Tailshaft Vibration Massively Improved

Well the homebrew balancing paid off.
I couldn't feel any vibration at all at 60 km/h and it didn't become evident until I hit 77 km/hr - even then it was only just detectable on a smooth road.
The vibration must have been my speed limiter when driving a I had to watch my speed very carefully on the way to work.
So it's definitely the tailshaft so it looks like I have to find someone who will do an ultimate balance.

The hugely diminished vibration and the new rear sway bar link bushes I put in a week ago (sorry not blogged) made for a very pleasant trip to work.

I have also sealed the front windscreen across the top in the body-to-rubber interface so I'll see how that goes this week. I have had some minor leaks. (I have a tendency not to use any sealant unless I absolutely have to.)

Some Home Brew Tailshaft Balancing

I finally devoted some time this weekend to attempting to improve the vibration issue with the Vogue's tailshaft.
I had bought a 3 axis accelerometer from eBay a few weeks ago and on Saturday I added some connectors and wires so I could select any of the 3 axis to test. I choose the 'Z' axis output set to high-sensitivity, and added some orange bluetack (yes, really)  to the bottom of the PCB to hold it on the motor frame.
The bluetack colour got washed out on this picture as and appears white.

Up the Vogue went onto axle stands with the rear wheels removed for safety.
I cleaned some road dirt off the motor frame and stuck the accelerometer on.

Then  I limited the motor speed to 3500 RPM which is 87 km/hr so that the tests would be repeatable - all I have to do is floor the accelerator.

I dug out my 38 year old 12V power supply and the CRO.
 
First trace. There was a lot of motor controller PWM noise but the vibration waveform was clear. I later added a 500Hz single pole RC filter which cleaned up the motor PWM noise - sorry not shown here. So the start point was 100mV P-P.

I wrapped some masking tape around the motor end of the tailshaft and marked it in four sections. Then I applied a stainless steel hose clamp and tried all four sections to see if there was a change.
Results:
1  200mV
2 30mV
3 160mV
4 175mV

Then I tried in between but I couldn't do better than the result in number 2.
I increased my test speed to 4100 RPM (102 km/hr) and tried all again. The vibration increased to 50mV with the clamp in the best spot - about 1.8.

Picture here is with the clamp at about position 2.5.

I tried adding a small washer but there was a slightly worse result.
I tried cutting off 5mm of the protruding part of the clamp, but if anything, the result was slightly worse. It was hard to tell.

So I left it at position 2.

Conclusion: It is possible to significantly improve the vibration problem.

Curiously, position 2 is where all the balance weights are currently welded.

Not sure what to do next - thinking...
I'll drive it tomorrow.

First step toward building an on-vehicle Tailshaft Balancer

I alluded to this in my previous post and I realised that I should elaborate on my intentions regards tailshaft balancing.
The final straw of getting help with the tailshaft issue came after I rang a Ford service manager and enquired into on-vehicle tailshaft balancing. I had read on a couple of Ford forums that some Fords required the final tailshaft balance to be done on the vehicle.
The service manager was very helpful and pointed out that the balance is done in conjuction with a diagnostic tool that plugs into the car's ECU (that's not what I thought but he was adamant that it only worked with Fords). No hope there.

So, I have bought one of these off eBay. It's a three axis acceleometer with analogue outputs.

It claims to be highly sensitive. (So is our dog [the rag stealer] but she hasn't helped. She's only allowed on the bed if she has just been washed and someone is sick - special times).

I'll be making up some simple electronics to detect one of the output signals and flash a high-intensity LED at some repeatable point. It then should be a matter of:

1. Secure the accelerometer board to the motor frame.
2. Shine the LED at the tailshaft
3. Run the car on axle stands

Of course nothing is ever simple so I'll start by looking at the signals on a CRO and seeing what I've got.

I'll use hose clamps initially and place one on the tailshaft to deliberately mis-balance it so I can calibrate it all.

Then the whole shebang should tell me where to place the balance weight. From there it's should be just a matter of varying the weight to minimise the vibration.

I make a big effort to blog this as I go, success or not!

