| Author | Message | ||
     Alexb |
Hi, My name is Alex and I am an engineering student at Swarthmore College building an Electric M2 as part of an extended class project. I could use some help with some of the frame geometry so if you have some time and a tape measure consider helping me out. For all measurements it would be best if the bike was unloaded so if there is anyway to lift the back of the bike so the shock is not compressed, do that first. 1st measurement, in the back top of the swing arm, in front of the rear wheel. the distance indicated in the first picture. (This may be a very awkward measurement, I am looking to determine the position of the swing arm transmission/engine mount relative to the rest of the swingarm. If you can think of a better measurement, feel free. )  2nd measurement, the distance from the eye of the shock where it connects to the swing arm to the ground.  3rd, fourth, fifth measurement. Distance from front of shock mount to ground, distance of shock (may depend on adjustment, whatever is on your bike), and distance from rear shock mount to ground.  Once again, thank you very much for anything you can measure or suggest. -Alex | ||
| Alexb |
Lastly, I will need to change the gearing as an electric motor will spin to much greater rpm. I would like something in the range of 5. Although that might be near impossible without some major reconstruction. I see that the M2 has a 65tooth rear pulley as stock. But the firebolt has a 72 tooth pulley. The screw pattern is different but if the alignment is the same then the different screw pattern can be accommodated. Does anyone have a picture from the back to the front of the firebolt rear pulley on a bike and also the same photo of the M2.-Alex | ||
| Blake |
What is the difference between D2 and D3, both are distance from rear shock mount to ground, yes? You have an electric motor to propel the motorcycle that exceeds 6,800 rpm? I'd be surprised if you do. | ||
| Bad_karma |
Alex Sounds like a challenge. What motor voltage are you going to use? Are you going to direct drive with a belt? What type of batteries are you going to use? What motor and controller? What speed and range are your targets? Good luck send pictures. Joe | ||
| Alexb |
D2 and D3, are both distances to the ground but I wasn't sure if the shock was inclined or perfectly horizontal, so a difference in those distances would be important. AC motors, of course depending on the number of poles, can exceed 12,000 rpm (trade off being some torque) An AC induction motor, most likely 48 volts. If we can not source an adequate hub motor (No way), then direct drive with a belt. | ||
| Djkaplan |
You'd be better off using a more conventional frame for your project. Without the engine (which is used as a stressed member on tube framed Buells) the efforts and resources you'll be spending working around the rear suspension issues and motor (please note I did not say 'engine') attachment points in the Uni-Planar frame would be better spent on other aspects of an electric powered motorcycle. Don't let enthusiasm cloud your judgement... time and money are probably already short and more important issues will need to be resolved for a successful project. | ||
| Alexb |
Response to Djkaplan, it turns out due to the power supply the buell frame will work better and in the end be much lighter than any other option. The removal of the engine as a stressed frame member will be replaced by the power system supports. The only reason I need the measurement is to try to make the end result have the same handling and ride quality. -Alex | ||
| Djkaplan |
If that particular frame is going to be a constraint for the project, the first thing I'd do is find a way to eliminate the rubber isolators completely and mount the swingarm block solidly to the frame. The isolators are there strictly to dampen vibration from an unbalanced engine, a non-existent issue for your project. Mounting the block solidly to the frame will keep you from having to precisely locate (and fabricate) the attachment points for the three (or four if you choose to use the extra location at the front mount) tie-bars that keep the swingarm and rear wheel aligned with the front forks and wheel. You'll still need to fabricate a very strong attachment point for the rear damper on the power source for the tube frame rear suspension. Good luck and keep us posted. | ||
| Alexb |
Hopefully someone will be able to take those measurements over the weekend, it would be a huge help. If you are unable to unload the back of the bike. You can make the measurements without doing anything and I can use the known length of the shock. Thanks | ||
| Rotzaruck |
