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  #11  
Old 05-26-2008, 11:10 PM
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Default Re: explain clutchless shifting

Quote:
Originally Posted by JRP3 View Post
I've heard that clutchless shifting can be hard on the syncros, more so on some transmissions than others. Also, you do lose the emergency physical disconnect between motor and trans when you remove the clutch. Something to consider.
With a kill switch installed, which should be there anyhow, there's no need for a physical disconnect.
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  #12  
Old 05-27-2008, 03:21 AM
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Default Re: explain clutchless shifting

You've still got the gear leaver in your hand. Push it into neutral if you need to disconect

As far as syncro's go I think the jury is out on whether they suffer in a clutchless setup, they are designed to slip every time the gears are changed in a regular setup. Yes they slip more in an EV but you rarely need to change gear anyway so I believe it's not an issue for normal use.
If your after MAX performance and want to have the motor buzzing in it's sweet spot all the time then yes, you would probably want to keep the clutch. There is however a chance of the inexperienced over revving the silent motor with the clutch in and you also have a lot more rotational inertia which saps acceleration.

Messes with your head dunnit?
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Old 05-27-2008, 07:19 AM
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Default Re: explain clutchless shifting

Quote:
With a kill switch installed, which should be there anyhow, there's no need for a physical disconnect.
True, though I prefer redundancy.
Quote:
Originally Posted by DVR View Post
You've still got the gear leaver in your hand. Push it into neutral if you need to disconect
Would there be a problem getting into neutral under load? I've never tried to shift into neutral under full throttle DC controllers fail full on after all.
Quote:
As far as syncro's go I think the jury is out on whether they suffer in a clutchless setup, they are designed to slip every time the gears are changed in a regular setup. Yes they slip more in an EV but you rarely need to change gear anyway so I believe it's not an issue for normal use.
Good point.
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  #14  
Old 05-27-2008, 07:25 AM
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Default Re: explain clutchless shifting

Just remember: Your clutch/gears would always have to be a last resort because your motor without load would just rip apart in the engine bay with full power but no load... Not something you would want to rely on.
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Old 05-27-2008, 06:16 PM
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Default Re: explain clutchless shifting

Just wanted to throw in my 2 cents.

My 97 S-10 is clutchless with an ADC motor, 2-1/2" dia. steel coupler, and New Venture 5 speed manual trans. I've been very pleasantly surprised at how smoothly this thing shifts. I generally drive in 2nd gear in town and 3rd gear on the highway (rural NW IL)

2nd gear: 2.37 gear ratio, 3.73 rear axle ratio, 8.84 final drive ratio, 3,000rpm = 26mph, 4,000rpm = 35mph
3rd gear: 1.49 gear ratio, 3.73 rear axle ratio, 5.56 final drive ratio, 3,000rpm = 42mph, 4,000rpm = 56mph

If I shift in the same manner and speed as I did with the ICE, I can feel a very slight drag on the synchros and the shift is smooth. If I take just a 1/2 to 1 second longeer to wait for the motor to slow slightly, the trans falls into gear completely smooth without any drag on the synchros whatsoever.

As far as safety, I can somewhat agree that not having a clutch could be an issue in a runaway, but you're correct that freewheeling a runaway is going to absolutely destruct the motor and probably the coupler and trans input shaft also. My system has three methods of disconnect. The secondary contactor disengages at throttle-off, the primary contactor disengages at key-off, and I mounted an emergency e-stop mushroom style palmswitch/panic button on the dash that kills both the primary and secondary contactor coils if activated. I don't know if I could physically force the transmission into neutral under full power; I really don't want to ever have to try.
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Old 05-27-2008, 06:28 PM
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Default Re: explain clutchless shifting

Quote:
Originally Posted by Carroll_1 View Post
My 97 S-10 is clutchless with an ADC motor, 2-1/2" dia. steel coupler, and New Venture 5 speed manual trans. I've been very pleasantly surprised at how smoothly this thing shifts. I generally drive in 2nd gear in town and 3rd gear on the highway (rural NW IL)

2nd gear: 2.37 gear ratio, 3.73 rear axle ratio, 8.84 final drive ratio, 3,000rpm = 26mph, 4,000rpm = 35mph
3rd gear: 1.49 gear ratio, 3.73 rear axle ratio, 5.56 final drive ratio, 3,000rpm = 42mph, 4,000rpm = 56mph

If I shift in the same manner and speed as I did with the ICE, I can feel a very slight drag on the synchros and the shift is smooth. If I take just a 1/2 to 1 second longeer to wait for the motor to slow slightly, the trans falls into gear completely smooth without any drag on the synchros whatsoever.

As far as safety, I can somewhat agree that not having a clutch could be an issue in a runaway, but you're correct that freewheeling a runaway is going to absolutely destruct the motor and probably the coupler and trans input shaft also. My system has three methods of disconnect. The secondary contactor disengages at throttle-off, the primary contactor disengages at key-off, and I mounted an emergency e-stop mushroom style palmswitch/panic button on the dash that kills both the primary and secondary contactor coils if activated. I don't know if I could physically force the transmission into neutral under full power; I really don't want to ever have to try.
Great post, Carroll
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