On other matters - we had a really nice storm last night and the Vogue was the last car home so had to be charged in the pouring rain. No problems. The plug was dry when I unplugged the EV "special" extension cord. In fact I was more concerned about leaks in my new rubber seals (windows, doors) throughout the car - also no problems (hmmm - see later posts).

Three more fuseholders bypassed

I spent about an hour and a half under the front of the car last night squeezing my hands up beside the inner front guard to cut out two of the offending fuseholders (packs #11 and #12), substitute a length of wire, and heatshrink the whole lot. The time was mainly spent trying to line up two pieces of wire (several times) with only one hand (tried many clips etc.) and solder with the other - while scrunched up in strange positions.

I also did the same treatment to pack #8 in the Engine Bay.
Pack #10 inline charger fuseholder is also about to fail. It's the hardest pack to get at without removing the top battery tray so I'm hoping it will hold on a week or so as I will be removing that tray to change the heater blower soon. It's marginal - if you rattle the charger wire while charging, the charger cuts back to balance mode - sigh.

So, fully charged again,  Il drove the Vogue to work today.

Vibration wise. I have now driven the car for a couple of days and the vibration is only a little bit better than it was with the M8 bolts holding the front flange in (allowing the spigot to be centered). While 90 km/h is possible, it feels the the motor bearings won't survive long. It's going to be a wet, cold weekend so I hope that I both get the time, and the enthusiasm to brave the cold and check it out further. I have my hose-clamps ready.

A Tail of Two Flanges - The Tailshaft saga

Reading back over the blog when I first installed the tail shaft I kind of skipped over some of the messing around I had to do to get it fitted.
One of the reasons I didn't blog all of it was that it seemed like a criticism of the guys that made the coupler and tailshaft and the problems were sorted out pretty quickly - but maybe they weren't after all.

Here is the whole story.
The first ever time I installed the tailshaft, it took me a longer time than I would have thought possible to realise that the four bolts that hold the front tailshaft flange to the motor coupler didn't actually line up. The holes in the motor coupler, while being the correct Pitch Circle Diameter (PCD), were arranged equidistantly around the circle. The universal joint flange on the front of the tailshaft was arranged as a rectangle. This is pretty standard for universal joint (UJ) flanges - at least with cars that I have played with.

This picture isn't of mine but shows what I mean. The two holes on the right are closer than the two holes across the top.

That being the case, the first drive of the Vogue had the front of the tailshaft being held to the coupler with two M8 bolts 180 degrees from each other as all four bolts could not be fitted.

Obviously I wasn't going to leave it that way, so before the second drive I removed the coupler and tailshaft and took them back to the guys that made them and they added some holes and tapped them out to M10. (The original M8 tapped holes were left alone).
When I got it all back and managed to find some fine thread M10 bolts of the correct length, I took another huge period of time under the car before I decoded that there was no way I could get these standard hex bolts in past the universal joint ears (the bits jutting out that hold the cups). So a day or two later I bought some M10 Allen head machine screws.

Again I messed around for an hour or so trying to get these in with no success. They fitted through the tailshaft (UJ) front flange OK but would not all thread into the motor coupler when I offered it up. At some point I realised that the tailshaft flange holes were imperial 3/8 inch - that's 9.525mm.
So I pulled the tailshaft out completely, held the tailshaft as best I could in my workmate, and hand drilled the holes out to 10mm - the biggest drill I had. I cleaned up the facing side of the flange with a 1/2 inch drill bit and ensured there were no burrs.

Once the holes were drilled out, I could almost get all the bolts in by hand. Importantly I could now place the tailshaft flange on the coupler flange, mate the spigots up (the 60mm diameter sections used to correctly locate the flanges) and insert and tighten the bolts up. There was always one or two bolts that I had to pull in with the Allen key the last 6mm or so but it all looked correct.

I explained this to the guys that made ther tailshaft and coupler but they weren't too concerned and have had the tailshaft back twice since then.

