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Discussion Starter #1
I can't find the info anywhere.

Is the Gen 2 transaxle / transmission a CVT?

I know it has a chain, and 2 electric motors, and like 3 clutches, and the engine attached to planetary gears or whatever.

I just wanna know, is it a CVT or not??
 

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Discussion Starter #3

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no
chain drive is not through variable sheaves(pulleys)
There is more than one type of CVT. Per this article, there are modes where gen2 is an eCVT (ICE can operate in wide rpm range while vehicle speed is constant).
 

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There is more than one type of CVT. Per this article, there are modes where gen2 is an eCVT (ICE can operate in wide rpm range while vehicle speed is constant).
There is more than one type of CVT but they all have one thing in common, they have continuously variable gear ratios. The Volt transmission dos not. It has only two ratios. One where one electric motor is connected and one were two electric motors are connected. Whether the ICE motor assists in power doesn't change this. Therefore it doesn't meet the definition of a CVT or an eCVT .
 

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There is more than one type of CVT but they all have one thing in common, they have continuously variable gear ratios. The Volt transmission dos not. It has only two ratios. One where one electric motor is connected and one were two electric motors are connected. Whether the ICE motor assists in power doesn't change this. Therefore it doesn't meet the definition of a CVT or an eCVT .
A transmission that allows the ICE (that is providing torque to the wheels) to continuously vary it's speed while keeping the vehicle speed constant is, by definition, a CVT (in this case by being an eCVT).

From the article I linked above:

Extended range, when the gas engine starts up, now has 3 modes instead of 2 in the original Voltec design. The new operating modes increase efficiency, especially in city driving. In 2 of the modes the motors can be dynamically “mixed” with the gas engine output in an eCVT or electrically continuously variable transmission mode. The 2 Modes where “mixing” is used are Low Extended Range and High Extended Range.

Low extended range is technically an "input split" style of eCVT. In this mode the large motor MGB is driving the vehicle through PG 2 to the wheels with the PG 2 ring gear locked together with the mechanical power from the gasoline engine on PG 1 and the electrical power generated by MGA on PG 1. By adjusting the power generated by and used by the two motors the engineers can put the ICE at its most efficient operating point.


It gets variable "electronic" gear ratios by using the motors thru the planetary gearsets. Granted, it does not always operate in this mode, but when it does it absolutely is an eCVT.
 

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Discussion Starter #7
I am satisfied and happy to hear that it does not have the variable "cones/pulleys/sheaves" that the typical CVT has.....

as they seem to be a common failure point.
 

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had to think about that for a bit as well, becouse electrically it can be a CVT through the electric motors and engine
its just not a mechanical CVT like a snowmobile
 

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Discussion Starter #12
Also, it seems the trans has a regular-looking kinda chain drive.....with actual links and stuff.....whereas a CVT trans usually has a belt-looking metal band kinda thing going on.
So more clues not a "real" CVT by standard definition.
 

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Also, it seems the trans has a regular-looking kinda chain drive.....with actual links and stuff.....whereas a CVT trans usually has a belt-looking metal band kinda thing going on.
So more clues not a "real" CVT by standard definition.
The chain drive is just takes the place of the idler gear in the Gen I. There are two speeds, MGB connected and MGA and MGB connected (or engine assist for that matter). The fact that the "transmission" changes speed as the motors change speed doesn't make it a CVT anymore than my 5 speed transmission in my TR7 is a CVT.
 

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Discussion Starter #14
The chain drive is just takes the place of the idler gear in the Gen I. There are two speeds, MGB connected and MGA and MGB connected (or engine assist for that matter). The fact that the "transmission" changes speed as the motors change speed doesn't make it a CVT anymore than my 5 speed transmission in my TR7 is a CVT.
Haha! TR7 cvt. True that.

btw, the show "wheeler dealers" did an episode on the TR7, maybe you'd find it interesting.
 

