Bolted On: The Art of Connecting Motors to Cars

I'm thoroughly enjoying the CAN/Arduino aspects of EVTV these days.  I can quickly edit a source file and compile it to a small Arduino board in about 20 seconds from any  Mac OSX machine in the shop or at home.  I can e-mail those files to myself or thumbdrive em to get back and forth.  In short, I'm in my element.  It all makes sense to me and even has a sort of sense of order that brings a calm to an otherwise chaos enfolded existence.

But from our first EV build, I have been mystified by the simple act of connecting an electric motor to a car. And to this day, contemplating any build causes a little anxiety level over just how we are going to connect THAT motor to THAT car.

It always works out.  Indeed, it always works out well.  We've never really had a problem with vibration or with it coming loose.  I guess the worst we've done was the Mini-Cooper and it really wasn't about mating the motor to the transmission.  The right hand half shaft had a bearing on it that was supposed to be supported by the engine, but we didn't have an engine.  We kind of fabbed up a sling around the motor with a holder for it, but the shaft kept popping out.  Finally solved it with a bit sturdier steel version.

The Mini Cooper sits idle today.  We blew up the DC-DC converter and possibly the Rhinehart controller we had adapted to the MES-DEA motor.  That system had actually worked pretty well, but contemplating fixing it now leads me to a lot of changes to the cooling system, the DC-DC converter of course, but if we are going to do all that, we might as well put in one of our Siemens or UQM power plants for a bit more power and all the configuration advantages of the GEVCU.  And so the repair becomes an upgrade and the upgrade almost goes to a reconversion and so the Mini Cooper sits.

Our first EV was a VW transmission in the replica 1957 Porsche Speedster.  We originally used a bulky cast aluminum adapter availabe from CanadianEV.  Later we replaced it with a bit sleeker version from Thunderstruck.  We liked the Coupler from Canadian EV and the adapter plate from Thunderstruck and eventually developed our own kind of combo.  Later EVNETICS came out with a really deluxe bling looking adapter for the VW and we ordered from them for several years.  Unfortunately, they are no more.

So it always gets worked out.  We even married a Husted twin 11 inch to the Escalade six speed transmission flex plate and somehow shimmed it in there where it worked perfectly. But almost always there are others involved in the actual design of the connection.

The truth is that I'm not at all mechanically inclined and indeed I'm baffled by the assembly instructions that come with a baseball bat.  We're trying to put a two post lift together in the shop right now and it is just mystifying to me.

In the past couple of years, we have been doing some great things I think with the Siemens and UQM motors.  Each have an identical 26 spline very short shaft on them designed to marry to an eGearDrive.  We had bought 16 of these drives at the Azure auction, and have since reordered in a minimum order quantity of 20 five or six times.  They've sold well.  But I confess I've never actually used one in anger or installed one on a car.

The nice thing about them is the UQM or Siemens motor just bolts right to it and the shaft is connected with an eggregiously simple 4 inch long "coupler" that simply fits over the motor shaft on one end and the gearbox input shaft on the other.  This makes the motor/car interface extremely simple.

Or does it?

Actually, it kind of moves the problem.  Now you have to have half shafts - axles to connect the gearbox OUTPUT to the wheels.  Another version of the same problem.

Please do NOT send me the dozen links you can easily find for people who make custom shafts.  They don't actually.  Yes, I know what the web site home page says.  They specifically TOUT their custom axle work in all cases.  But what we've found is that if you call them, they don't actually DO that anymore.  Too much work.  Easier to just ship off the shelf assemblies - you do have a part number don't you?  You DO know what you want to order don't you?

So when Brian Couchene offered to do a video on how to do all this, I jumped at it.  Indeed I could hardly wait to see it.  Perhaps it is again my mechanislexia.  But after watching it, I kind of had the idea that I had just watched him present a total of FOUR strategies he more or less guaranteed would NOT work to get you a shaft built???  Or???

Of course, for many cars you wouldn't use the gearbox but adapt the motor to the transmission.  Again, we had had EVNETICS do an adapter for us to mate the Siemens motor to a VW transmission.

We had a local machinist make us kind of a different version of that for the UQM to VW used in the Green Thing.  And so we kind of stumble along getting by from vehicle to vehicle.

We've kind of adapted a Matt Hauber design that Ed Clausen used on his BMW.  This is kind of a coupler "blank" that is a bit too small for the UQM or Siemens shaft.  You heat it up to 400 degrees F for an hour in an oven and then slide it on. When it cools, it shrinks and becomes rather tightly bound to the shaft.  We carry those in a three inch, four inch, and five inch diameter now.

Adapter plates are somewhat easier to design and build.  But again it is mechanical.

I've simply assumed that someone somewhere would set up an EV machine shop to do these sort of things.  But it really hasn't emerged.  There are just two many cars and too many configurations.  So I STILL contemplate any conversion with a certain amount of anxiety over the motor/machine interface.

