[jas32]

I'm hoping someone in the forum is a CVT expert and could enlighten me/us on the CVT in the current gen VSedan and VNote. I tried Googling this but came back more confused.

I understand the Note comes with the Xtronic CVT, this is a newer generation CVT with the wider drive ratio than previous CVTs.

1. Does the Xtronic CVT used on the Current VSedan/VNote includes the Sub Planetary Gear Set?

2. From my understanding, the Sub Planetary Gear Set has a low and high range. How does this work. i.e. when is it in low and when does it shift to high, and vice versa?

3. Nissan CVTs all use locking torque converters, how does this work, i.e. when does it go to lock up and when does it release?

Just intrigued by this technical innovation and would like to have a better understanding of how it all works.

 

[Vern in IL]

'14 Versa Note
The locking Torque converter on mine basically unlocks at low speeds, it is very annoying.

For example, if I was to slow down <10mph the 'verter will unlock, but when you press the gas pedal, you can definitely feel it locking up!:surprise

 

[jas32]

'14 Versa Note
The locking Torque converter on mine basically unlocks at low speeds, it is very annoying.

For example, if I was to slow down <10mph the 'verter will unlock, but when you press the gas pedal, you can definitely feel it locking up!:surprise

The torque converter HAS TO unlock at some point before the vehicle stops (I agree around 10 MPH), otherwise the engine will stall (just like not pushing the clutch in, on a manual trans vehicle). Conversely it is designed to lock up fairly quickly to save on fuel when accelerating.

I would think the lock up speed when accelerating will be dependent on how much you open the throttle. I'm curious on how this interacts with the CVT itself and the Sub Planetary Gear Set.

 

[Note-ified]

CVT with an auxiliary gearbox for mini and small FWD vehicles | JATCO Ltd

this should shed some light on things

 

[jas32]

CVT with an auxiliary gearbox for mini and small FWD vehicles | JATCO Ltd

this should shed some light on things

Thanks Note, I guess that web page did not pop up on my Google search. I guess I should have searched Google Japan.

This is the first time I saw anything documented on the 2 speed gearbox in graphical form (i.e. the video shows the low and high operating range of the aux gearbox).

I am now wondering if the observed "fake shift" that happens between approx 10-30 MPH (where the engine RPM momentarily dips for about 1/2 sec) is in fact the aux gearbox shifting from low to high? .... Kinda makes sense.

 

[SilverV]

That's why the car is best driven slowly when you take off from a stop, let the TC lockup and switch to high gear ratio then you can really get into the gas.

Sent from AutoGuide.com Free App

 

[jas32]

That's why the car is best driven slowly when you take off from a stop, let the TC lockup and switch to high gear ratio then you can really get into the gas.

Sent from AutoGuide.com Free App

You are absolutely right. If you are aggressive on the throttle from a stop the engine tends to hang on to the lower gear ratio, making the engine scream.

I think the torque converter locks up fairly quickly regardless. Much like a clutch, it appears it is only used to help launch the car and prevent stalling the engine when coming to a stop. With the flexibility of the CVT I don't see any reason to use any slip once the car is moving.

 

[SilverV]

What's interesting is Nissan will be introducing on several popular models including the Versa a new D-Step Shift logic that will mimic a geared automatic for CVT's.

Personally I don't want a CVT to behave like a geared automatic, what's the point of it being "continuous" if it has simulated shift points?

According to the article below it will simulate shift points at 4k RPM. I hope it's a option which can be turned off but I can understand if it helps ease peoples minds that their transmission might be broke.

http://www.autonews.com/article/20140713/OEM03/307149936?template=mobile&X-IgnoreUserAgent=1

Sent from AutoGuide.com Free App

 

[Note-ified]

What's interesting is Nissan will be introducing on several popular models including the Versa a new D-Step Shift logic that will mimic a geared automatic for CVT's.

Personally I don't want a CVT to behave like a geared automatic, what's the point of it being "continuous" if it has simulated shift points?

According to the article below it will simulate shift points at 4k RPM. I hope it's a option which can be turned off but I can understand if it helps ease peoples minds that their transmission might be broke.

http://www.autonews.com/article/20140713/OEM03/307149936?template=mobile&X-IgnoreUserAgent=1

Sent from AutoGuide.com Free App

i had heard about them doing this, i'm just wondering if they will be doing updates to the previous model years also.

 

[jas32]

.....Personally I don't want a CVT to behave like a geared automatic, what's the point of it being "continuous" if it has simulated shift points? .....http://www.autonews.com/article/20140713/OEM03/307149936?template=mobile&X-IgnoreUserAgent=1

The point is I'm sure Nissan is still getting a lot of complaints from customers who are not used to or cannot get used to the fact that they have a more efficient powertrain and are actually saving fuel.

I think the main issue with CVT is our brains were all trained to hear the engine go through all the gears (from manuals to stepped auto trans) with direct correlation between engine speed and vehicle speed on each gear. This goes away with CVT and instead the car sounds like a motor boat.

If we can just completely eliminate engine noise, people would not notice a thing and we should be all set!

BTW, back in the mid 90's I drove one of the first production Honda CVTs, boy that was really bad. A few years later I drove an Audi CVT, this one was programmed to have simulated steps which very much mimicked a standard stepped transmission.

 

[jas32]

i had heard about them doing this, i'm just wondering if they will be doing updates to the previous model years also.

This will all depend on how widespread the complaints are in the field. Although this is "just software" and a simple ECU reflash by the dealer, it takes a bit of time and effort to get things like these go through EPA recertification before it can be released as a service/field fix.

This also assumes that there are no hardware differences between the current and previous model years.

 

[Vern in IL]

Oh yeah, TOWING VOIDS THE WARRANTY.

Probably to protect the CVT from blowing up? Yet in other countries they can tow, only in the United States is towing a no no.