EVDL Administrator via EV wrote: Alan Brinkman via EV wrote:
Some of the older Datsun mini-trucks had a rear axle ratio that would have the drive shaft spinning faster and some conversions did without the transmission. The few I looked at on the EV Album had a 4.88 rear end.
I also like the old Datsun mini-pickups. My first EV conversion was a 1974 Datsun pickup. It had a 4:88.1 differential as I recall. I used a surplus aircraft starter-generator as my motor. These tend to like high RPM, so this was a good ratio for it.
I kept the clutch and transmission. As it turned out, the clutch wasn't needed, as I mostly left it in 3rd gear all the time.
I don't know if this will help, but most of the Comuta-Cars used a 5.17 rear axle (Dana model 12). Some shipped to hilly regions had a 6.83 axle (Dana model 18).
For a direct drive on-road setup with a DC series motor, you will want something close to 5:1. That puts the motor RPM in a good range -- not so low that current is excessive, but not so high that there's no horsepower at freeway speeds.
Most cars and trucks have much lower differential ratios (between 2 and 3). With them, you need to keep the transmission or some kind of gear reducer. Your transfer case might work, but I suspect it has straight-cut gears that would be noisy, and it might not be designed for sustained use at high RPM.
I had a 5.17 in mine and it was really too high a gear for the GE motor they used, IMO.
That's correct. The CitiCars had undersized motors for the application. A direct-drive EV requires a bigger motor, so it can provide the high starting torque needed at low speeds without a transmission, but still have sufficient horsepower at high RPM for high speeds.
An interesting option might be to try space-saver spare tires.
These are crummy tires, only designed for emergency temporary use. If you want small cheap tires, try trailer tires instead.
-- "IC chip performance doubles every 18 months." -- Moore's law "The speed of software halves every 18 months." -- Gates' law -- Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org Read EVAngel's EV News at http://evdl.org/evln/ Please discuss EV drag racing at NEDRA (http://groups.yahoo.com/group/NEDRA)
