CitiCar RebornBy Andrew Letton
Reprinted with the author's permission.
As I've mentioned before, I am in the process of rebuilding a '76 CitiCar. I know I enjoy reading of others' projects, so I thought I'd make my contribution to the list. If this isn't your cup o' tea, delete away...
Part 1: Where it sat for about a year...
I got a call from my friend Devon some time in early '94 telling me that he had seen an ad in the local paper for a CitiCar for sale for $400. Devon was in the process of converting a Rabbit, so wasn't interested in it himself. I couldn't afford it at the time, but I passed the word on to Otmar, thinking he might know someone who was interested. It turns out that Ot considered buying it himself; he went so far as to drive over the hill to Santa Cruz with a trailer to pick it up, but when he saw its condition, he decided against it. The batteries were toast, and the body looked like it had been used for target practice by some little league pitcher. It had two major holes in the front of the plastic body and several other minor holes and cracks.
I don't remember exactly how it happened, but a few weeks later, I got word that the price had been dropped to $250. At that price, I had to at least take a look! I figured that the motor and charger were probably worth that, even if I scrapped everything else. So I hitched my 4x8 foot flatbed trailer to the back of my 3-cyl Chevy Sprint (I know you're laughing now! But hey, it works! :-) and headed over the hill to Santa Cruz. As Ot said, the car was in pretty bad shape, but I decided to buy it anyway; after all, I was bored and didn't have any other projects going... NOT! ;-)
After a thoroughly uneventful trip over the mountain on highway 17 with the (batteryless) CitiCar on my trailer (I got more than a few wide-eyed stares!), I parked it at my shop in Livermore, where it sat for about a year. Then I got a job near Santa Cruz, so I towed it back over the hill and parked it in a warehouse at work, where it sat for about a year. Then I got a different job moved the CitiCar again, where it sat for about a year... You get the picture. I didn't have the time or money to do anything with it.
About a year ago, I was finally in a position where I did have some time and a bit of $$ to spare, so I started repairing the body and gathering parts. I bought a used Curtis 1209 controller and Vicor DC-DC converters from Lee Hart, a used Albright emergency disconnect switch from the bargain shelf at Wilde Evolutions' booth at the Phoenix races, current shunts from the local electronic surplus place, and a $75 set of 4 new tires from Sears (thanks to someone here on the list who mentioned Sears' $15.99 145R-12's). I picked up a gallon of resin and some fiberglass cloth from the local boat builder supply and started getting sticky. The previous owner had gathered and saved pieces of plastic which had been broken out of the car body. After gathering the ones which came in a plastic bag with the car and the ones I could find under the "hood", I had a box of probably 75 pieces of plastic, ranging in size from 1/2" to 3". Truly a jigsaw puzzle of challenging proportions, considering that they were all the same color, and there were a lot more 1/2" pieces than 3" pieces. With a bottle of cyanoacrylate (sp?) super glue designed for plastic, I slowly pieced back together the front of the CitiCar. After many hours of gluing my fingers together, I was able to place all of the pieces and found that there were only three holes, each about two square inches, for which I didn't have plastic chips. Since the plan was to cover the patched areas with fiberglass, I simply filled these holes with cut pieces of posterboard. After a bit of spot putty and sanding, I put two layers of 10 oz. fiberglass cloth over the jigsaw puzzles. With some white pigment in the final coat of resin, the patches were difficult to see... as long as you were standing 50' away, at dusk, wearing sunglasses! :-) OK, it's not pretty, but my main goal was simply to keep the rain out, and the fiberglass did that.
And then it sat for about a year...
Part 2: Copper, aluminum, and silver.
I work for a Silicon Valley startup, and in 1996, we all worked right through most of the holidays. This past year, we released our product and it is doing well, so our president decreed that the company would shut down from before Christmas until January 5th. After Christmas with my family, I finally got the chance to get back to the CitiCar.
With the bodywork mostly finished, I turned my attention to the electrical system. I started by removing all of the high power electrical system. I found several battery and motor cables with charred insulation near the ends and a set of contactors with some severely melted contacts. The stock Lester charger had sadly been located directly beneath one of the largest holes in the front of the body, and had been rained on for years, so I was concerned for its condition. When I examined the motor, I found that the one terminal (A2) which was not in plain view when looking under the car had, at some point in its life, gotten quite hot, causing a melted feed through insulator, which in turn allowed the stud to short against the motor case, melting some of the aluminum! Isn't it always the way it goes -- the deeper you dig in to a project, the worse it gets.
