Thursday, April 29, 2010


I put the car up on jack stands yesterday and began disassembling it this morning. So far so good, but it's been very slow going. I'm not sure if I should be proud of how well built and how secure everything is, or ashamed it takes so much work to take it all apart. I used to curse engineers that made working on cars this difficult. But then I'm not an engineer, so I guess some slack is in order.

The batteries are out of the first two trays. Later I'll tackle the back box.

I received some encouraging words from George Hamstra at NetGain Motors. I wrote to tell him of the vibrations and that I'm taking the car apart to fix it. I'm worried that the motor may be damaged, which is causing the vibration, or that the out of balance clutch assembly might have damaged the motor. He said that it was highly unlikely that the motor was damaged, especially if I caught it in time. I'd put less than 100 miles on the car since I first noticed it, so I think I should be good. As soon as it's out, I'll test it and report back.

I'm thinking the reason it's gotten worse is likely due to the failure of the pilot bearing that's seated in the hub assembly couples with the transmission shaft. It was new when I put it in and probably helped to mask or limit the vibration. But I'll know more when it's out and I can see.

One thing I haven't mentioned is that I'm going to take this opportunity to improve the car a bit. I'm going to redo the lay out of the batteries in the front end. When I decided to go with lithium cells, I'd already designed and built all the supports for the lead acid. I had figured there was no need to redo the existing supports, so I worked to get the lithium cells to fit into what was already there.

Later I realized the mistake I'd made, it posed two problems. First, there is some debate as to the proper way to orient the batteries. People weigh it on both sides. Some say that you can orient them anyway you'd like and it won't harm them, while others say you MUST keep them upright. The truth is that no one knows for sure. But there is one certainty, and that is the manufacturer says they should be mounted upright. I haven't seen any elaboration on why, but if they say it, that's good enough for me.

The second reason is ease of accessibility. Every month (twice) I'd do some basic maintenance on the car, checking for loose nuts and bolts, and making sure there were no other problems. I'd also tighten all the bolts securing the copper straps that connect all the batteries. You'd be surprised how much they can loosen up in that time. Well, I'd check all but about 7. There were 7 I simply couldn't get a wrench on. I realized early on that this was bad and that I'd have to do something about it. So now I get the chance to do just that.

I think I've figured out a lay out that will accommodate all the batteries in the engine bay, let me get to all the things I need to get to and still let me shut the hood. There will be much more on this as I progress.

Monday, April 26, 2010

Bad News Everyone

I'm afraid I have no good tidings today. Let me get straight to the meat of the story.

Last Sunday, I left the house in the Z3 with the usual EV grin on my face. A few houses down I noticed a slight vibration through my hand resting on the gear shift. I thought "Hang on, I don't remember this." But it was slight and I hoped it was my imagination. Well over the next few days I realized that not only was it NOT my imagination, but it was getting steadily worse.

Of course, I immediately went into trouble shooting mode. Ultimately I was stopped on the side of the road, with the car in neutral, carefully revving the motor. Sure enough, the vibration started up at about 2000 RPM. It was worse at about 2500 RPM, and then seemed to start abating, but it did not go away entirely. Since I was sitting still, that rules out the possibility that the imbalance lies in the transmission or beyond in the drive line or wheels. It is in the motor and clutch assembly.

I pushed the clutch in, held it and revved again, same thing. That test ruled out the clutch disk since it wasn't spinning with the motor at that point. The vibration was still present. That leads to the following conclusion. One of the following things has managed to fall out of balance: the motor, the flywheel or the clutch plate.

I find it hard to believe that a solid hunk of aluminum has somehow gone out of balance, so I think it's safe to rule out the flywheel. That leaves the motor or the clutch plate. Unfortunately, each of those seems as unlikely as the next, but there's no getting around the fact that one of them has gone out of balance.

So, what next? Well, I can't leave it this way. I noticed it getting worse in only 4 days and about 100 miles. There's no way it's going away. It will only get worse, do more damage and get more costly to fix. I'm going to have to pull the motor and transmission assembly, dis-assemble it and find out who the culprit is.

So there you have it. Hopefully I won't be out of commission too long. I had to drive my old ICE Passat this past weekend. I definitely miss the EV grin. Please feel free to leave your condolences.

Tuesday, April 20, 2010


Well, it's become clear that I have to get new springs for the front end of the car. The other day I went over a speed bump and it bottomed out on the way down. Ouch.

I measured the ride height of the car before I started the project, and I also had it weighed (as you may remember). After the conversion was complete, I measured the ride height again and found that it was riding 3/4 of an inch lower than before. I started looking into different springs available for the car and found that they were all designed to lower the ride. Most by an inch or more. With that in mind, I was perfectly happy with the 3/4" I was seeing.