So now we are up to this week.
When I picked up the tailshaft on Monday night, it was explained that the balance was fine and they hadn't changed much. It fitted it Tuesday night and it behaved pretty much the same way as before. However, this time I had arranged a system were I could control the motor speed while lying under the car so could have a "play" without having to ask someone else for help controlling the speed. What I found was, even though earlier tests showed the front of the tailshaft rotating without excessive runout, that was not the case on the slip yoke. The UJ flange rotated true but the inner part of the slip yoke did not.
I whittled a chunk of wood and tried moving the UJ centers in their housings (in the direction that would remove the runout) - no give at all (they were properly installed and very good).

For some reason I decided to remove the four M10 bolts and track down the two M8 bolts and washers that I had used on the first drive.
Once I had the tailshaft bolted to the coupler with only two M8 bolts, there was an immediate and substantial improvement. I made a further slight improvement by loosening the bolts and using the tiny bit of play in the spigot to move the mating flanges in a direction that would help.

That's how I drove it today - a lot better. Not perfect yet, but better.

It appears that there is a concentricity problem in the front slip-yoke and UJ combination at the front.
If the tailshaft is being held by the front flange during balancing I would think it would be balanced out.
So we know what it is, the front end of the tailshaft involving the slip-yolk and universal joint - now to fix it completely.

A note here. I measured runout months ago and concluded that the tailshaft was fine. The closest I can normally get to the front of the tailshaft is about 300mm from the front, and it's a lot better at that point. I've got a lot braver with rotating machinery (while still being careful) over the time. A whole lot of factors have conspired to create this problem and make it hard to track down. My inexperience hasn't helped.

Edit: Some changes made for clarity thanks to comments from AEVA forum member weber.

The Tailshaft returns

It's back. I'll try to get it on tonight. I need the car mobile for Thursday.

I picked it up yesterday afternoon but there was no great hurry to re-fit it as Jeff from Precision Balancing indicated that there was no significant change (I also cooked dinner last night amongst other things so time ran short). We may have come up with a way to do an on-site balance of the whole drive train while the car is on stands. I'll post when I have more info.

Wedges Installed - Problem persists

I finished installing the two degree wedges on both sides of the car on Sunday afternoon.

This is the front - about 4 to 5mm lift.

This is the rear of the axle perch.

The underside - just 'cause I took the picture.

The differential flange and the motor coupling flange are now within about 0.3 of a degree of each other.

....and the result. Absolutely no change at all!

We even locked the motor speed to 60 km/h to remove any doubt about speed variation and placed a big block of wood under the rear of the motor mount and jacked the car up about 15mm - no change.

I repeated a previous test and jacked under the middle of the motor cradle (the fan end of the motor) - no change in vibration. This stumps me. How can it be that taking so much load on the jack doesn't at least dampen the vibration?

I don't believe I have ever in my life put more effort into a problem with so little return.

So I am faced with a choice now of whether to give up on universal joints and have the tailshaft remade with CVs or persists in trying to find the reason for this vibration. Going the CV route doesn't automatically gaurantee a cure.

Suggestions from mechanically minded folk are very welcome but if you want to comment, please could you read the posts on vibration so we don't revisit older discussions too much (that isn't to say I haven't missed something).

I'm currently trying to ascertain what sized tube wall was used in the new tailshaft.

Ready to Re-assemble Driver Side Spring Mounts

I had wire brushed all the axle/spring mounting hardware a couple of days ago and applied rust converter. I cleaned off the rust converter residue and primed the bits last night. I gave them a coat of gloss black this morning. I can't paint inside the house or in the garage due to overspray, so It's a process of warming up bits (and spray cans) inside, painting the bits outside, then bringing them back in. I guess it doesn't matter much if glossy black bits under the car are slightly dull - but I'd know!

If my hands can keep from seizing up with the cold I'll re-assemble the right hand side tonight.

Changing the Differential Pinion Angle

My spring wedges (sounds like a potato treat with greens), arrived yesterday so last night I set about separating the axle from the leaf spring on one side of the car. I jacked up the car under the diff housing then placed the two rear body jacking points on axle stands. Then I lowered the jack until it was only just supporting the weight of the rear diff/axle.
The U clamps came off pretty easily (with the aid of some CRC56).Once the U clamps were off, I jacked up the axle slightly to removed the top rubber mount.

