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There is no single "best" chassis for conversion. There are always trade-offs, and you have to decide your priorities. You want something as light and aerodynamic as possible that's still strong and roomy enough for 16 - 20 batteries, with accessibility for periodic battery maintenance. In general terms, this means most manual transmission 4-cylinders compact sedans and light trucks are possible. Some 6-cylinder ones will work, but not as well. 8-cylinders are almost always too heavy. Hatchbacks are good.
The most popular models are VW Rabbit, Porsche 914, Honda Civic, Honda CRX, Ford Escort, and aircooled VWs. In pickups, the popular choices are the Chevy S10, Ford Ranger, and Mazda pickups. Pickups do not have as much range as sedans.
If you are looking for the easiest car to convert, that would be the Rabbit or Porsche 914, because there are fully pre-fabbed custom kits available for these models. The trade-off here is cost, because you pay more for all that design and prefabbed parts. The benefit is a quick, easy installation with a proven design. This can be done in as little as 40-60 hours if you are relatively handy with tools.
Next easiest would be a pickup because of all the nice open battery space available. This would be a lower cost, more generic kit, but would require more of your time and effort to design and fab the custom pieces. The same general situation would apply to a car other than the Rabbit or 914, but the design would be a little tougher, due to a smaller, more complicated battery space. This is at least 200 hours' work.
You can optimize a car for speed or acceleration, usually at the expense of range. This means using lighter batteries that may smoke tires and hit high speeds, but may only give 20-30 miles range.
Many people want to optimize for range. The Voltsporsche has been our best performer in this respect. In good real life conditions (some in-town and some freeway, relatively flat, smooth traffic flow, warm weather, efficient driver) it can do 80-100 miles. (You wouldn't want to depend on that range on a daily basis, as you want some reserve for unexpected traffic snarls and detours, etc.)
However, the Voltsporsche is a 2-person car. For 4 people plus a load of groceries, something like the Voltsrabbit is a good choice. The basic version uses 96 volts, but there is an option for 108V (2 more batteries under the rear seat) for a little more speed and range.
If low cost of conversion is your priority, an aircooled VW might be the choice. It doesn't need power brakes or a rear motor mount, and 96V is about the most you can fit into it. The trade-off will be a very basic level of performance, and you'll probably have to sacrifice the back seat to batteries.
If you fill out our free Project Review Form, we can analyze your particular driving needs, and recommend what type of chassis and system might be best for you.
The conversion does retain and use the original transmission and clutch. The DC electric motor's rpm limits are very similar to those of the original gas engine. For this reason, the electric motor needs the transmission to achieve a full range of performance from standstill to freeway speed.
The clutch is needed for several reasons. For one thing, it makes the car much easier and more pleasant to drive. Although you can drive without a clutch, it requires developing a very fine skill to do so without starting with an abrupt jerk. The clutch also reduces wear on the transmission parts, and acts as a safety feature, so you can easily disengage the motor from the wheels if you develop a problem while under power.
Automatic transmissions are almost never used in conversions, for several reasons. We do not deal with them at all. Automatic transmissions have energy losses that reduce performance. Also, the shift points will not be appropriate on hills, and may damage the motor. Finally, the automatic relies on an idling engine to keep the hydraulic pressure up. When an electric car stops at a stoplight, the motor stops turning, and the transmission loses pressure. When the light turns green, there is a delayed response to the throttle while pressure builds up. This could be dangerous. The problem can be fixed by causing the electric motor to idle at stops, but this wastes energy. Or you could add a separate pump for the transmission, but this adds expense, complication, and a possible failure point.
Most of the vehicles best suited to conversion are economy models without a lot of power accessories. However, power windows, radios, CD players, etc., are no problem if you do have them. The EV still has a 12V accessory battery. This is charged by a DC/DC converter, which taps the main battery pack at a very low amperage to keep the accessory battery charged.
Most of these vehicles do not have or need power steering. It can be accommodated if you have to have it, but it will add several hundred dollars of expense to the project.
You DO want power brakes if you have the option. You will be adding a lot of weight to the car, and you need to be able to stop safely. This can be handled easily with a vacuum pump, reservoir, and switch.
In the early days of conversions, these were used as electric car motors because there wasn't much else available. However, they have several problems. They are designed to be used at a much lower voltage, so they have to be seriously overvolted in a car. Even then, performance is marginal. They are designed to run at higher rpm, so that in a car, they are consistently running in the least efficient part of the power band. They suck up lots of amps. This reduces range, and stresses other components. Due to both of these issues, they tend to burn up in use.
They are also not compatible with modern controllers unless you add an inductor. They have an odd splined shaft, which is very expensive to mate in the adaptor. They also require bearings in the adaptor.
There are much more appropriate motors available today, so there is no reason to use one of these in a car.
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