I figured that it would be helpful to have 48V for testing things as I put them together. Otmar had a pile of "dead" batteries which he had removed from his truck but not yet gotten rid of, so I went over to Palo Alto and picked the best 8 to put in the CitiCar. After cleaning out the battery box and cleaning and watering the batteries, I installed them and looked to the charger. Of course I started by simply plugging it in to AC (wishful thinking!). The thing buzzed so loudly that I instantly unplugged it. After I got my courage up again I plugged it back in and noticed that most of the noise was actually coming from the charge interlock relay bolted to the back of the charger. I couldn't figure out why it was oscillating, so I unplugged it. After that, I heard a normal faint transformer buzz, but got no DC output. :-( I opened the case and studied the wiring. After tracing out the circuit, I found that the output leads from the transformer headed towards the rectifier diodes, but ended about 1/4" shy of the diodes. Apparently, the galvanic action between the copper diode leads and the steel/zinc bolt holding the ring terminals together had caused the leads to _completely_ corrode away. So where does one find 25+ amp diodes on a Sunday morning? Even here in Silicon Valley, Sunday is Sunday and Fry's doesn't carry diodes that big. I got on the phone; "EVCL, this is Otmar". Once again, Ot came to my rescue. He had the diodes I needed in his junk bin, and they were even already mounted to a heatsink. By the end of the day, I had the new diodes installed in the charger and the batteries were happily bubbling.
I pulled the motor from the axle and opened it up on the bench. It turned out that a solder joint between the A2 stud and the brush carrier had broken. I'm guessing that it got over-torqued at some point. The high resistance of the broken joint probably caused the heat which melted the feed through spacer which caused the short to the case which melted the aluminum! Luckily the car came with an extra brush carrier for the motor, complete with feed through spacers, so with that and some JB Weld to fix the case, I reassembled the motor. I hooked up my 12V battery charger, and it spun up nicely. Just for fun, I let it run for 5 or 10 minutes. When I shut it down, I found that the output shaft was HOT! I had checked the bearings while the motor was apart, and they seemed fine, but I had heard an occasional "peep" from the motor while it was running, so I decided to replace the bearings. $28 and two trips to the bearing store later (I initially thought that the bearings were the same on both ends of the shaft. Oops.) I had what I thought was a good-as-new motor. I once again bench tested it for about 5 minutes and was astonished to find that the shaft still got hot! Suddenly it dawned on me what I had done. This particular GE motor has a separate rubber oil seal on the shaft, outside the bearing. In the course of replacing the bearings, I had thoroughly cleaned the motor as well. When I reassembled it, I foolishly did not re-grease the output shaft seal. I'm lucky I didn't burn it up! A little lubrication, and the motor was ready for reinstallation. I don't know about your projects, but I can never work on a project until it is completely finished and then throw the switch. No, I have to hook things up temporarily and test them out along the way. So that is just what I did with the motor. I jacked up the rear end and put it on jackstands, then I got out a pile of 12ga. alligator clip leads and hooked up the controller and motor. After opening up the rear brakes to free a stuck parking brake, I put power to the motor and spun the wheels. Hey, this is fun!
When new, early CitiCars were sold with a 3-speed contactor controller, consisting of a forward/reverse DPDT-center off contactor, a DPDT contactor which put the two 24V battery banks in series or parallel, and a SPST contactor which switched a resistor in and out of the circuit. While there is something to be said for the simplicity and efficiency of a contactor controller, one of the down sides in the serious abuse to the contactors. Switching them under load does not make the little silver contacts very happy, and this was obvious on my F/R contactor. Several of the 16 silver contacts in the contactor were quite pitted and one was almost completely melted away. Thanks again to some past owner of the car, it came with a bag of spare contactor parts, including the contacts, spacers, and insulators I needed to rebuild the contactor. I took all of the copper parts to a wire brush mounted in my drill motor, and when I got it all back together, the contactor looked brand new.
Andrew "Midnight" Letton San Jose, CA