Wednesday, May 28, 2008

Motor Adapter, and a Problem

On Monday, KatC and I worked on the motor adapter. First, we built a wheeled dolly as a work platform for the 100+ kilogram motor, and clamped the motor to it:

Next, we put the motor adapter ring on - the bolts will get torqued to 35 ft-lbs:

Next comes the profile plate - again, torqued to 35 ft-lbs:

And finally, the flywheel is attached to the hub - the hub is not tightened down yet, since we will need to adjust the flywheel-to-profile-plate distance.

The next step is to adjust the distance. Unfortunately, the closest we can get the flywheel to the profile plate is 1.62", which is 2/10" farther than the required 1.415" +/- 0.01". This is due to the fact that the splines on the shaft do not extend all the way to the motor, and this is as far back as the splined bushing can slide. I've sent email to Electro Auto to ask about options; as I see it, there are three main ones:
  • Add a 2/10" thick spacer ring between the motor ring and the profile plate
  • Machine the tapered bushing down so that it can slide farther back on the shaft
  • Add a 2/10" thick large metal gasket between the adapter plate and the transmission bellhousing
Doing nothing is not an option - 2/10" is plenty to interfere with the normal operation of the clutch / flywheel combo. I prefer the spacer ring because I think it will be the optimal cost / effectiveness option. But I'll wait and see what EA has to say before I take action.


rheuckeroth said...

If Electro Automotive does not have a resolve this problem I may be able to help. I have a CNC plasma-cutter and plent of scrap 1/4" aluminum sheet. If you provide an CAD drawing of the shim plate you need I could cut one out for you. The 1/4" would bring the profile plate out farther than needed, so you would have to adjust the taperlock hub/bushing out by 0.045". I would do this for you at no charge. I like what your doing and appreciate the blog. Let me know

Ross Cunniff said...

Thanks. EA has offered to fix the hub / bearing, which sounds like the best option to me.

Anonymous said...

Did you send Mike the magic number of 0.85 or 1.415?
Matt Kramp

Ross Cunniff said...

Actually, EA already had measurements from another Cherokee they had done. The 1.415 number came from them (and is clearly the distance to the front of the flywheel).

Anonymous said...


I was just reading your story about the Jeep Cherokee EV conversion and I am thinking of doing a similar conversion on my 1997 Jeep Wrangler. Any progress since May? So any updates on your projected speed or range? Anything you would do different if you were going to do it over again?


Mark Collette
Stafford, VA

Ross Cunniff said...

There has not been a lot of work done in the past few weeks due to my work schedule. However, I'm planning on taking the first week of July off to work on the Jeep, so I hope that things will pick up.

At this point, the only thing I would do differently is the charger / regulater - mostly because they still have not been delivered.

Anonymous said...

Came across your blog and very interested to follow and ask some questions if you dont mind.
How did you come to choose this motor and this voltage and number of batteries. I have a 93 and was thinking of a conversion. Thanks, Joe

Ross Cunniff said...

Joe, good questions. A little of the answer can be found on this earlier post. But I had several email exchanges with Azure Dynamics before I settled on the AC55.

I was toying briefly with the idea of using the AC24 (or its sibling the AC24LS) along with the AT1200 gearbox, eliminating the transmission. However, there were several issues with that. First, the gearbox is designed for transverse installation with half-axles attaching directly to the wheels. It is theoretically possible to drive only one side of the gearbox (and therefore drive a driveshaft to the rear wheels) but that was difficult, and could wreck the gearbox.

Additionally, some calculations of torque / HP / etc. showed that trying to do direct drive would have yielded a very sluggish vehicle (particularly with 1500 pounds of lead-acid batteries installed).

The paper specs of the AC55 line up well with the specs of the Cherokee - it's a little overpowered (it claims to handle vehicles from 5,000 to 11,000 lbs GVW - the Cherokee will come in at around 4,500) but I suspect that I will like the extra power when accelerating.

With the motor and controller chosen, the voltage was pretty much a given - the nominal specs for the AC55/DMOC445 combo call for the 312V system. This means 26 12-volt batteries (assuming you're not going with pricey exotics like LiIon or NiMH). With that many batteries, sealed is a necessity. So it became a search for the best compromise between capacity (Ah) and weight and size (given that I have to stuff 26 of these in somewhere).

With all that taken into consideration, the Concorde battery seems to meet my needs the best.

I'll try to document all these tradeoffs when the project is done and I make the "summary" post.

chetan said...


Kevin Johnson said...

Would it be possible to get a copy of your 2D drawing for the adapter plate. I just bought a AC55 and want to start the design of my own, but can't find drawings that show the exact locations of the mounting screws on the front of the motor.

I am converting a 95 Camaro (not the most practical but should be fun).


Ross Cunniff said...


Since I purchased the profile plate from Electro Automotive, I do not have detailed measurements of bolt hole / locator hole locations.

However, if I ever drop the motor again, I'll be sure to take them and post them.