Alex My M2 is hanging up in my Mom's basement with parts to fix it piled all around it. My standard shock is off and laying beside a M2Low shock(they are different lengths, bunch of threads here about M2/M2L differences, be aware). I'm trying to take time to work on it, but not doing too good. You may be working for the Buell Electrics Division by the time I measured anything. Riding season is a bad time to get guys to park long enough to measure something. It's pouring and lightening something fierce here, or you know what I would be doing! I was wondering though, if you might find someone close to you that might let you bring your tape and visit their bike. You might even luck up on a function and meet them there. Just a thought, but your profile says PA; in the Storm fronts are local groups, you might ask them there http://www.badweatherbikers.com/buell/messages/37/ 193523.html?1211856062and see what happens. (there may be more than one bunch up that way, I didn't look too hard) Rotzaruck | ||
| Alexb |
Thanks, I will give that a try as I have no other options. And anything you find time to measure would be great. -Alex | ||
| Djkaplan |
There is a better point to measure to than the rear shock mount. Plus, there is the matter of exactly which frame you may have; standard or Low. The hard point you have D2 linked to isn't 'hard', it's value in relation to the frame is a variable as the rear suspension goes through it's range of motion. A static point on the frame will give you an eaiser target and one not so sensitive to measurement tolerances; a point like the footpeg mounting hole on both sides of the frame. That would be an easier point to set the ride height to stock specs than the rear shock mount. The shock length (D4) is only important if you have a 'Low' frame. An M2L (Low) has shorter travel forks to match up to, so you'll need the slighter longer (but shorter travel) M2L shock. Do you know what type frame you have? If you have a standard frame, you can use any of the two standard shock lengths (14.7" or 16.5") because you'll be determining where the front shock mount is located on your power source. Just make sure the shock is horizontal and that should be that for the suspension geometry. I don't know the exact length of an M2L shock, but it has to be in-between 14.7" and 16.5". Compare the weight of the frame, with all the accoutrements it'll need for operation but the power source, to the wet weight of a stock M2 (about 475 lbs give or take) and that'll tell you how much extra weight you'll need to account for with spring rates when you find out how heavy the power source is. I can give you my footpeg hole height at full rear suspension extension, but it'll be higher than stock because I raised the rear ride height with an adjustable length shock (not a luxury you have with the stock Showa cannister shock). It's not such a big problem if you have a stock frame, but it could be if you have a Low frame. Also be aware than something as simple as a worn vs. new tire can change the measurement by a noticeable amount, so take the entire range of data into account. C'mon... get measuring guys! (Message edited by djkaplan on June 05, 2008) | ||
| Djkaplan |
This may help with identifying the frame... maybe not. http://www.badweatherbikers.com/buell/messages/476 23/327673.html | ||
| Alexb |
I have a standard M2 frame. Thanks for your info. Your right that this whole exercise of measuring is somewhat arbitrary as the measurements will change between bikes. To counter this I will try to build as much adjustment as possible. I am just trying to get a good idea of the ride height and the general inclination of the transmission/motor mount to the swingarm so that I dont build something which will have that mount hitting the swingarm during its motion. I hope i am being somewhat clear. DJkaplan if you could give me the footpeg hole height that might help even if you have raise the height. | ||
| Djkaplan |
Will do. | ||
| Djkaplan |
It's 11.875 inches to the very bottom of the frame footpeg extentions (not the center of the oblong hole for the footpeg) on my bike. The rear tire is almost down to the cords and the front fork has been raised 5/16" in the clamps, so that figure may be closer to stock than I realized. I couldn't get the D1 measurement, but you could eyeball the location close enough by setting the angle of the mounting pad and moving the swingarm through it's range of motion allowed by the damper travel. The angle of the mounting pad isn't exacly straight up and down, it's leaned to the rear by a few degrees. You can see the angle pretty good on bare chopper frames fabricated for XL engines. I think the angle could be off by a few degrees and still work fine for swingarm clearance. |