But then I started looking through the service manual and found out how BMW measures the ride height. It also listed what the ride height should be. I measured it the way they recommend and found that it was over 1.5 inches lower. Now my original measurement wasn't off, so that can only mean one thing, the car was already 3/4 of an inch lower than stock before I started. I haven't pulled the car apart yet to verify that there were already aftermarket springs on the struts, but that's my suspicion.

Oddly enough, the ride on the rear end of the car is at factory spec. Huh... strange.

Well any way, when it bottomed out the other day, I decided I need to do something about it. My neighbor had suggested looking at other BMW's to find out if there was a chassis that used the same spring with a different rating. Great idea! So, this is an E-36 chassis, and the good news is that there are several other models and years built on the E-36 chassis. The bad news is that there were only two heavier than mine, and they were only 100 lbs heavier. So, scrap that idea, that's not close enough to the 386 lbs the car gained.

I've read on the EV Discussion list that most any city has a place that specializes in building springs. Frequented by off-roaders and truckers, these places can take an existing spring and fabricate a replacement the same size but with a different rating. I asked my cousin Tommy (who is in the heavy truck business) if he knew of such a place. He said he didn't, but asked a local shop that sells springs. They had said they could send it out of state, but that they didn't know of a local place either.

So, I'll spend some time tapping into the off-road shops around town and see if they have a suggestion. If not, I guess I'll be sending my springs out of town. Of course, if the springs on the car are aftermarket springs, I'm going to have to get a hold of a stock one that I can send instead. That might be better because then I don't have to disable my car for the several weeks it will take to get the new ones.

Friday, April 16, 2010

Vacuum Issues

While it's true that nature abhors a vacuum, nature has nothing on how much I abhor the vacuum brake system on the car. It turns an otherwise lovely quiet experience into a nerve shattering episode every time it kicks on. Part of that is my fault because I opted for pump I found on eBay for $90 instead of going for a quieter one from one of many EV component dealers. My efforts to deaden some of the noise it makes fell short.

But that's not what this post is about. I haven't posted much about this because I really haven't had a handle on what the issue was. Early on I noticed some erratic behavior from the system. It would refuse to come on, stay on too long, not turn off at all, turn off and I'd have no vacuum assist on the breaks or stay on and I'd lose vacuum assist with the brakes. I can tell you when that pump simply won't shut off, it sucks most all of the joy right out of my drive. As far as problems with that system are concerned, you name it and I've experienced it.

At first I thought that the vacuum pressure switch on the reservoir was bad, but ruled that out because I found a leak. I fixed the leak and the problem went away. Until one day the pump came on, pumped the system down and turned off and I found I had no vacuum assist. At that point, I was certain that the cause was a faulty check valve, so I ordered a couple replacements and some fittings to see if I could fix the problem. The check valve that came with the reservoir is kind of sloppy. It works, but you can suck a fair amount of air through it before it engages. As it turns out, that's really how it should work because a new one that allows for none of that play didn't work at all. It sealed off immediately and allowed no vacuum to the brake drum at all.

Well, after 4 more weeks and a number of episodes which I won't bore you with, I think I may have finally figured it out. I borrowed a hand held vacuum pump from a friend so that I could draw a vacuum on different parts of the system to see how things behave. I was hoping to find where the problem really is. I pulled into my driveway the other day and the pump was running non stop, and the brakes were working fine. I popped the hood thinking I'd pull the line out of the reservoir I installed that runs to the car's vacuum assist drum. I wanted to seal the canister with my finger to see if the pump drew a vacuum like it's supposed to and if the switch turned the pump off eventually. Well, I inadvertently flicked the vacuum pressure switch with my finger and the pump shut off.

Since then I've had the pump come on and refuse to come off on two occasions, only to find a quick tap on the switch causes it to trip and turn the pump on. After which it runs normally again. Now, I haven't ruled out a problem with car's brake assist drum, but this is certainly headway.

The switch has a screw that allows you to adjust the vacuum up or down depending your needs. I think I'll play with that a bit to see if it helps. If not, it looks like I'll be ordering a new switch. Eventually I want to replace the pump with a quieter one. They range in price from $250 to $400 for the real quiet ones. It's not the money at this point that's holding me back. It's the prospect of having to put the car back up on jack stands to incorporate the new pump into the existing system. It would require quite a bit of work. I guess I love driving it more than I hate the pump.

Monday, April 12, 2010


The last couple weeks have been pretty busy. I'm surprised at how many people have emailed after having seen the car on Jack Rickard's Friday video. So many positive comments and compliments. Why it's enough to give a guy a swelled head :-)

One of the first people to contact me was a local man by the name of Greg who has thought long and hard about converting a car. About three weeks prior to seeing the video, he'd come to the decision that the Z3 would be the car for him to convert. He was shocked to see a converted Z3 and floored that it was actually in the same town he lived in. Greg stopped over and I gave him a full tour of the car, answered all his questions as best I could and offered to help if he ever decides to try to pull it off. A great visit and I hope to stay in touch with him.