You can see the leaf spring centre pin that locates the spring on the rubber mounts (next photo).

A slightly blurry picture of the U clamps, upper and lower spring mounts and shiny new two degree wedge.

 

View from the rear of the car.

The spring wedge in the upper insulator/mount. The upper rubber insulators are not in very good condition but I tried unsuccessfully this morning to get new ones. I'll put these back in and keep trying to find a replacement now that I know how easy it is to "drop' the rear axle. I think I'll make a thin wedge to go in that gap in the wedge as well.

The left hand side - still intact. I'm doing one side at a time. That way the "other" side holds everything in place and I don't have to worry that the whole axle will fall out on the floor - tearing the brake lines in the process. The oil stains are an old testimony to (now-replaced) leaking rear oil seals.
I'd love to pull the springs out and clean the whole lot up but I want the Vogue back on the road ASAP. Maybe next year...

A couple of paragraphs from the workshop manual. It's interesting that Mr Rootes sometimes fitted wedges. No, I didn't find any.

Driving my thougths to Vibration

While driving the Vogue every day this week, I seldom go for more than a minute without thinkout about my driveline vibration issue. For the time being, I have found ways to and from work that allows me to keep the speed below 55 km/h except for an approximately one kimometer stretch. I can pull in and let traffic go past then keep speed down here as well - usually. Curiously this makes my 25-30 minute commute about 30-35 minutes. Not a substantial difference but no-one likes to travel slowly when they can legally go faster - and it's frustrating because the Vogue's power curve makes it way more fun at higher speeds.

Anyway my thoughts during this drive waver around in the following direction.
Back when I orginally identified that I had a driveline vibration, my first impulse (after tailshaft
balance) was to think that it was caused by the differntial pinion angle. Essentially a Universal jointed
tailshaft will vibrate a lot if the flanges on either end of the drive system are not at the same angle
with respect to the line of the driveshaft.

We thought we had dispelled this theory by temporarily altering the pinion angle using axle stands and a jack, and moved on to removing the motor, dismantling it and having the rotor balanced.
All to no avail - apparently...

Well, looking back I note in the blog (my reference source for all thing EVogue), that at the time
Laurel (wife) thought it improved but "I was looking for a complete cure". It was after that we balanced
the motor's rotor and didn't see any improvement.

What if there are two problems? What if we have fixed one which was masking the other?

My intuition, and elimination of just about everything else, tells me it just HAS to be diff. pinion angle. Add to this that the Vogue originally had this problem before conversion.
A few weeks ago I was put off this theory when told that up to 3 degrees is fine. But in retrospect, the
fella who told me that is a speedway driver. More investigation yields comments like "3 degrees for up to 400 HP, 5 degrees for up to 800 HP". Hmmm. What out normal street travel? I have dug up many references since then that you should strive for under 1 degree difference - preferably 1/2 a degree. This from lowered car folk who run big sound systems and object to their bass being supplemented by driveshaft wobble.

What it boils down to is that you really have to try it.

With that in mind, I have ordered a pair of 2 inch wide, 2 degree wedges from a 4WD online seller in the
USA. They should be here in less than a week.

I'll install them then make the decision of whether to have a new driveshaft made using CVs.
A CV driveshaft will be vibration free but have slightly more loss than a UJ shaft. Changing the pinion angle will help a keep losses lower in a CV driveshaft anyway.

So, watch this spot - or listen subsonically....

Some Vibration Testing and Thoughts

I have added a new search label to the blog - Vibration!

Someone on the AEVA forums had suggested that the vibration may be resonance in the motor mounting system. I had my heart set on this being the cause - alas no. I'd even measured up for motor cycle steering dampers.
Placing a jack with a block of wood under the centre of the motor frame very marginally decreased the vibration is accord with what you would expect in that it offered a bit of dampening to the real cause. I used my phone to record the subsonic audio coming from the car during axle stand testing. Here is a spectrum plot of the recorded audio with speed somewhere between 55 and 60 km/h.

