10th Honda Civic Forum banner

1 - 17 of 17 Posts

·
Registered
Joined
·
28 Posts
Discussion Starter · #1 ·
I had a general idea how CVT worked ..no gears .. just pulleys .. but this is a good find

 

·
Registered
Joined
·
213 Posts
I've driven a CVT since '98 (Civic HX) and won't have another. The new ones are advertised as getting better mileage than the 6MT, but I don't buy it. According to the engineers, the most efficient transmissions (X input vs Y output) are:

Single-speed manual transmission 99%
Multi-speed manual transmission 96% - 98%
Toroidal CVT 93% - 94%
Belt CVT (like mine) 91% - 92%
Old school hydraulic autos 89%

Why do CVT's require oil/fluid? Not for lubrication (belts don't need lubing), but for cooling. Think about that...some of the energy is transformed into heat instead of torque. In a manual transmission, using gears, the oil is really only for lubrication to reduce friction losses. That's why CVT's are typically 100 lbs. heavier than the manual. OK, I'll get off the soapbox.
 

·
Registered
Joined
·
28 Posts
Discussion Starter · #5 ·
I've driven a CVT since '98 (Civic HX) and won't have another. The new ones are advertised as getting better mileage than the 6MT, but I don't buy it. According to the engineers, the most efficient transmissions (X input vs Y output) are:

Single-speed manual transmission 99%
Multi-speed manual transmission 96% - 98%
Toroidal CVT 93% - 94%
Belt CVT (like mine) 91% - 92%
Old school hydraulic autos 89%

Why do CVT's require oil/fluid? Not for lubrication (belts don't need lubing), but for cooling. Think about that...some of the energy is transformed into heat instead of torque. In a manual transmission, using gears, the oil is really only for lubrication to reduce friction losses. That's why CVT's are typically 100 lbs. heavier than the manual. OK, I'll get off the soapbox.
Yep .. probably some validity to your points.

A guy I ride with owned a Prius. 8 year 80k on the belt .. traded.

Same guy has a .. Rogue. 65k on the belt before needing replacement. He did tow light loads ..his bikes .. $200 repair.

I like those numbers.
 

·
Registered
Joined
·
12 Posts
Everybody I know is so hyped about CVT. I mean, there's gotta be something to it if you have to pay more money to have it in your car right? But I agree it may not fit everyone. Again, best to see if you get a test run in a car that has it to see if it works for you!
 

·
Registered
Joined
·
24 Posts
I can only imagine the wear and tear that the rubber belt is going through and that's inside cars.
The CVT in the video isn't anything like they type that is used in cars. I was researching this the other week. That is the type of transmission you'd see in a snowmobile. Cars have metal plates around a wire band. There are much better videos on youtube that show how the CVTs in cars work.

The band in our cars looks like this:



Why do CVT's require oil/fluid? Not for lubrication (belts don't need lubing), but for cooling. Think about that...some of the energy is transformed into heat instead of torque. In a manual transmission, using gears, the oil is really only for lubrication to reduce friction losses. That's why CVT's are typically 100 lbs. heavier than the manual. OK, I'll get off the soapbox.
Wow thats some conclusion you have there. Its almost funny because it shows you have no idea how CVTs work. I'm not trying to be a dick, I just don't know how people can be so confident as they make **** up. I mean I'm just a guy that researched this as a hobby. Your CVT would tear itself to shreds from friction within a month if it didn't have fluid. There are two pullys inside a CVT. The belt rides the sides of these pulleys. When one moves it's sides further apart the other moves it's sides closer together. The metal band is V shaped as well and moves up and down the sides of the pullys and thats how you get different gears. The fluid in CVTs is a special kind that allows the metal band to slide up and down on a sheen of the fluid rather than having metal touching metal. Here is a picture of a CVT belt with wear on the sides from sliding up and down:

 

·
Registered
Joined
·
213 Posts
The CVT in the video isn't anything like they type that is used in cars. I was researching this the other week. That is the type of transmission you'd see in a snowmobile. Cars have metal plates around a wire band. There are much better videos on youtube that show how the CVTs in cars work.

