dmopedMA
Active Member
- Local time
- 10:21 AM
- Joined
- Apr 14, 2017
- Messages
- 176
UPDATE (May 5):
I decided to update this first post pointing to the, I believe, milestones of this project:
First schema:
Custom made long shaft:
When I realized that only one shaft won't be enough to hold the second clutch:
First gearbox prototype:
First test of the gearbox, didn't engage the second gear:
Second prototype of the gearbox enclosure (thicket aluminium):
First test of the second prototype with weaker springs on the clutch:
ORIGINAL POST:
I'm working on a non-pedal chopper (https://motoredbikes.com/threads/4-stroke-schwinn-stingray-chopper-occ.51001/), the motor is a 49cc HS 4-stroke with the 4G transmission, using a 40t on the back wheel it gets 30mph.
I'm thinking on how to make it quicker and at the same time legal in MA, so if I use gears they have to be automatic (MA moped law)... I would love to have 2 gears, one for quick start from stop (right now it's not as quick as I would like) and other to get to 30mph (max speed by law). A classic jackshaft with bike gears won't be legal in MA and my bike does not have bike gears now.
I got an idea from go-karts using a second centrifugal clutch on a jackshaft, here a link with something similar: http://www.rcdon.com/html/grv-1_turbotug_project_12_01_0.html. From the 4G transmission I'll put two identical puller sprockets (10t) going to the jackshaft, on the jackshaft two sprockets, one big for the first gear and other small for the second gear (specific sizes to be determined), both connected with a chain to the correspondent 4g sprocket. The first gear will have a free-wheel, so it makes the jackshaft spin but not the other way around. The second gear will have a centrifugal clutch, so it will freely spin in low jackshaft RPMs and will engage the second gear when the jackshaft get close to the high rpms of the first gear. To make it clear, in low RPMs, the second gear will spin free (and faster) over the jackshaft that will be driven by the first gear and when the second speed engages, the freewheel of the first one will allow it to spin slower than the jackshaft. The output of the jackshaft will be connected to the back wheel on the right side.
Does anyone tried something like that before??? is this kind of system for sale?
EDIT: I just found a schema of the idea:
I decided to update this first post pointing to the, I believe, milestones of this project:
First schema:
automatic 2 gear jackshaft
Thank you for all the tips here. I want to start after my first reduction because I don't want to build a full transmission box with two shafts, I love my 4G transmission and I would like to keep it and just adding 1 more shaft (the jackshaft), will add less power loss (bearing, chains, etc)...
motoredbikes.com
Custom made long shaft:
automatic 2 gear jackshaft
Not gonna work either. The 2nd gear clutch has to be on the driven axle when side by side with a first gear chain. It needs to shift based on wheel speed, not engine speed. I see your point, didn't think about it. As it is now, second gear will disengage every time I release the throttle...
motoredbikes.com
When I realized that only one shaft won't be enough to hold the second clutch:
automatic 2 gear jackshaft
so, coming back to the 2 shaft (jackshaft) configuration, I order the rest of the pieces and should arrive this week. I'll keep updating Yeah that's why I log in here. Keep going working to achieve your engineering dream and you'll get there! :D
motoredbikes.com
First gearbox prototype:
automatic 2 gear jackshaft
I finally had some free time this weekend... I have the first version of the holder for the second shaft, I attach some pictures: Next step is to make holes for the bearing and install it on the bike. I'll probably cut the U-bolt, these are too long.
motoredbikes.com
automatic 2 gear jackshaft
I finally had some free time this weekend... I have the first version of the holder for the second shaft, I attach some pictures: Next step is to make holes for the bearing and install it on the bike. I'll probably cut the U-bolt, these are too long.
motoredbikes.com
First test of the gearbox, didn't engage the second gear:
automatic 2 gear jackshaft
If that happens, the gear will desengage... Let's see when I try it
motoredbikes.com
automatic 2 gear jackshaft
If that happens, the gear will desengage... Let's see when I try it
motoredbikes.com
Second prototype of the gearbox enclosure (thicket aluminium):
automatic 2 gear jackshaft
As long as you don't drive 65 in a 30 the police won't even think to ask about shifting.
motoredbikes.com
automatic 2 gear jackshaft
I'm thinking something like that too, but machining 4" block for more meat to support the bearings, and it anchors to the seatpost I can't machine anything, all this has being done with hand power tools... I'll attach to the frame with ubolts
motoredbikes.com
First test of the second prototype with weaker springs on the clutch:
automatic 2 gear jackshaft
someone else did an auto 2-spd jackshaft too. there was a freewheel with it I think but it was working
motoredbikes.com
automatic 2 gear jackshaft
What are the gear ratios of first and second gear, and what rpm does the second clutch begin to engage. With you engine now ungoverned you might be able to go with a higher engagement speed. I myself would try to get engagement speed at somewhere around 4700-5000 rpm, right around max torque.
motoredbikes.com
ORIGINAL POST:
I'm working on a non-pedal chopper (https://motoredbikes.com/threads/4-stroke-schwinn-stingray-chopper-occ.51001/), the motor is a 49cc HS 4-stroke with the 4G transmission, using a 40t on the back wheel it gets 30mph.
I'm thinking on how to make it quicker and at the same time legal in MA, so if I use gears they have to be automatic (MA moped law)... I would love to have 2 gears, one for quick start from stop (right now it's not as quick as I would like) and other to get to 30mph (max speed by law). A classic jackshaft with bike gears won't be legal in MA and my bike does not have bike gears now.
I got an idea from go-karts using a second centrifugal clutch on a jackshaft, here a link with something similar: http://www.rcdon.com/html/grv-1_turbotug_project_12_01_0.html. From the 4G transmission I'll put two identical puller sprockets (10t) going to the jackshaft, on the jackshaft two sprockets, one big for the first gear and other small for the second gear (specific sizes to be determined), both connected with a chain to the correspondent 4g sprocket. The first gear will have a free-wheel, so it makes the jackshaft spin but not the other way around. The second gear will have a centrifugal clutch, so it will freely spin in low jackshaft RPMs and will engage the second gear when the jackshaft get close to the high rpms of the first gear. To make it clear, in low RPMs, the second gear will spin free (and faster) over the jackshaft that will be driven by the first gear and when the second speed engages, the freewheel of the first one will allow it to spin slower than the jackshaft. The output of the jackshaft will be connected to the back wheel on the right side.
Does anyone tried something like that before??? is this kind of system for sale?
EDIT: I just found a schema of the idea:
Last edited: