On Jan 4, 2008 10:20 AM, SteveS <[EMAIL PROTECTED]> wrote: > Thanks for the offer Andrew - looks like a good candidate. However I > just found out about a possible donor in my area; a BMW; which is what I > really hoped to get. Yeah, I know, I won't be able to change gearing > easily, but I want to give it a shot. Funny how I've been looking for a > chassis for a while and suddenly two come up. If the beemer doesn't pan > out, I'll check back on yours. And I just cleaned out the basement so I > have room for a new project! > > - SteveS
Hi Steve, Sorry I forget some of the details of your project, but I think you're planning on using a fairly low power motor? Your mention of using a BMW donor really got my attention, since I did a lot of thought about converting a /5, /6, /7 airhead. If that's the kind of BMW you're looking at, keep the transmission! It's one of those rare motorcycle transmissions that uses a dry clutch and is completely independent from the engine. Think about it - the reason almost all car conversions use the original transmission is because it's already there and allows a smaller motor. The reason most motorcycle conversions don't use the original transmission is because it's too much hassle to deal with a wet clutch and shared lubricant - which doesn't apply to you. Just make a simple adapter plate and clutchless coupler*. Now you have the multiple gear ratios that a small motor so desperately needs. If your conversion shows promise, it's an easy matter to swap out the motor for something more robust later on. You might even be able to make one adapter that accepts your current motor choice and your eventual upgrade. (And yes, I think you'll be wanting that upgrade.) Personally, I'd run a 36-48V motor with 96V of AGMs. The BMW airhead boxer has a very high GVWR for its weight, allows the use of a transmission and places the motor in an ideal position for cooling. Plus, it's an all-around nice bike. I think it's one of the best possible donors. Chris *There's a constant debate on the EV list (a list which I sadly had to admit I don't have time for any more) about running clutchless. With a car transmission, shifting without a clutch means abusing the synchros. Some cars do better than others. Motorcycles don't have synchros. But BMWs already shift kinda clunky, and not using a clutch will make it worse. OTOH, a clutch and flywheel add a lot of dead weight and (much worse) rotational weight. If it was me, I'd dimension my adapter to accommodate a clutch, but install a simple coupler and try running clutchless. If it wasn't to my liking I'd aggressively remove material from the original flywheel (to 1/2 or less its original weight - maybe even 1/3) and put the clutch back in.