The band in our cars looks like this:





Wow thats some conclusion you have there. Its almost funny because it shows you have no idea how CVTs work. I'm not trying to be a dick, I just don't know how people can be so confident as they make **** up. I mean I'm just a guy that researched this as a hobby. Your CVT would tear itself to shreds from friction within a month if it didn't have fluid. There are two pullys inside a CVT. The belt rides the sides of these pulleys. When one moves it's sides further apart the other moves it's sides closer together. The metal band is V shaped as well and moves up and down the sides of the pullys and thats how you get different gears. The fluid in CVTs is a special kind that allows the metal band to slide up and down on a sheen of the fluid rather than having metal touching metal. Here is a picture of a CVT belt with wear on the sides from sliding up and down:
Kyle, as the owner of a Honda CVT since '98, I can assure you that I know exactly how a CVT works...I researched it before I purchased the car. I also know, from experience, how much replacement fluid it takes for my CVT (about 7 qts), compared to the fluid in a manual transmission (about 2 qts). Your comment above about "tear itself apart from friction" "if it didn't have fluid" proves my point. CVT's are simply not as efficient as a manual, and create much more heat from friction, requiring more fluid/lube/coolant or whatever than a manual. I can only assume you understand that frictional loss, is a loss of efficiency...trying not to be a dick.
 

·
Registered
Joined
·
24 Posts
Why do CVT's require oil/fluid? Not for lubrication (belts don't need lubing), but for cooling.
You say there is no friction and belts don't need lubing. You are completely wrong. All you would need to do is watch a video on YouTube about how CVTs work to understand this. Owning a Civic in 1996 does not give you this knowledge. The sides of the belts are constantly sliding up and down the sides of the pullys. The rotating shafts and gears also produce friction.

Then you go on to say that they are bad at producing torque because they are making heat. Also, not true. CVTs are better at producing torque because they have an infinite number of gears and can always be in the gear that produces optimal torque. A regular automatic is always drifting under and over the optimal torque mark because it is stuck in a fixed gear and can only go in the gear that is closest to that point. This is why CVTS get much better milage.
 

·
Registered
Joined
·
876 Posts
The CVT in the video isn't anything like they type that is used in cars. I was researching this the other week. That is the type of transmission you'd see in a snowmobile. Cars have metal plates around a wire band. There are much better videos on youtube that show how the CVTs in cars work.

The band in our cars looks like this:



Wow thats some conclusion you have there. Its almost funny because it shows you have no idea how CVTs work. I'm not trying to be a dick, I just don't know how people can be so confident as they make **** up. I mean I'm just a guy that researched this as a hobby. Your CVT would tear itself to shreds from friction within a month if it didn't have fluid. There are two pullys inside a CVT. The belt rides the sides of these pulleys. When one moves it's sides further apart the other moves it's sides closer together. The metal band is V shaped as well and moves up and down the sides of the pullys and thats how you get different gears. The fluid in CVTs is a special kind that allows the metal band to slide up and down on a sheen of the fluid rather than having metal touching metal. Here is a picture of a CVT belt with wear on the sides from sliding up and down:

This is why the whole logic of K.I.S.S (keep it simple stupid) works here, parts are moving, metal parts, similar to how your engine works and if it requires lubrication to run properly so does this CVT transmission and transmissions overall, and naturally with that comes some level of cooling :D
 

·
Premium Member
Joined
·
419 Posts
CVTs are better at producing torque because they have an infinite number of gears and can always be in the gear that produces optimal torque.

Wrong, the CVT is set up to give you optimal rpm's for fuel economy. To get torque out of the 1.5 you must increase rpm's and create boost for the turbo. Once you have your foot into it it's great at making torque but not so good at economy.
 

·
Registered
Joined
·
213 Posts
This is why the whole logic of K.I.S.S (keep it simple stupid) works here, parts are moving, metal parts, similar to how your engine works and if it requires lubrication to run properly so does this CVT transmission and transmissions overall, and naturally with that comes some level of cooling :D
Yep...about three to four times more than a manual. I just don't understand why some are so myopic about the CVT, when the direct connection through gears and clutch is much more efficient than having belts or hydraulics between the engine and driven wheels. Few Americans today can do the "three pedal dance" (overseas the manual is more popular), and some that can, still prefer the car do the shifting for them. I'm glad I cut my teeth on MGB, Triumph GT6+, and an Austin Healey 3000 MKIII!
 

·
Registered
Joined
·
24 Posts
Wrong, the CVT is set up to give you optimal rpm's for fuel economy. To get torque out of the 1.5 you must increase rpm's and create boost for the turbo. Once you have your foot into it it's great at making torque but not so good at economy.
I'm not talking about the maximum torque the engine can produce. I'm saying a regular automatic has a small window to produce optimal torque for the gear it is in:



Our car's CVT causes the torque to stay much more constant regardless of the gear it's in. (first graph below)

 

·
Registered
Joined
·
1,587 Posts
I'm assuming the left graph is the CVT since there's less of a torque slope? I'd prefer constant torque over optimal torque.
 

·
Registered
Joined
·
382 Posts
well, b20, you are correct. however, the graph on top shows the max torque in a standard automatic (Non-CVT).
 
1 - 17 of 17 Posts
Top