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-   -   CVT Disadvantages (https://ecomodder.com/forum/showthread.php/cvt-disadvantages-6293.html)

DifferentPointofView 12-04-2008 11:27 PM

CVT Disadvantages
 
lol, the disadvantages that wikipedia has listed are quite humorous as they pretty much are advantages in reality. That and it describes the Typical American thought process when it comes to the way things should work.

Advantages

  • CVTs operate smoothly since there are no gear changes which cause sudden jerks.
  • Very few problems have been reported with the CVT transmission, lowering the cost of ownership.[citation needed]
  • The fluids do not have to be changed as often as in an automatic transmission.[citation needed]




    Heres the oddity that makes it seem like they couldn't find a good
    enough reason to down the CVT, so they scrapped together this
    Info. This explains why the regular american driver looks down at
    his foot and goes "What the F***!!!" when they use the CVT
    for the first time.

Disadvantages

  • CVTs operate smoothly and efficiently, without spending energy to jerk the car during a shift. This can give a perception of low power, because many drivers expect a jerk when they begin to move the vehicle. However, the expected jerk of a non-CVT can be emulated by CVT control software, thus eliminating this marketing problem.[citation needed]
  • Since the CVT keeps the engine turning at constant RPM over a wide range of vehicle speeds, pressing on the accelerator pedal will make the car move faster but doesn't change the sound coming from the engine as much as a conventional automatic transmission gear-shift. This confuses some drivers and, again, leads to an impression of a lack of power. This can be considered a disadvantage if the driver desires to hear the engine change tone.
  • CVT torque-handling capability is limited by the strength of their transmission medium (usually a belt or chain), and by their ability to withstand friction wear between torque source and transmission medium (in friction-driven CVTs). CVTs in production prior to 2005 are predominantly belt- or chain-driven and therefore typically limited to low-powered cars and other light-duty applications. Units using advanced lubricants, however, have been proven to support any amount of torque in production vehicles, including that used for buses, heavy trucks, and earth-moving equipment.

SVOboy 12-04-2008 11:30 PM

I didn't know the jerk during a shift was because the car was using so much power! Thank goodness I learned this *rollseyes*

DifferentPointofView 12-04-2008 11:37 PM

lol, when I accelerate in a normal Auto car, you don't feel the shifts cause of how little I'm using the gas. That and I keep my Jeep running good :thumbup:

I didn't know that having a smooth running car was an advantage! wait.. its also a disadvantage??? WTF!? *brain explodes*

trebuchet03 12-05-2008 02:54 AM

Quote:

Originally Posted by DifferentPointofView (Post 76681)

I didn't know that having a smooth running car was an advantage! wait.. its also a disadvantage??? WTF!? *brain explodes*

The cursed double edged sword....



Seriously, what's wrong with a double edge sword? I'd have more of a problem with the hilt-less sword :p

MazdaMatt 12-05-2008 08:43 AM

So... CVTs are used in heavy equipment!?!?!? I thought they were not in high production because they couldn't handle torque?! Why aren't all the EV people jumping all over this tech? Why aren't all the elctric motor companies offering computer controlled CVTs matched to their motors????? I love driving standard, but hell, a CVT would be sweet...

I would love to see a car with a "manual cvt" ... instead of a gear shift, a smooth lever :)

dichotomous 12-05-2008 09:08 AM

Quote:

Originally Posted by MazdaMatt (Post 76743)
So... CVTs are used in heavy equipment!?!?!? I thought they were not in high production because they couldn't handle torque?! Why aren't all the EV people jumping all over this tech? Why aren't all the elctric motor companies offering computer controlled CVTs matched to their motors????? I love driving standard, but hell, a CVT would be sweet...

I would love to see a car with a "manual cvt" ... instead of a gear shift, a smooth lever :)

audi offers this as a "6speed" program on their CVT TT. to ives the driver the thrill of shifting gears, even though its fastest just leaving it to do its job

MazdaMatt 12-05-2008 09:13 AM

Bleh, that's gross... i want a smooth lever that allows me to control the CVT ratio infinitely. Why on earth would anybody who knows anything about driving a sports car WANT to force the tranny to a ratio where the revs drop out of the prime zone?

bikin' Ed 12-05-2008 09:16 AM

I hate 'em
 
My wife has an altima V-6 with CVT. Just getting off of the gas pedal is akin to applying the brake. It has no coast in gear kind of affect. I also believe that if I were shifting a manual, I'd almost always be in a higher gear than it chooses for me. Both of these cost me at the pump.:(

MazdaMatt 12-05-2008 09:19 AM

That is entirely caused by bad software. Do you know if the gas pedal is cabled to the throttle plate? I would think that a truely perfect CVT system would use a computer controlled ratio AND throttle plate, making the pedal only a "speed setting" pedal... keep your foot where it is and the control system should align its throttle position and RPM on the best BSFC location for cruising.

dichotomous 12-05-2008 10:54 AM

the biggest problem CVT\'s have with people operating them is actually the "motorboating" effect. you press the pedal and the engine speeds up but you dont, untill it gets the ratio\'s and friction setup right. there are many out there now that dont do this. my sister loved hers in her saturn ion


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