Seating New Brushes

You're probably familiar with the problem I've been facing recently regarding the leak to chassis ground through the motor.  It's proven to be a very strange problem. I made a quick video to demonstrate what I'm seeing, take a look.

A leak at 635 Ohms and 160 volts equates to 252 milliamps.  The 436 Ohms I read the following day would produce a current leak of 367 milliamps.  I've seen the reading as high as 1180 Ohms, and as low as 350 Ohms.  This sort of leak is most often caused by the accumulation of dust in the motor.  I've blown enough air through the motor that if that were indeed the problem, it should have fixed it.  But as you all know it hasn't, so George Hamstra has decided he's seen me suffer enough at the hands of this motor, so he's sent me a new one.

 Since that picture was taken, I've pulled the clutch assembly, flywheel, adaptor plate and taper-lock hub assembly off the old motor with the help of my friend Dave from Tucson.  However, I haven't put it on the new motor yet.  In email exchanges with George, I mentioned that I would be sending back the $320 brushes he sent me (at his expense) to try to resolve the problem with the original motor.  But he replied saying instead that I should put them in the new motor.  He believed that the brushes in the new motor were likely brushes better suited for racing.  I peered in the motor and found they were the Helwig Redtop brushes, but when I compared them to the ones George had sent me I could see a marked difference.  They were a bit shorter, but much darker in color.

So at George's recommendation, I swapped them out.  But that means I need to seat, or bed in the new brushes before I put the motor in the car.  Essentially, you strap the motor down, and connect it to a 12v battery and let it spin for 100+ hours.  It sounds easy enough, but actually getting it done required some effort.

First I needed a 12 battery.  I don't have one laying around, so I went to the local Costco and bought the cheapest 12v deep cycle battery they had for about $80.  I was under the impression that the motor would draw about 3 to 5 amps, once it had spun up and was running smoothly.  So I thought my little 0-12 amp battery charger could keep up.  Well, that was off by a factor of 10.  It actually draws about 45 amps at start up and settles in to a constant draw of about 35 amps.  Fortunately a friend at work was kind enough to lend me his heavy duty charger that can put out up to 200 amps for starting a car, or as much as 40 amps for charging the battery.  Perfect!  Here's how the assembly looks.

At the top right, we have Fred's big charger.  Below and to the right, is the 12V battery.  I have both the cables to the motor hooked up to it, as well as the cables from the charger.  Notice on the negative line running to the motor is a big switch; a nice way of turning the motor on and off.  My meter is sitting on top of the battery with the probes connected to the terminals.  In the morning, I turn the motor on.  When I see the battery hit about 11.00 volts, I turn the charger on.  It operates by timer, so I set it for 2 hours.   It immediately pushes the voltage up to about 12.8 and puts out about 43 amps.  The motor is drawing about 35, so it's a net of about 8 amps going to the battery.  Over that two hours time, the voltage on the battery rises to about 13.5.  By the time the battery hits 13.7, the charger is putting about about 36 amps, or one amp more than the motor draws.  So I turn the charger off and let it rest.  (I don't want to burn it up.)  When the battery gets back down to 11V, the charger goes back on.  I'm on day 4 of the break in, and it's been running about 50 hours.  Since the charger is on a timer, I can't run the system at night.

When the brushes have had enough time to seat, I'll re-assemble the adaptor plate and clutch, then work to getting it back in the car.

A Great Video 

On an unrelated note, a PBS station back East, WSIU, has published a story about last Septembers EVCCON and EVTV.  The story is quite well done.  It explains what the movement is about, why people are doing it for themselves and why Jack and Brian are producing the weekly EVTV show.  It's about 1/2 hour long, and it's well worth watching.  While the Z3 is not featured in the video, you can see it in the background on a few shots.  Take a look:

Motor Pull

Funny, you usually see an entry in and EV blog called "Motor Pull" as one of the first entries. Certainly not one after the proud builder has put only 901 miles on the completed car!

OK, enough grousing. Here's the, once again, empty engine bay.

My dad was kind enough to come over and help me get the motor out of the engine bay. It was quick work. I had everything disconnected by 10:30 and we had the motor out 1/2 hour later.

The first order of business was to start testing. We pulled the transmission off of the adaptor plate to expose the clutch and flywheel. I secured the motor and we spun it up. Sure enough, there was the wobble. It took a while for the 12 volt battery to spin it fast enough to see the wobble, but it got us there.

Next, we took off the pressure plate. So only the fly wheel was mounted to the hub. We spun it up again and... wobble. OK, so now we can check off the pressure plate and clutch disk as the cause. Next we removed the flywheel, leaving only the motor and the hub.


