# Shifting Torque

8 replies to this topic
• # Suleman

Posted August 22, 2015 - 01:28 PM

Hey there! I have been working on a servo shifting for Yamaha WR450-F for which I have to evaluate the average shifting torque? And the critical factors on which its value depends?

• # Krannie McKranface

Posted August 22, 2015 - 01:48 PM

How would we know that, if there no reason to know that until you invent the device you are talking about.

I am assuming you are talking about linear movement torque to overcome the shift drum detent.

• # Suleman

Posted August 23, 2015 - 06:39 AM

How would we know that, if there no reason to know that until you invent the device you are talking about.

I am assuming you are talking about linear movement torque to overcome the shift drum detent.

I am working for Formula student car.Yeah I am talking about the linear movement torque or the amount of rotation in degrees needed for a single shift. I just wanna know that on what factors it depends? And if any of you guyz have idea about that, please share..

Thanks

• # grayracer513

Posted August 26, 2015 - 06:27 AM

Get an angler's scale, or any other that can weigh something hanging on a hook, and see how much force is required to accomplish a shift into gear with the engine idling.  Then correct for the shift lever length.  Figure you will need about 3-4 times that much torque for a good positive shift.

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• # bikedude987

Posted August 26, 2015 - 02:03 PM

I don't mean to be a jerk, but it seems like this is an extremely easy problem you have.  Force x Distance = Torque.  Go shift the motor in question at different angle speeds and measure the force needed at a specific distance.  Like Gray said, a solid factor of safety is good too.

Make sure the actuator applies the force over enough time to complete the shift as well, not just an impact, include a dwell time at the peak.

• # Suleman

Posted August 27, 2015 - 09:34 AM

Thanks for attention!

Well, I know how to evaluate the torque..The question is on what factors it depends?  When engine rpm is high , will there be any change in the required force? Does downshifting force is exactly equal to that for up shifting?

• # beezer

Posted August 27, 2015 - 11:59 AM

Most air shifters I've seen for drag bikes kill the ignition for a bit so it can shift.

Otherwise the trans is almost locked in gear.

• # stainless601

Posted August 27, 2015 - 05:07 PM

I think that you should look into Ducati's " Quick Shift" technology. I had the pleasure of riding the 1299cc street bike so equipped .
It allows full throttle shifts without touching the Throttle or Clutch! It works on down shifting as well. That v twin was a beast and the shifting was amazing! That said I don't see this happening on a dirt bike.

• # bikedude987

Posted August 28, 2015 - 06:48 AM

YES, engine rpm and load will effect shifting torque.  I would expect LOAD is your most prominent factor, once you get past idle (too slow and you risk not engaging the dogs).  Killing the engine momentarily (or clutching/blipping the throttle) will be necessary to shift well with this setup.  I assume the driver is still controlling the clutch/throttle, so some driver training can overcome this.