Today I was visited by one of the true stars in the EV world, and that was George Hamstra. George works for Netgain motors the makers of the WarP series motors and of course, the motor in my Z3. An icon in the EV motor world. He was in town with some friends enjoying the fantastic Spring weather here in Arizona, and took the opportunity to stop by and see the car.

What a great time. Lots of questions, laughs and pictures! I gave George and both his friends, Charlie and Terry, rides in the car and everyone had a great time. For Charlie and Terry, it was a first time for each of them in an EV. They were reluctant to go for a ride at first, just being polite I think, and trying not to imposed. But once I coaxed them into the car, they really enjoyed it. That's always the case with anyone who rides in an electric car for the first time. That's what the call the EV grin.

It's been a real pleasure answering peoples emails and showing off the car to people that take the time to come by. I expect that things will begin to slow down now that the car isn't getting any new exposure, and that's certainly ok. But for all you faithful readers, remember, if you're ever in Chandler, and you'd like to meet up and go for a ride, let me know. It's a great community and I'm happy to be a part of it.

Thank you all.

Friday, April 2, 2010

On A/C and RPMs

On Monday I received the new beta exciter rings for the newer style RPM sensor. You may remember that the newer style RPM sensor mounts flush to the motor and would allow me to use the remaining portion of the tail shaft on the motor to mount a pulley I can use for the A/C system.

I got to work putting the new sensor in place so that I could run some tests and get some comparison numbers. I thought I'd get a new set of numbers using the old sensor first, and then switch the leads connected to the Zilla to the new sensor and test it. Last time I got readings in first gear at 10, 15, 20 and 25 mph. I wanted to do the same thing this time, but add tests in 2nd and 3rd just to get more data.

Sadly that wasn't to be. When I was putting on the new exciter ring, I knocked the cup for the old sensor that fits over the end of the tail shaft out of alignment, and didn't notice. When I went out to test, I watched the RPMs climb to about 1600 and then the tach went dead. When I got it back in the garage, I found that the magnet inside the cup had been rubbing on the side of the cup and self destructed. *Sigh*

So I took it off and started the test on the new sensor with the new ring to get some new data. Since I had the old data from the older style sensor, I could still compare those two sets. What I found was a slight deviation. At 25 mph, the old sensor reported 4300 RPM, but the new one reports 4600 RPM.

Working with the manufacturer and Ryan at EV Source, we decided to crunch some numbers to see what it really should be. Based on the size of the tires and the final drive ratio in 1st gear, the RPMs at 15 mph should be 2632. The sensor is reporting 2600. I'd say the new sensor is more accurate than the old one.

I took off the old assembly I'd built which was designed to hold both sensors in place, and mounted up the new one. Then I mounted the pulley. I don't have a belt for it yet, so I need to get that next. Then I need to take it down to an A/C shop and find out if they can build new lines for it, and more importantly, if they are willing to. I'm really worried they'll take one look under the hood and say "No way!" In any case, I'm one step closer to A/C.

Thursday, April 1, 2010

So How Fast is This Thing?

Most of you are aware of the difficulties I had with the car regarding acceleration early on, and how it was my own dang fault. And most of you are aware that problem has been sorted. Which probably means most of you are wondering when I'm going to post some 0 to 60 times and what not. Here's the full story.

Right now I have the Zilla set to only draw no more than 500 amps from the batteries. The batteries voltage is 160, so that works out to 80,000 Watts. Netgain recommends that you push no more than 170 volts to the motor, and as you probably know, the Zilla can put out a maximum of 1000 amps. That means that the most power I can theoretically send to the motor is 170,000 Watts. So, as the system is configured right now, I'm allowing just under half the power possible to go to the motor.

"Why" you ask? That's a good question for which I have a couple of lame reasons. First, the Link 10 meter I have can accurately read only 500 amps. If I pull more than that, it won't hurt the meter, it just won't read it accurately. So that's not really a problem as long as I don't put myself in a situation where I need to rely on the meter to determine how much energy I've drawn from the pack. I don't want to run the pack dead and destroy the batteries. Second is that I just want to spend some time breaking the batteries in under less than full stress conditions. I don't know if this is completely necessary, but I seem to remember reading somewhere that treating them kindly the first 75 cycles can add to their longevity.

The bottom line is that I do intend to ramp it up at some point in the future, just not yet. I likely wont' leave it there, but I'll do it just long enough to get some readings and have some fun. I was thinking mid April.

Right now the car does 0-40 faster than stock. It really sets you back in your seat. Above 40 though, the acceleration begins to fall off. It reaches 60 in about 10 to 12 seconds which is higher than the stock 7 seconds, but certainly acceptable for everyday use. I've reached 80 on the freeway, and the car was still pulling. I can easily spin the tires in first gear, and the tires chirp in a hard start from second. There's no question that there's a beast under the hood, it's just leashed at the moment.