or did you swap for the Tesla unit?

I've got a 1956 190sl with a Ford drivetrain (previous owner gave it a V6, C5 automatic transmission and a live axle) that I've been looking to convert to a Hyper 9 system.

Other than the transmission issues, how was your Datsun around town? 
Could it handle Sepulveda Pass?

Were you able to work out the weight distribution issues?

Thanks!


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