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Learning how to build Lotus Seven replicas...together!
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PostPosted: February 7, 2019, 2:50 am 
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Joined: April 19, 2018, 2:02 am
Posts: 57
This idea is for a BEC (Bike Engined Car).

I have a pretty decent hobby grade servo that can rotate about 360 degrees with the right PWM signals. It also says it has 38kg-cm torque.

The engine is a 2004 Honda CBR1000RR. Once you remove the shifter cover and shifter up-down linkage you have access directly to the shift drum. As near as I can measure each gear is 60 degrees apart with neutral halfway between 1st and 2nd.

It doesn't take much torque to shift it by hand (turn it 60 degrees to the next gear) while rocking the output shaft to get the dogs engaged. I would think that that servo would be able to turn it easily. I would also think you'd probably want a "buffer" or "servo saver" between the servo and the shift drum. Maybe just a rubber connector would work.

I think on the inside of the engine, the drum has a "star" cam with a follower that forces each gear location, so I wouldn't want that fighting against the servo, but I think each PWM point could be fine tuned to be pretty close to each notch.

I would probably want to isolate the servo from the motor case to prevent heat transfer maybe?

Then you could have shift paddles on the steering wheel. The concept works on the old Parallax Basic Stamp I have to control the servo. I would probably "upgrade" to an Arduino board or Raspberry PI or something like that. With a rubber coupler you could probably preload the shift drum too for a bit before shifting. Not sure how I'd cut the engine though. Maybe hook up a relay as a "kill switch".

Ever hear of such a thing? I don't know how reliable it would be. There would still probably need to be mechanical linkage as a backup.


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PostPosted: February 7, 2019, 11:13 am 
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Joined: April 1, 2010, 10:26 am
Posts: 374
It's been done before have you checked out sites like

https://www.flatshifter.com/flatshifter ... ckshifter/

Graham


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PostPosted: February 7, 2019, 4:40 pm 
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Joined: April 19, 2018, 2:02 am
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I can't tell what it is, is it an air shifter? Plus it costs more than my engine! I like the throttle blipper.


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PostPosted: February 7, 2019, 5:31 pm 
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Joined: April 1, 2010, 10:26 am
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I am not saying you have to buy there equipment but mine the site and forums for information. Pingle offers a ranger of shift kits.

https://www.pingelonline.com/content/demo-videos.asp


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