We put the battery on it again and watched carefully. There was still a bit of wobble, but it was substantially less. Perhaps 85 to 90% of the wobble was gone with the flywheel off. So, here's the culprit:


I was kind of surprised to see that there was some wobble with the flywheel off. I did what George from Netgain suggested. I spun it up and looked straight down in the hub. There was no sign of movement at all. I held a piece of aluminum right next to the side of the hub as it spun to see if it rubbed periodically or consistently. There is no variation in the spin at all. Perhaps the slight wobble that we see is from a slight imbalance in the motor. All I know is that it is very minor and there is absolutely no play in the shaft or bearings, so I'm not going to worry about it.

Next I need to get that flywheel down to a shop that can balance it.

Transmission Arrives

Well, the transmission arrived today, as I'd hoped it would. It was in good condition with one minor exception, a guide plate that's bolted to it used for two hoses was bent. A couple careful whacks with a rubber mallet and it's good as new.

In the mean time, I needed to torque down the flywheel and attach the clutch and pressure plate. Realizing I needed to lock the flywheel in place, I started looking around for some way to do it. I ended up using a leftover piece of channel iron, a long bolt and a C clamp to hold the bolt down.

I realize this means I'm dangerously close to achieving the status of "redneck", but BMW wanted crazy money for the "official" tool. Anyway, here's a good picture of the whole assembly.



Next, I have to get some replacement hardware to bolt the tranny up to the motor assembly.

Adaptor Plate Mounted

This morning I attached the adaptor plate, taper-lock hub and flywheel to the electric motor. The tricky part was making sure that the distance from the friction surface on the new flywheel to the back of the adaptor plate was exactly the same as the distance from the back of the engine and the original flywheel. I took my time, was very careful, and got it right the first time. Believe me, I wasn't looking forward to the prospect of tying to get that taper-lock hub apart if I messed up.

Here's a shot of the beautiful WarP 11 motor. With the voltage I'm putting to it, it should develop approximately 220 ft/lbs of torque at 0 RPM. I'm going to have secure this to frame very well.

Next I mounted the adaptor ring, adaptor plate, and taper-lock hub. This required the most care, but really wasn't that bad.

Last, the flywheel goes on. What a stunner. 11 lbs. of sexiness, that's what that is!

Hopefully, the transmission arrives today. I need to get the hardware to mount it up to the motor, but once I get that taken car of, then the whole assembly goes into the car.

The Adaptor Plate Arrives!!

Well, it took way longer than I'd hoped and was promised, but it's here. Check out this aluminium loveliness.

Here's a close shot of the taper-lock hub that mounts to the output shaft of the motor. That is one fine piece of machining. Notice the little raised ring where the idle bearing for the transmission shaft will rest.

I still need to wait for the transmission to arrive. Probably tomorrow or Thursday. Then I can mount the whole thing up to the car. Before that though I can start working on getting the hub and plate mounted up to the motor. When I measured everything earlier, it looked like the Warp 11 motor should just fit over the subframe. Only installing it will tell.

More metal work

I admit I've been pretty bad about posting to the blog lately. There's only so many ways you can make working with steel sound exciting! I do have a couple things to report, so here goes...

1. I'm nearly done with the battery box and all the supports for the trunk space. The truth is, that I would have been done yesterday except when I went to bolt the whole thing into the car, I discovered that I'd drilled one of the pieces wrong. There was simply no way of recovering that piece, so I had to build a new one. I did that this morning and it currently has it's first coat of paint on it. Tomorrow, I should be able to get the piece onto the assembly and bolt the whole thing up to the car.

2. I finally got word from Electro Automotive that they've finished the adaptor plate. The transmission and the other parts are on their way home, albeit 5 weeks later than promised, but who's counting. Man, did that hold me up. Once that's bolted in place, I can get the motor mounts taken care of. Then it's just a domino effect clearing the way to do all the other mechanical stuff I've been held up on.

Pictures of the completed back battery box tomorrow. Hmm, that sounds dangerously close to a commitment.

Brown Disappoints

Early last week the transmission arrived at the shop that I've hired to build the adaptor plate and mounting hub. In spite of the fact that we used the paper from 10 hectares of forest packing it into that box so that it was immobile, UPS managed to inflict a bit of bad. You can see one of the eyelets along the bell housing was broken off. The machinist at the shop said that it would not effect the adaptor plate, so that was good news. I looked at the photo closely and began to think "I don't remember an eyelet in that location." I looked at the service manual and sure enough, I found that it was the location of a locating pin used simply to help you hold the tranny to the motor in the right place as you bolt it on. Sweet! Absolutely no impact. Big sigh of relief.

Packing the transmission

My daughter Emily was kind enough to help me wad up a forest's worth of newsprint and cram it in the box I used to send the transmission off. Why send it off, you ask? Well I couldn't find a local shop with experience making the adaptor plate and taperlock hub to mount the motor to the transmission. In six to eight weeks, it should come back ready to mount to the car.