Speed UTV

In the recent brief video I was struck by the decision to go to Nikasil at this stage of the process. I thought it was odd that they decided against it in the first place, but RG did cite his reasoning at that time. 

 
Well it is a new year and new hope the Speed UTV will be in production soon.  The road to 200 pages continues on.  LOL!

Happy New Year!

 
I'd be interested in the shift on the fly idea, and how it now sounds like you have to be capable of shifting a Roadranger to make it happen. Didn't sound that way at the outset.

 
1HasBeen said:
I'd be interested in the shift on the fly idea, and how it now sounds like you have to be capable of shifting a Roadranger to make it happen. Didn't sound that way at the outset.
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RG spoke a bit about it, and unsurprisingly the CVT seems to be part of the issue.  The trans is a dog-box, which generally is more suitable for clutch-less shifting but still needs torque to be reduced for a shift and requires better matching engine speed to the next gear (up or down) than a synchro (as in, synchronizer) trans.  My ASSumption is that the CVT causes load to still be put into the trans input shaft because of all the momentum of the secondary bolted to it.  There's also probably a longer lag from throttle-lift to load being reduced in the trans as the clutches have to do their thing... and they're not really designed to fully remove load.  So it's probably an issue where you lift throttle, but the clutches are still imparting load in the trans so you can't shift, by the time the clutches reduce load into the trans enough to allow the shift now the motor has slowed down way more than you'd want (I'm talking upshifts here) and it's not a clean shift.  Going for a downshift seems even more problematic, you lift and wait for the whole load reduction song 'n dance, then try to blip the throttle to let it slip into the next gear but the CVT is going to back-shift and hit the trans with load because of the throttle blip rather than just a light spin-up to help match the input shaft speed to the required rpm to be in the next lower gear at the given vehicle speed. 

-TJ

 
tjZ06 said:
RG spoke a bit about it, and unsurprisingly the CVT seems to be part of the issue.  The trans is a dog-box, which generally is more suitable for clutch-less shifting but still needs torque to be reduced for a shift and requires better matching engine speed to the next gear (up or down) than a synchro (as in, synchronizer) trans.  My ASSumption is that the CVT causes load to still be put into the trans input shaft because of all the momentum of the secondary bolted to it.  There's also probably a longer lag from throttle-lift to load being reduced in the trans as the clutches have to do their thing... and they're not really designed to fully remove load.  So it's probably an issue where you lift throttle, but the clutches are still imparting load in the trans so you can't shift, by the time the clutches reduce load into the trans enough to allow the shift now the motor has slowed down way more than you'd want (I'm talking upshifts here) and it's not a clean shift.  Going for a downshift seems even more problematic, you lift and wait for the whole load reduction song 'n dance, then try to blip the throttle to let it slip into the next gear but the CVT is going to back-shift and hit the trans with load because of the throttle blip rather than just a light spin-up to help match the input shaft speed to the required rpm to be in the next lower gear at the given vehicle speed. 

-TJ
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Also my ASS-umption. Just interesting to get an insight into whether they had not anticipated something that seems rather obvious, or if something else is at play.

 
tjZ06 said:
RG spoke a bit about it, and unsurprisingly the CVT seems to be part of the issue.  The trans is a dog-box, which generally is more suitable for clutch-less shifting but still needs torque to be reduced for a shift and requires better matching engine speed to the next gear (up or down) than a synchro (as in, synchronizer) trans.  My ASSumption is that the CVT causes load to still be put into the trans input shaft because of all the momentum of the secondary bolted to it.  There's also probably a longer lag from throttle-lift to load being reduced in the trans as the clutches have to do their thing... and they're not really designed to fully remove load.  So it's probably an issue where you lift throttle, but the clutches are still imparting load in the trans so you can't shift, by the time the clutches reduce load into the trans enough to allow the shift now the motor has slowed down way more than you'd want (I'm talking upshifts here) and it's not a clean shift.  Going for a downshift seems even more problematic, you lift and wait for the whole load reduction song 'n dance, then try to blip the throttle to let it slip into the next gear but the CVT is going to back-shift and hit the trans with load because of the throttle blip rather than just a light spin-up to help match the input shaft speed to the required rpm to be in the next lower gear at the given vehicle speed. 

-TJ
Click to expand...
FBW right?  Seems they could rev-match it to expected RPM like most MT cars do today with auto rev-matching.  Mapping would be a little more complex given CVT, but doable.

 
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