Eric Patchem wrote: -------------------- I had recently inquired about directly coupling the motor to the axles using a fixed gear ratio. I had asked this because my car has an automatic transmission. I had read that an automatic transmission is less efficient than a manual. Which would be less efficient, the automatic tranny or the fixed gearbox (or chain)? I have a 93 ford festiva which I want to convert. A manual tranny probably wouldn't cost that much, but I am trying to do this conversion with as little stress as possible. I have many ideas, but I would like to bounce those ideas off anyone who will listen. --------------------
As a start here are a couple of answers from the FAQs at evparts.com: ============ Can I build an EV with an automatic transmission? An automatic transmission can be used in an EV conversion, but the modifications required to it are likely beyond the scope of most enthusiasts. The torque curve of an EV motor/controller combination is not the same as the ICE it replaces, therefore the shifting points (what speed/RPM the transmission shifts gears) will have to be changed. In older transmissions this can be accomplished by modifying the valve body within the transmission (the assembly that routes the fluid under pressure, activating the bands), or in the case of more modern transmissions, modifying the computer code that controls the electronic servos inside the transmission. Since the benefits are rather minor, the work required complex, and there is a decrease in overall efficiency compared to a standard transmission, you don't see very many automatic transmission EV's. Stick to donor chassis that came with a manual transmission from the factory and it will save you a lot of time, trouble and money in the long run. Mark Brueggemann 16JAN01 [EMAIL PROTECTED] Good arguments for the convenience of automatics have also been posted on the EV discussion list. An alternative to modifying valves and logic module code is just to shift into "L2" or "L1" instead of "D". With an electric motor, you may not even need to shift into "D" for the high gear. I would tend to keep the torque converter, install an external fluid pump, and do this. It would let me have more flexibility in choosing a donor vehicle. Then again, manuals seem to be a whole lot easier to work with. As in many other aspects of converting a vehicle, it comes down to what you want out of the vehicle. For many, the convenience is worth the slight decrease in efficiency. For others, premium efficiency and control is a requirement, and this requires a manual. David Brandt 5/21/01 [EMAIL PROTECTED] ==================== There are a couple (or more) other ways it can be done.... 1 - Provide pressure with an "always on" dedicated pump motor, no torque converter, always in gear, manual valve body. 2 - This is the setup in the Maniac Mazda: (GM powerglide), no motor to run pump, no torque converter, manual valve body. Pump and input shaft coupled directly to propulsion motors, (2 ADC 9" coupled end to end). Spin the drive motors, pressure builds,(quickly), clutches engage, car is propelled forward. (this feature contributes to the _maniac_ part, it makes for great launches) This setup may not be optimum for long clutch and band life :^D. Though there are probably more aftermarket drag racing upgrades for the powerglide than most any other automatic, it has been a workhorse in drag racing for many years. EV FAQ at evparts.com: http://www.evparts.com/faq/index.php More info on the Maniac Mazda: http://www.evparts.com/about/index.php?show=mazda.ihtml See GIF of Maniac Mazda make front suspension breakin' wheelie on this page: http://www.dcpowersystems.com Also, I believe that one or more of our controller gurus have also used the auto trans setup as a test bed/science experiment. Damon? Otmar? Roy LeMeur Seattle WA Hm: [EMAIL PROTECTED] Wrk: [EMAIL PROTECTED] EV Parts Inc. http://store.evparts.com 425 672 7977 EV Parts, your Electric Vehicle Parts Superstore My Electric Vehicle Pages: http://www.angelfire.com/ca4/renewables/evpage.html Informational Electric Vehicle Links: http://www.angelfire.com/ca4/renewables/evlinks.html _________________________________________________________________ Chat with friends online, try MSN Messenger: http://messenger.msn.com