The lowest peak occurs at about 76 38 Hz which is rotation frequency at 57 km/h - that fits. The next peak is at twice rotation frequency which suggests the universal joint as it rotates over the "top" on each side. The third and most prominent peak is at 118 Hz - which I can't explain - three times rotation frequency?
It still looks like interplay between the UJs and the motor/mounting.

Crawling around under the car travelling at 55-60 km/h (on stands) the vibration was almost non-existant at the diff end. The motor itself was the worst point. I could not visually see any runout consistant with this behaviour. I've had some really bad UJs in tailshafts in my life that didn't vibrate as badly as this apparently OK one.

Precision Balancing have a portable setup for analysing vibration that they use in the field - it may soon come to that.

I'm also thinking about CVs....

Economy for Last Week and Full Current at Stall

Power economy was pretty similar to last week.

Week ending 19th April 2013:
Monday 11.86 for 48.92 km => 145 Wh/km
Tuesday 10.1 AH for 48.1 km => 126 Wh/km
Wednesday 7.33 for 34.12 km => 129 Wh/km
Thursday 9.93 AH for 39.5 km => 151 Wh/km
Friday 10.75 AH for 47.83 km => 135 Wh/km

All battery to wheel.
Thursday was the day I recorded serial logs. Typical that it was the worst day.
The Vogue has now traveled 636 km as an EV.

Friday I played around with different PWM frequencies. I hadn't realised that I wasn't getting full current at stall until I tried 4 kHz flat-top (see previous post). Suddenly I got good acceleration from stationary. The only problem is that 4 kHz is annoying. I tried a few combinations during the day and was only on the last trip to Doncaster (up a significant hill) to pick up William (son) that I tried the last pre-supplied switching frequency combination.

It's 8 kHz SIN auto-switching to 2 kHz  when current exceeds the 8 kHz limited value.
It works perfectly. I had full current from standstill, same as the 4 kHz configuration but no noise when not heavily accelerating. Unlike the 16/8/2 kHz configuration, it apparently applies the correct current limits when switching PWM frequencies.

It made a huge difference. There was a small hill turning out of a driveway that William and I had always wondered if the Vogue would handle once it was going (challenges of direct drive). It was no problem. It may have been another story with the 16/8/2 kHz configuration that I have been running since the car was on the road.

I'm not driving the Vogue this week. I have decided that I'm shaking it to bits (a couple of the chargers have rattled their voltage output down by half a volt or so - trimpot movement) and I need it going for Sunday. With Thursday a public holiday here, I'll do the axle stand thing again and check out Richo's (AEVA) theory that it may be resonance in the motor cradle. I'll also be a lot more critical of which end the vibration is coming from.

All Together Again

The Vogue is all back together. I wish I could say no more vibration but it's still not good. Anyway the Vogue will be my daily driver from now on so I hope to sort things out over the next few weeks while I'm driving it.

Rotor in, Motor in

I have re-installed the rotor back in the motor, fitted the shaft encoder and re-fitted my IP65 spray can lid. The only silicone I had was the high temperature stuff that I used on the heater core. That worked nicely.

I'm glad border adhesive is useful for something (weight). After the huge trouble we had stripping it off my daughter's bedroom wall we swore we would never use it again.

Since I had to wait a day for the silicone to set, I turned my attention to the chargers and controller tray. I am going to drill out all the 4mm holes and use M4 rivnuts so that I can get stuff off the tray without having to remove it (the tray). I ran out and bought a 6mm cobolt drill (for stainless steel - it works really well) and tried to use a manual method to insert the rivnut - no good. I'll take the tray to work and see if I can use the tool there. So the tray is in the boot of the Super Snipe.

The blue circles are some of the 4mm holes - the red is a 6mm hole I have drilled out.
The DC-DC block (still on tray) is another matter. It's held on with M6 bolts through the bottom from inside the case (nuts underneath). It isn't impossible to get off without removing the tray - just difficult.




As of Sunday afternoon, the motor is back in the car.
It took me and William about an hour of messing around with a jemmy bar and many blocks of wood to get the rear of the motor to a height where I could get the Jack under it. From there it was relatively easy.

