CVT Disadvantages

[MazdaMatt]

So in effect, ALL of the dissadvantages are in user PERCEPTION? And the advantage is that it makes the car more powerful and fuel efficient? Well we got used to replacing horses with engines, i think we can get used to the motorboat effect and coasting with your foot on the gas.

[DifferentPointofView]

My mom's caliber has CVT with "Autostick"

Basically, its a clutchless manual sort of thing. when your shifting manually, you can control what gear you want it to be in. The quietness is a factor when using the autostick option because you have to look at your Tachometer cause the car is so dang quiet.

But I love it. when you accelerate, it goes to just under 2000 RPM and stays there, and when you get to 55, it is still there. and its so smooth. *drools* I can't wait till I get it, I'll be 2 years into college, but It'll still be better than driving my Jeep around thats for sure. I can pull the max out MPG's on my jeep by driving like an idiot. I don't know how people complain about getting like 23 mpg in it. How do they do it??? I got 30.6 driving 75 from here to Kansas city and when I got there thats when we filled up.

Also, when your listening to music, the details from your music really sing.. mmmm

[MazdaMatt]

What is Autostick and how does it relate to CVT?

[DifferentPointofView]

Its a feature that the Caliber R/T's CVT2 transmission has that allows you to shift like its a manual, but on an automatic transmission. It creates simulated Gear ratios that allow you to control the ratio of the CVT's belt/pully's whatever type of CVT it is so that you can have more control in situations like snow, acceleration, and want an overall Manual transmission experience without the actual manual transmission. Makes it good if you like driving stick but your wife has no idea how to drive stick. You can also keep it in a high gear ratio around town to lower RPM's.

When using the Autostick feature in the Caliber, 1/4 mile times are faster and you don't have to wait for the computer to decide what position the V belts need to be at in order for the best gear ratio, you decide that, and launches are faster. Autostick is only available on the higher end models, mostly for performance applications. But you can also use it in town or while coasting downhill for better coasting and lower RPM's for better fuel economy. You gotta know how to drive it though.

[MazdaMatt]

I wish i had funding dollars because i could totally develope a control algorith that would be way more advanced that anything that you all are telling me that production cars do.

It is absolutely SILLY that this autostick mode would have a faster quarter mile than CVT mode. CVT mode should simply lock the engine RPM at max power and change the gear ratio to suit wheel speed. It should not be beatable in acceleration OR mpg.

[dichotomous]

Originally Posted by MazdaMatt

I wish i had funding dollars because i could totally develope a control algorith that would be way more advanced that anything that you all are telling me that production cars do.

It is absolutely SILLY that this autostick mode would have a faster quarter mile than CVT mode. CVT mode should simply lock the engine RPM at max power and change the gear ratio to suit wheel speed. It should not be beatable in acceleration OR mpg.

so you'd need a unit that could handle intense torque on a sliding ratio, not easy to put together, and you'd need to know exactly what the driver wanted, right then, all the time, and how the engine and transmission should be configured for best performance either way, and you'd need to factor in the differences in people driving, and make sure it all works best, and lighter than the manual, and reacts just as quickly, and costs about the same. otherwise it either wont work or people wont buy it. hence the case with the cailber.

[DifferentPointofView]

yea, the main reason is price. otherwise, it will either not sell or no one will buy it. they kept it simple and went with nissan's already developed technology.

[MazdaMatt]

All i'm proposing is a better control system for the CVT, no mechanical changes... except that i would want the gas pedal to be an elctronic input and have actuators at both the throttle plate and the cvt gear so both engine and tranny are in my control.

I think the only hurdle is that people are dumb... which really blocks most of the world's progres... it would just feel "different" and that my drive off the idiots. It would always cruise at the throttle/rpm that would produce the required HP to maintain speed while being at the most efficient available point on the BSFC chart, and at pedal positions above neutral it would seek points on the chart with scaling hp, so at full throttle it would seek its way to the greatest hp output.

Hard to describe in 500 words or less, but I understand myself so it must be possible

[extragoode]

I agree with Matt 100%! CVTs are great, in concept, but all the stupid people of the world that think they need to jackrabbit everywhere have made the execution way off target for efficiency. They're capable of being lighter, smaller, more efficient, more quiet, and have a wider total spread of ratios compared to a geared transmission regardless of all the available ratios in between min and max. The ONLY disadvantage I see them having is the slightly limited torque handling which could make low speed, high ratio driving difficult/a little less efficient/damage the trans, but I'm talking <20mph, top gear/ratio/whatever. I can also kind of understand the weird sensation of watching the speedometer rise and not the tach, but I would think the hoards of drones that have been driving mushy automatics forever would be used to this. I, being a 12 year veteran of the 5 speed, automatically think "Great, there goes my clutch!" This is just something that will seem more natural with time for me and the rest of society. I don't understand why the programming on the CVTs is fixed. Sports cars have buttons for their automatics that allow them to shift quicker. I don't even need manual slide ratio control like Matt wants even thought that would be sweet! All I need is a button (like sport shift or 4wd) or a selector (like the knob that chooses defrost or floor, does any vehicle use those anymore) that would let me choose "granny" mode or "lead-footed idiot" mode and maybe even another option in between. That's what it would take to get me out of my manual.

Anything that's programmed for the status quo and unchangeable is not for me, because I am not the status quo and I don't think anyone else here is either. If someone here is satisfied with the status quo why are they on a modding website of any kind?

[DifferentPointofView]

The ONLY disadvantage I see them having is the slightly limited torque handling which could make low speed, high ratio driving difficult/a little less efficient/damage the trans, but I'm talking <20mph, top gear/ratio/whatever.

"have been proven to support any amount of torque in production vehicles, including that used for buses, heavy trucks, and earth-moving equipment."

New CVT's use advanced lubricants that allow them to do this. Tractors now Use CVT. Old CVT's before 2005 had the low torque problem, but that has now been fixed.