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Haha! TR7 cvt. True that.

btw, the show "wheeler dealers" did an episode on the TR7, maybe you'd find it interesting.
I'm aware, haven't seen it yet.
 

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...The fact that the "transmission" changes speed as the motors change speed doesn't make it a CVT anymore than my 5 speed transmission in my TR7 is a CVT.
In your 5 speed, at a given gear and engine rpm, you will always be going the same vehicle speed, you can not continuously vary the rpm and keep the speed constant (you can shift gears and have discrete jumps, but the ratios are fixed). In either gen Volt, there are modes where you can continuously vary the engine rpm (while providing engine torque to the wheels) over a decent rpm range while holding vehicle speed constant. That is what makes it an eCVT, the motors/gears allow the ICE to vary speed and keep vehicle speed the same (i.e. not a fixed ratio between engine rpm and vehicle speed).That is the very definition of a eCVT (if you don't believe me, ask Toyota and their Hybrid Synergy Drive), which again is a special type of CVT.
 

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Complicated! Noticed it says the compression ratio is 12.5:1, and yet its recommended 87 octane still, wow!
The newer GM Ecotech engines can handle higher compression on lower octanes.
 

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In your 5 speed, at a given gear and engine rpm, you will always be going the same vehicle speed, you can not continuously vary the rpm and keep the speed constant (you can shift gears and have discrete jumps, but the ratios are fixed). In either gen Volt, there are modes where you can continuously vary the engine rpm (while providing engine torque to the wheels) over a decent rpm range while holding vehicle speed constant. That is what makes it an eCVT, the motors/gears allow the ICE to vary speed and keep vehicle speed the same (i.e. not a fixed ratio between engine rpm and vehicle speed).That is the very definition of a eCVT (if you don't believe me, ask Toyota and their Hybrid Synergy Drive), which again is a special type of CVT.
If you can vary the engine speed while it is connected to the drive train and keep constant car speed, you would need a large slipping clutch or a torque converter which it doesn't have. either the engine is direct connected or it's not. If it's connected, the engine speed has to match car speed. If the engine isn't connected while doing that, well I can do the same thing in neutral in my 5 speed. Don't know how the Toyota eCVT works but it's not going to be GM's. There is no CVT in a Volt.
 

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Discussion Starter #19
In your 5 speed, at a given gear and engine rpm, you will always be going the same vehicle speed, you can not continuously vary the rpm and keep the speed constant (you can shift gears and have discrete jumps, but the ratios are fixed). In either gen Volt, there are modes where you can continuously vary the engine rpm (while providing engine torque to the wheels) over a decent rpm range while holding vehicle speed constant. That is what makes it an eCVT, the motors/gears allow the ICE to vary speed and keep vehicle speed the same (i.e. not a fixed ratio between engine rpm and vehicle speed).That is the very definition of a eCVT (if you don't believe me, ask Toyota and their Hybrid Synergy Drive), which again is a

My original post mainly was just if it had a CVT-type belt and variable "sheaves" that belt rode on......
which the Volt does not.
and I see this is good.

Is the Volt an eCVT or not? I will just watch you guys figure that one out. :)
 

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Discussion Starter #20
In your 5 speed, at a given gear and engine rpm, you will always be going the same vehicle speed, you can not continuously vary the rpm and keep the speed constant (you can shift gears and have discrete jumps, but the ratios are fixed). In either gen Volt, there are modes where you can continuously vary the engine rpm (while providing engine torque to the wheels) over a decent rpm range while holding vehicle speed constant. That is what makes it an eCVT, the motors/gears allow the ICE to vary speed and keep vehicle speed the same (i.e. not a fixed ratio between engine rpm and vehicle speed).That is the very definition of a eCVT (if you don't believe me, ask Toyota and their Hybrid Synergy Drive), which again is a special type of CVT.
My original post mainly was just if it had a CVT-type belt and variable "sheaves" that belt rode on......
which the Volt does not.
and I see this is good.

Is the Volt an eCVT or not? I will just watch you guys figure that one out. :)
 
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