I have about half the chargers (six) left to modify. I have to change the current shunts in all the chargers to finalize my modifications for two current settings - 3A and 180mA. I have ordered some shunt wire but it's not due for a week or so. I can still finish installing the controller tray since the rivnuts will allow me to install the chargers afterwards.

Daughter board for current switching shown circled.

My two spare chargers (where I tested this modification) didn't need the shunts changed - they were 12 milliohm. The twelve chargers in the car appear to have anything from 6 to 9 milliohm shunts which makes the low current setting too high - hence the shunt change.

The modification allows the charger to charge at 3 Amps then, when the current drops to less than 300mA, the charger switches to 180mA Constant Current - which is the value that the rudman regulators (cell bypass resistors) in my packs are set. It'll means that charging the car is a set and forget operation - which is as it should be.

The Rotor is back!

I just picked up the rotor from Precision Balancing.

The motor rotor in the boot of the Super Snipe.

Before balancing the rotor balance was 7.43g (grams) out at 18 degrees and the other end 14.4g at 191 degrees.
After balancing it is now 0.550 at 328 degrees and 0.532g at 320 degrees.
It sounds a lot like it was statically balanced originally.
They also balanced the coupler after balancing the rotor - it'll need painting again (I'll probably stuff the balance!). You can just see the shaved part of the coupler on the top (red thing on end of rotor).
This will make a big didn't make any difference - now to get it all back together.

Motor Is Out - again

I stripped the engine bay on Saturday, went for a day trip to see a relative in Shepparton on Sunday, and removed the motor on Monday (today). I decided not to remove part of the finished interior to use the "rope trick" to get the motor off the jack.

Picture from July 2010

Instead I had two helpers use a wooden pole to hold the rear of the motor cradle up while I slipped the jack out. I load tested the pole with my weight before trying this. They indicated that they don't really want to help put it back in the same way (It wasn't easy). The red arrow is pointing at the pole - picture taken just before I went inside to fetch Laurel and my daughter's boyfriend to help (no-one is safe!).

Picture today (11th Mar 2013)

Since never got around to taking a picture of how I increased the IP rating of my little shaft encoder I took the opportunity this time. I had siliconed a spray can lid over the encoder - see red arrow. The black steel ring, also siliconed up, has a small gap in the silicone at the bottom to allow condensation to drain. (Blue arrow points to silicone around spray can cap).

I had to remove the spray cab lid again and was pleased that the silicone, which was past "use by" at the time (getting a bit jelly like), held on nicely. I'll use fresh stuff this time.
Shortly after this picture was taken I took the rotor out. It's in the boot of the Super Snipe now.

Driveline Vibration Identified

Last night I removed the driveshaft and ran the motor with coupler still attached. The vibration kicked in at 2000 RPM (50 km/h), faded a bit as the speed increased then kicked in again at 3800-4000 RPM (100 km/h). I removed the coupler and ran it again with exactly the same result.
The vibration was no-where near as bad as with the tailshaft - but quite definitely present and at the same speeds that I am getting the vibration with tailshaft attached.
So the motor is apparently the root cause.

I spoke to Jeff at Precision Balancing (who made the driveshaft) this morning and he asked where the motor was made then indicated that he does lots of Induction Motors for higher speed and the nominal rotor balance is only ever "just enough" for their nominal running speed - in my case 1500 RPM. There was some complication to do with a language barrier around the time I was discussing rotor balance with Qin Wei (the motor manufacturer in Taiwan) - only that they indicated that it would be fine to 4000 RPM..

So I'll strip the engine bay, drop the motor cradle, remove the motor then remove the rotor and take it up to Jeff. He also warned me to check the bearings for a speed rating. They are NSK bearings but I'll have them out anyway when the rotor comes out so I'll check.

Moral - balance those rotors.

A point here is that this probably wouldn't be a problem in a FWD where the motor was hard coupled to the gearbox. The rubber mounts in my case allow some movement that appears to be amplified by the tailshaft.

More on the Drive Shaft

I had Laurel run the driveshaft up to 50-60km/h while I crawled under the car yesterday morning. I placed a hand on the underside of the motor then down under the diff. It's definitely coming from the end near the motor.

