https://www.youtube.com/embed/x3UpBKXMRto
Yes, that Williams tested the use of a continuously variable transmission--the bane of many automotive enthusiasts--back in 1993. As crazy as it may sound today, their logic was sound: the CVT could keep the engine in its peak power band while minimizing inertial changes normally associated with a more conventional gearbox.
I had a 1985 Polaris 250cc 4-wheeler with a CVT in it that lasted 30 years before it finally tanked and it was impossible to find parts for to fix. Not sure why it's deemed to be such new/novel idea. I did hate that 4-wheeler as a kid for the exact reason of not being able to hear it shift through gears :(. On an F1 of that era it's pretty cool.
CVTs don't break any more than any other automatic transmission. To me most of their bad reputation is because they aren't as familiar as the more conventional auto transmissions. Yes, they are weaker...but that doesn't matter for factory applications...they are also about 100 times simpler to rebuild. I wouldn't want a car with a CVT transmission....just like I don't want a car with any automatic transmission...they are all garbage that will fail much sooner than a manual transmission....good for consistency...but bad for me.
I'm also not entirely opposed to CVTs. In fact, most of my issues with it are just in how it's done. The thing about peak power is definitely possible. My old 340hp Lexus GS450h accelerated more like a 380-400hp car because it DID just sit at peak power, whereas most 340hp cars are only 340hp for a few hundred rpm and then drop to probably 270 after every shift. The closest things in weight and power to it were Hemi chryslers. It was faster than a regular 340-370hp Hemi car and only slightly slower than a 425hp 6.1 car. Doing the cvt action with an electric motor and a planetary gearset is almost bombproof and gives you torque fill at the bottom of the range where most CVTs suck.
The lowest ratio the CVTs can hit is usually one of my biggest problems with them. CVTs are only variable within a range, and usually the lowest ratio they can achieve isn't low enough in my opinion. There's also the issue of start clutches and how i sort of hate them. Now manufacturers are finally getting around these problems by hooking the CVT in series with 2-spd gearboxes, and giving them a torque converter. All stuff which addresses my dislikes.. but still isn't as good as a Toyota hybrid 'e-cvt'. If Lexus would do with the LC what they did with the old LS600hl and put the hybrid trans behind their wonderful 5.0l V8, it would become a dream car for me.
And just a few years ago many on this board, including myself harped on automatics. But, some of us have come around. Heck, when searching for my NC, I specifically wanted the automatic.
Challenges with cvt that mave made it new and more recent have to do with power capacity. Rubber belts on snowmobile and 4 wheeler applications are ok, but putting 200+hp and expecting it to last 100,000miles...
New automotive one use metal belts that are like a stack of coins and operate on compression rather than tension like the rubber belts. There were still teething pains, Nissan had a lot of challenges with warranty rates.
I have a f500 that I have been autocrossing, I understand that many hate the sound, but it's actually fantastic to drive.
In reply to DirtyBird222 :
DAF had it in a small sedan back in 1958.
Wicked93gs said:CVTs don't break any more than any other automatic transmission.
As an ex-Nissan service advisor, I beg to differ.
In 95 the Honda Ferio VI-RS came out with a cvt.
The only experience I have with them is on scooters where they work really well. Loaded weight is what 400lbs if that.
4000lbs vehicles, I will let bigdaddylee82 speak on the track record for those :P
bigdaddylee82 said:Wicked93gs said:CVTs don't break any more than any other automatic transmission.
As an ex-Nissan service advisor, I beg to differ.
CVTs that are not in Nissans don't break any more than any other automatic transmission, then.
In Mopars and Subarus, they just work. Change the yummy expensive fluid every 60k and they are fine.
The only time I had issues with one was a Patriot that someone had put ATF in, and the trans didn't like that. I changed the fluid twice with the correct fluid and it was fine.
The Nissan thing is overheating IIRC. But a vacation loaded Rogue chugging up the grapevine is going to generate a lot more heat than a 2500 pound civic with a 1.5 no torque wonder. If they fitted a big ole cooler the Nissan cvt would have a better rep
Knurled. said:bigdaddylee82 said:Wicked93gs said:CVTs don't break any more than any other automatic transmission.
As an ex-Nissan service advisor, I beg to differ.
CVTs that are not in Nissans don't break any more than any other automatic transmission, then.
In Mopars and Subarus, they just work. Change the yummy expensive fluid every 60k and they are fine.
The only time I had issues with one was a Patriot that someone had put ATF in, and the trans didn't like that. I changed the fluid twice with the correct fluid and it was fine.
Yes, in Subarus they work. Do they work well? thats a good topic for discussion. the three Subarus my kids mom has owned that have them, the cvt has been a constant hemroid in daily driving. Nothing that will keep the car stranded or at the dealer for lengthy repairs but lots of annoying things that make it a nuisance to drive almost. Bucking at low speeds, a mind of its own, lunging, and so on.
Our new Fit has one & overall I'd describe it as "transparent", as in I rarely notice it.
The two things I have noticed is sometimes when accelerating reasonably hard from a light & then letting off, it will hang a second before "upshifting".
Also, our street is under construction & a couple times it has left us with a pretty steep ramp up into our driveway. When backing in slowly I damn near have to floor it to get the car up it.
I absolutely love CVT transmissions when paired with cruise control and a 4 cylinder. In the land of rolling hills, allowing the engine to slide smoothly up and down the rev range is so much better than the constant jumping between gears that I'm used to. Regular automatics are still more fun to drive, but a CVT does its job really well. I'm really curious what a CVT driven Miata would be like. I bet it would still be quite fun.
I have a single seat race car (F500) with a CVT drivetrain and there are so many advantages that I can say I'm not missing the joy of hearing the motor shift. It's especially advantageous for autocross. As for track work I've done one track day with it, I'll be doing a vintage race with the car in a couple of months but I suspect I will like the CVT for road racing as well.
For a competition car it's nice to not have to worry about being stuck between gears (motor revving to much in second but bogging in third) and if you do have an issue, you simply make adjustments to the spring positions or change the flyweights. No need for a $$$$$$$ close ratio gearbox.
For a road car I'd prefer a manual; as it gives me something to do.
Watching Coulthard's summary, I'm so curious about how it drove.
I know I'm behind the times in the automatics I've driven, and I've test driven one CVT IIRC, but it's so rare to drive one that doesn't seem to insert a bunch of mush between the throttle pedal and the drive tires. Recent BMWs have given me some hope, but most of the time it just feels like there's that question of intent, and if the trans doesn't know that I just want to adjust the weight real quick-like, or squirt between cones momentarily, it'll spend the entire duration of time I meant to be gassing it chewing on finding me a lower gear for the big acceleration that isn't actually about to happen.
It does seem like a well-programmed CVT could work nicely hand in hand with that modern engine management concept of throttle position as "torque request." Give me my request by dialing the engine to the output I want as closely as possible at the current ratio, then start feeding out gear reduction if we can't get all the way there, but don't reduce the ratio faster than the crank's accelerating... The math should be totally doable to combine the engine map with the available gear range to be as "crisp" in acceleration as a manual.
You'll need to log in to post.
