I was just browsing the Hybrid Civic Forums and a user there had some questions about the CVT tranny that's in those cars. A poster linked to http://auto.howstuffworks.com/cvt.htm and I read up on it. I'm wondering why isn't Toyota using this type of transmission in their cars? It seems it makes for a very smooth ride. What are the cons for this type of transmission and will it last as long as a traditional one?
Why bother upgrading non-hybrids? It's a good example of "too little, too late". Toyota has a better CVT (the "Planetary" type, the heart of the hybrid system) that they'll be offering for all of there passenger vehicles within the next few years.
Actually the belt system does scare me. I wonder how long will it last before it pops? I'm going to do more research on it but at first glance it seems really neat. I'll probably test drive a car with CVT just to see how it feels.
In driving my '06 (about 1000 miles so far), I've had the sense a number of times that the tranny has just shifted in the good, old-fashioned way. Is that a figment of my imagination, or does the transmission lurch a bit under certain conditions as it changes ratios?
The Prius doesn't have any gear ratios, it's permanently fixed. The variable torque is provided by the electric motor, since it has high torque at low speeds, oppposite a gas engine (which has greater torque at higher RPMs) If you feel a lurch, it may be the gas engine being engaged/disengaged. Many articles report this isn't seamless, and feels like an auto trans shifting. The difference is it isn't linear to vehicle speed, it occurs at different times depending on other factors.
I've been through enough farm machinery to be wary of a Vbelt that's supposed to last 250,000 miles. Don't pull anything and don't put the foot to the floor and try to accelerate fast. All belts slip... at least a little... how much slipping (lot's of whomping on it, or tons of miles) before it's glazed over or worn out? Belt technology has come a long way, but... that far? Interesting...
I Had a HCH with CVT for 3 years before recently getting an 06 Prius. Although the Prius transmission is technically superior, the HCH provided a very smooth ride at all speeds. Actually it was a little better than the Prius in this regard because the ICE was always running before the car could move. For the Prius, the ICE turns off and on frequently and can be heard and felt slightly when this occurs.
Try the following vehicles: Saturn VUE, HCH, Audi A4 Multitronic, Nissan Murano, Ford Five Hundred to name a few with CVT. The Murano has 7 virtual gears for those times you wanna shift. Why? who knows.
Was that coke sized picture of the PSD the $4000 part that failed in another thread? When my Chrysler minivan transmission failed, it was less that 2K for a new one installed.
What do you mean by the first sentence above -- that there's a fixed ratio from the ICE to the wheels? Or that the ratio to the electric motor is fixed, with the motor then driving the wheels?
no what has failed in that Prius is that there is a short in the winding of the drive motor or the generator, MG2 MG1 respectivly, that burnt out the Inverter assy. The transmission/PSD unit is only serviceable as a unit. That's the reason for the High$. It includes new a drive motor and generator and the PSD and reduction unit and case, all one big piece. This would be compareable to replacing the motor and tranny in a conventional vehicle.
the transaxle in the Classic P111 has a reduction ratio of 3.905 to 1 with MG2 the G2 transaxle P112 has a reduction ratio of 4.113 to 1 with MG2 MG2 is what drives the car as it's directly connected to the ring gear of the PSD and the drive chain goes to the reduction gears in the transaxle housing before driving the carrier gear that drives the axles. The different ratio is to compensate for the different tire diameters on the two cars. Both cars have the same top speed or with in a mile per hour or two.
The Prius transmission consists of gears (and one chain) which are *always* engaged, but the magic of a planetary gearset allows the effective gear ratio to be varied over a wide range, depending on the speeds at which the engine and one of the electric motors are allowed to turn. See http://www.cleangreencar.co.nz/page/prius-technical-info (Contributor Graham Davies once had a very excellent explanation with animations of how the power split device works, but his site has gone dead.)
Honda's CVT is smoother only when the ICE isn't turning on and off all the time. I've driven 199K miles on the 1996 version of their CVT and it is already failing with 'slipping'. This means one time on the freeway, I couldn't get the car moving at freeway speeds until under 4K rpm, and then the tranny would still 'lurch' like it was a slipping clutch or something. Many a times, it cannot idle properly and will stop the engine unless I keep rpms above 1K (may be related to the 2nd cracked exhaust manifold). The dealership has explored it and said there metal debris in the oil pan. I've been complaining about it since 75K miles. $6K total to fix out of the dealership because Honda only allows full swaps; no spare parts. The post-1997 CVT is supposedly better, as well as a new one post 2001, but Honda already broke my trust.