Here is a annointed picture of the front of the driveshaft and motor coupler.

Also, to clarify. I understand that the driveshaft can not be on a 0 degree angle from the motor. In the previous post I actually did not measure the drive shaft angle. I was using the motor angle as a reference to try to get the differential pinion angle the same (diff and motor flange faces aligned). Either way, it seems the diff pinion angle is not the culprit.

In search of the Drive line vibration

I placed the Vogue on axle stands on Sunday and removed the rear wheels.

I measured the angle of the motor, so close to 0 degrees that it didn't matter. Then I measured the differential pinion angle. I did it two ways. The first was to place the level across the back of the diff flange. It calculated out at around 2.3 degrees. Then I used a trick I read about on a hotrodders forum. You align the tailshaft so the uni is pointing straight up and place a socket on the needle roller cup. The socket has to be the largest you can fit without it riding on the circlip. Then place the level on the top of the socket. That came out at just over 2 degrees as well.

We placed the jack under the front of the differential and jacked it until the pinion angle went to 0 degrees - the springs took it up easily. I thought I would have to loosen the U bolts (axle to springs) but it wasn't necessary.

Then we ran the drive system up to about 50km/h, noted the vibration (which I had hoped would be gone) and slowly released the jack - no change.
It was the same at 100km/h. Laurel thought it was a bit better but I was going for complete cure.

My next guess is the pinion bearing (somewhere in the middle of the night this occured to me). I quickly crawled under the car this morning and tried to give the pinion bearing a rattle - I grabbed the diff flange and wobbled it up and down with all my strength.
It felt totally secure - no give at all.

I'm now at the stage where I'm ready to find a good drive shaft specialist and give them the problem.

Issues to Resolve - not quite finished

A number of people have congratulated me on finished the Vogue. Getting Vic Roads approval was a goal but unfortunately isn't the end of the project.
Back at the end of 2012 this ended one of my posts:
"My target for the moment is VicRoads approval so everything else can wait. I pick up the polycarbonate partition for the boot tomorrow and I'll be preparing the car for inspection over the Christmas to new Year break."

So now it's approved but not quite finished.
Known issues:

1. Tailshaft speed vibration - I suspect differential pinion angle. This is the big one and stops me driving it too much until it's sorted.
2. Brake master cylinder. Pedal is not returning fully. Not a big issue but indicative of a problem. I have a spare (I think) so I'll restore that and do a changeover. We caused this when we flushed through new brake fluid - a common problem in cars that haven't been driven in a while.
3. Winding window outside weatherstrips. I need to dis-assemble all doors and replace the clips - they're falling off inside the doors. Getting the correct clips is a pain as the originals don't fit due to a difference in the weatherstrip. (I kind of knew I had a problem when I fitted them then warned the family not to wind the windows all the way down.)
4. Slight "thump" when starting from stationary. This is a controller programming issue. It's fine going on and off regen when actually moving - it's just when starting. Annoying.
5. Front end work. Knox Tyrepower noted that while most of the front end was fine, there are a couple of bushes that need replacing. While at it, I'd like to get prices on lowering the front about 20 to 25mm.
6. Remove and modify all 12 chargers. I am not at all happy with how they balance the packs at the end of charge. I have modified one of my spares and it worked well so I now need to remove, modify and replace all chargers. The rear ones are easy - the front not so. While I am at it I am going to replace all M4 nuts and bolts on the front controller tray with rivnuts so I can get individual items off the tray without having to remove the tray as I have to now.
7. Front parcel shelf (below the dash). Laurel wants it back in. It doesn't really exist anymore as it was a total wreck. I kept the metal front though.
8. Car Radio and speakers. Also mounting for the little Lenze (motor controller) keypad and display.
9. The "other" controller - the 75kW version. I have all the parts for the upgrade but it's pretty low down on the priority list. Unfortunate, as more power would be nice.

There is other stuff but they are the main issues.
We are renovating my daughter's bedroom while she is away for the next two weeks so the Vogue fixups will wait until that's done.