hyve wrote:Jeremy, getting back to the question of clutch or not: this million or so vehicles with no clutch or gearbox; what would be a typical motor kw output to vehicle all up weight, to permit one-speed transmission?
You are actually asking 2 questions here, clutch or no clutch and multi speed gearbox or fixed speed. Regarding the question of gearboxes, on the Agni motors website FAQ section is a formula for figuring out if a fixed speed gearbox will be suitable for your requirements,
click here. Find the section half way down called “Is the motor suitable for my vehicle?" This is of course for their motors but should give you somewhere to start.
Back to the clutch or no clutch discussion, after doing the Volvo conversion with no clutch when I started on the Fiat conversion, the clutch went straight into the bucket. Reverse gear in the Volvo is lively, but I am used to it. I will put some sort of simple half speed throttle on it for reverse at some point, but it's not much of a problem. so it's a little way down on the list of things to do. If someone else was driving it or I needed to do a lot of parallel parking it would move up the list.
It was suggested that a missed gear could potentially cause a problem with over reving the motor. In my case it has not been a problem. Gear changes take around 2 seconds for the gearbox syncros to match speeds. I could see that you could miss a shift if you need a quicker gear and tried to rush it. If this is your situation then keep the clutch. I find that on my 11 mile commute I only need 1 or 2 gear changes which offsets the slow gear change.
Sometimes the gearbox doesn't engage 2nd or reverse properly, we all have experienced that at some time. In my case the motor's own ineretia, even without the weight of a clutch and flywheel, and the throttle ramp built into the Curtis controller prevented the motor from "flying apart".
The question of clutch or no clutch will ultimately depend on what you require or expect out of your vehicle. Mine are availible for a test drive to anyone who finds themselves in the Scottish Borders, just PM me.
Oh and for a high voltage high speed fixed ratio vehicle with no clutch, how about the tesla roadster. O.K. so not exactly millions made, but its a start.