Says something about how Toyota transmissions are different from other CVTs. I'm still not sure why my 250,000 mile Corolla still shifts like new. Mentions something about having an additional starting gear that other brands don't.
CVTs explained video
- Thread starter atikovi
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Says something about how Toyota transmissions are different from other CVTs. I'm still not sure why my 250,000 mile Corolla still shifts like new. Mentions something about having an additional starting gear that other brands don't.
I must run now but am looking forward to watching this. TIA.
It is true that the Toyo CVTs are designed with a starter gear that helps reduce wear on the chain. But think about this in a common sense way. Why do you have to add something to an intial design to prevent wear? You do it because the initial design has shortcomings or is flawed from a manufacturing standpoint.
Remember the shear design of these transmissions mean that they are going to have more metal to metal contact and thus wear and increased necessary maintenance. CVTs were an attempt by OEMs to solve for two issues at once....... 1. Increase MPG from engines by keeping them in a relative narrow power band limit, and 2. Do it for less cost as compared to conventional automatic transmissions of the period.
Remember the shear design of these transmissions mean that they are going to have more metal to metal contact and thus wear and increased necessary maintenance. CVTs were an attempt by OEMs to solve for two issues at once....... 1. Increase MPG from engines by keeping them in a relative narrow power band limit, and 2. Do it for less cost as compared to conventional automatic transmissions of the period.
I thought Toyota was using launch gear to get deeper gearing? CVT has been limited in total gear ratio range. Since mpg is paramount, it is going to be tall geared for best mpg / lowest rpm at cruise, so takeoff suffers. By introducing a conventional gear, they can get deep gearing for taking off, perhaps run the CVT on top of that, then shift into high range (the video makes it sound like it's strictly lowest ratio in CVT, then shifts the gear, then runs on CVT--but I'm not convinced the video gets all details correct).
The D-CVT is interesting. That's applying a direct drive ratio at cruise. Pretty cool. Problem is, or the problem that I think might exist, is that the ratio required at cruise is not necessarily a constant. A torquey engine won't care, but my low output cars do... as I go driving around in our rolling hills, my rpm is never quite a constant. D-CVT sounds like a way to get utmost mpg on paper, maybe not so in the real world. I wonder if Atkinson engines, which might have a more narrow rpm range, would not like this D-CVT, but it might work well with older engines that have a wider torque range. Pure conjecture on my part.
atikovi, your 250k Corolla, that's a 2017 I thought? The video said Toyota came out with the direct launch in 2018. So does your Corolla have the direct launch or not? I want to say, if it's a 1.8L then it's conventional CVT, if it's a 2.0 then it has the direct launch. I know my 2021 Corolla has the 1.8L and conventional not direct launch.
Having launch gear might help with longevity, not sure, by being able to apply gear reduction / torque multiplication after the CVT section might help limit amount of torque through the rubber band? But Nissan, despite all their problems, seems to have had a V6 with a CVT that managed to live. Maybe they have a narrow gear ratio range and that leads to better torque handling? pure swag on my part.
The D-CVT is interesting. That's applying a direct drive ratio at cruise. Pretty cool. Problem is, or the problem that I think might exist, is that the ratio required at cruise is not necessarily a constant. A torquey engine won't care, but my low output cars do... as I go driving around in our rolling hills, my rpm is never quite a constant. D-CVT sounds like a way to get utmost mpg on paper, maybe not so in the real world. I wonder if Atkinson engines, which might have a more narrow rpm range, would not like this D-CVT, but it might work well with older engines that have a wider torque range. Pure conjecture on my part.
atikovi, your 250k Corolla, that's a 2017 I thought? The video said Toyota came out with the direct launch in 2018. So does your Corolla have the direct launch or not? I want to say, if it's a 1.8L then it's conventional CVT, if it's a 2.0 then it has the direct launch. I know my 2021 Corolla has the 1.8L and conventional not direct launch.
Having launch gear might help with longevity, not sure, by being able to apply gear reduction / torque multiplication after the CVT section might help limit amount of torque through the rubber band? But Nissan, despite all their problems, seems to have had a V6 with a CVT that managed to live. Maybe they have a narrow gear ratio range and that leads to better torque handling? pure swag on my part.
That was an iM. Now have a 2020 Hybrid.
Thanks for posting! 
As long as the CVT performs the way they’re supposed to, I love them.
When working this way, they just go about their business.
As long as the CVT performs the way they’re supposed to, I love them.
When working this way, they just go about their business.
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Ah. That'd be an e-CVT then, no belt. Won't say they never wear out. But they have like 7 moving parts, and no frictions, and no belts. Not known for being a wear item, even when neglected.
Those seem to be the best CVT system with the bonus of being a hybrid, and potentially best overall transmission, if it can fit into a vehicle. Large field tractors use the same style of CVT but use a hydraulic motor instead of an electric to vary the ratios.
Maybe there is some limit on the electric motor side that prevents this system from being used in pickups or larger trucks as the rest of it should be scalable to any amount of torque or hp?
I'll admit I was really wrong with CVTs for a long time. I've grown to like them.
I feel I have an understanding of the reliability concerns well enough to even trust them now.
I will say - I don't like how our Nissan CVT fakes shifts. Ironically, the computer goes to lengths to hide the actual low/hi shift.
I feel I have an understanding of the reliability concerns well enough to even trust them now.
I will say - I don't like how our Nissan CVT fakes shifts. Ironically, the computer goes to lengths to hide the actual low/hi shift.
I will say, I've grown to almost like the CVT I have in my Corolla. No launch gear, feels a bit laggy off the line. But driven sedately the car is rather unobtrusive. Far from luxury but is indicating 40mpg if I do my part, on summer gas.
When I have my foot in it, it'll fake shift, not sure if it's 100rpm drops or what, but just enough that it "feels" right. The rest of the time, it's a rubber band but really not that bad.
The e-CVT in our hybrid is really nice, although I wish for just a hair more NVH reduction on engine start. Far from bad but just enough to let me know I didn't pay extra for the Lexus I guess.
When I have my foot in it, it'll fake shift, not sure if it's 100rpm drops or what, but just enough that it "feels" right. The rest of the time, it's a rubber band but really not that bad.
The e-CVT in our hybrid is really nice, although I wish for just a hair more NVH reduction on engine start. Far from bad but just enough to let me know I didn't pay extra for the Lexus I guess.
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