One of our many sort of stalled projects here at EVTV is the Aristocraft boat.  I actually had some ideas originally about how to drive it.  But Jeff Southern, truly a master of machine work, offered to do it for us.  After having the boat nearly a year, he dropped it off at the shop a month or so ago untouched.  He just hadn't had time to do anything with it.  And so there it sits.

The Tesla Model S drive unit has been a kick.  I guess I suffer from a touch of Tesla Awe myself and expected to be at the CAN thing until the end of the year.  Basically we have it running from a $99 Arduino Due clone we make.  It just works.  I've got full control of the drive train and really quite good information from the inverter.  I have two strategies for a human interface - the EVIC and a new CAN switch module Collin found in Italy, but which is actually made here in the U.S., the Powerkey Pro 2400.

But it puts us right back with the eGearDrive axle problem.  We have to determine how to connect a shaft from the single speed gearbox to the wheels of car number whatever.  But unlike the Siemens and UQM, there is no good way to separate this highly integrated drive train into components.  You kind of have to use it as it is.  And that means an Independent Rear Suspension or IRS setup.

One viewer pointed us to Art Morrison Enterprises.  Again, this LOOKS like a custom suspension shop but it simply isn't.  They've got a few stock items, and you can have those in any color you like as long as it is shiny.  They actually make a kind of a generic IRS they call the multilink IRS.  But when we contacted them about adapting it to the Tesla drive unit, they immediately declined.  For $10,400 we can buy their off the shelf unit and do whatever we like with it.  And they basically stand behind their work.  They pretty much guarantee it will NOT work with whatever you want to use it for and you probably shouldn't be trying to do that anyway.

The salvage world is actually kind of strange.  We THINK we've bought a Tesla Drive unit with the complete rear clip - cradle and shafts and all.  But he isnt' going to ship it to us until the end of September.  That might give us some ideas.  One strategy is not to try to adapt the shafts to the wheels on the car, but replace the whole assembly and use the Tesla wheels.

The other sits right next to the Tesla Drive Unit Test Bench - the 1990 VW Vanagon pickup DoppelKabine we bought from Otmar a year or so ago.  We had several adventures painting this vehicle but finally got it covered in bright yellow plasti-dip.

The Vanagon is interesting in that it already has an IRS rear end.  More, the axles on this are very different.  Instead of terminating at the transmission with a splined shaft, it actually has a 100 mm flange with six bolts that bolts to a similar flange on the transmission.  It might be very easy to take the CV joints we have inserted into the drive unit on the bench, and kind of build them up to a similar 100mm flange and just bolt it together.  We'd have to take care to make sure it wound up being as thick as the transmission so the VW shafts would be the correct length, but it could be an easy fix.

I'm trying to picture how I feel about screaming down the road, seated right up in the extreme front of the vehicle just behind the windshield, with a Tesla Drive Unit accelerating me to just under the speed of light, with VW steering and a very high center of gravity.  But it would be one smokin DOKA.  And I wouldn't have to move the drive unit very far.

Fortunately, this all seems to be mostly a Jack problem.  We've sold a lot of Siemens and UQM motors and rarely even hear how they adapted them to the car.  Apparently with little difficulty.  And as I have said, we have sold a lot of eGearDrives, many without a motor at all, so that appears to offer a popular solution to something.

The weather has been just gorgeous here recently - we had a week in the high seventies with sunshine.  I've been driving the yellow thing, and I still don't get over it.  We did replace the shock absorbers on the left side.  I don't know why they went out with the shocks on the right side doing fine.  And indeed we repacked the grease in a CV joint in the right hand drive axle and that quited an annoying knocking sound.  But I truly never get over it.  Mathieur Rech contributed just a short video of his Toyota Land Cruiser padding about through the countryside in near silence.  And so it goes with my 1974 VW Thing.  It is just very quiet.  Squeeks from the seat springs.  Which appear to have some mysterious connection to the left side shock absorbers.  But that is all the noise it makes.  When it gets up to temperature a heat exchanger fan kicks in and provides a vague whir.  But I basically glide around Cape Girardeau in very near silence.  And I take unusually perfected joy in doing that.  Cars and trucks are roaring and snorting all around me, but my car just doesn't make any noise.

I've also become a huge fan of regenerative braking.  As we demonstrated rather empirically years ago, it doesn't add in efficiency to anything even approaching its reputation.  But it does FEEL good.  Both in the Model S and the Thing, it gives you a sense of total control with your big toe.  You can just make the car do anything you want almost by thinking about it.  And then it does it silently.  This is so very different from any pre-electric driving experience I ever had, that I just never do get over it.  It alters your senses and your sense of the road surface and what is going on around you.

Jack Rickard