Tailshaft and Coupler at the Balancer

The tailshaft (driveshaft) and motor coupler are out of the car again and at the balancers.
They are going to thoroughly check out the mating between the two and balance them as a set.

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.

Motor Coupler "nipped up".

One of the things on my to-do list was to tighten the M12 bolt that holds the motor coupler to the 38mm motor shaft (after it had been taken off then put back on again). I was reticent to use anything that would scratch the nice red paint job on the coupler.

So last night we fired up the controller, reduced the maximum RPM to around 50 RPM and I put a torque wrench on the bolt while William (13 yr old son) pressed the accelerator until I said "STOP" - at around 70NM.

Ya gotta love motors that develop torque at 0 RPM.
Sorry, no pictures, I was a tad busy and it was too cold under the car to do a set-up shot.


I also wasted some time copying the front footwell trim cardboard to corflute to find out the fit was terrible (the original was the problem).

The blue is what I cut away to make it fit and the red is what I have to add.

I'll do them again.

Motor Coupler

The motor coupler sits between the motor's 38mm shaft and the front drive shaft flange. It was mild steel so had to be painted. I chose red. I figure you have to crawl under the car to see it so I'd make it easy to spot.

Motor Coupler and Unicorns

I took this picture at the same time as the ones with the coupler on the motor.
When someone at work saw it they said I should post it. The Unicorn sheet is covering the floor of the car while we mess with the headlining (to ensure it stays clean - the headlining, not the floor).
Remarks about magical Unicorns and Electric Cars were rife when it was spotted
You might notice it looks slightly shorter than the other photo. It is - by about 5mm. The 38mm bore was the same length as the protruding end of the motor shaft and it would have hit the bearing casing. Better safe...

Motor Coupler and Driveshaft

Back at the start of this year I sought out a few companies that did drive shafts (tail shafts) in my area of Melbourne. I kind of knew what I wanted to do, but not really how to go about it. Basically I knew I needed a sliding spline on the motor end of the drive shaft and I would have to get my old one extended by about 200mm.

The third company I rang didn't balk at all at the mention of a 3 phase motor in a car (the others did!) and were amazing helpful straight away in that they could make the coupler (38mm motor shaft to flange) and the drive shaft to match. I have found Jeff, Russell (now left) and Graeme a delight to deal with at Precision Balancing in Ferntree Gully.
Anyway - to the point. I contacted them again at the start of September and dropped my old tail drive shaft in mid September.
The coupler was ready last week.

I finally got to remove that blue insulation tape from the motor shaft. I cleaned it with enamel thinners to de-sticky it.

After some minor tweeks the coupler slid smoothly onto the motor shaft.

I have measured the motor flange to differential flange dimension and given it to the guys. Drive shaft next.
It will look something like this one.
The left hand end connects to the motor coupler flange.

Meanwhile, I pulled the headliner out again last night for some slight changes - nothing major. We should get it back in (for good) on the weekend.