honda jazz (1 Viewer)

[s.m.i.t.h]

can someone explain to me what the feature 'CVT with 7-speed sequential shift and grade logic' in the automatic honda jazz actually does/mean?

 

[011]

shit, 7 speed CVT in a jazz? thats nucking futs

i think it also has EBD, BA and so on...

those japanese sure know their technology!

 

[DaddyK]

7 speed auto is fucking rediculous. Where are the good old days of just drive!

 

[DaddyK]

about about 5 years.

 

[DaddyK]

I don't have my p's yet...but whats that got to do with anything?

 

[breaking]

about about 5 years.

and your dads a cop

0mg corruption!1

 

[braad]

shit, 7 speed CVT in a jazz? thats nucking futs

i think it also has EBD, BA and so on...

those japanese sure know their technology!

the Jazz would probably need it too, being a small car that seems to be able to swallow a fair amount of crap (i.e. luggage) and weigh itself down, Maybe it helps in that respect too (esp. the grade control). maybe.

 

[bowman]

some of the newer cars are bringing out 8 speed, 12 speed an even 16 speed cars
this is for a smoother ride and for better fuel consumption

 

[braad]

some of the newer cars are bringing out 8 speed, 12 speed an even 16 speed cars
this is for a smoother ride and for better fuel consumption

wtf?? where'd you hear that? seriously, i never knew

 

[bowman]

my dad's an enginer, an his mates were talking about it
not to sure about that
but they are trying to do this


my dads old work mate helped design the 4speed auto (a variation of it). very smart man this dude is. he knows his shit

 

[braad]

i suppose it'd be possible, as gears are really just in relation to each wheel, so yeh...hmmm

interesting, if it's real, keep us informed!!

 

[011]

Didnt a special skyline in the past have 8 gears or something?

 

[s.m.i.t.h]

k thanks dude
so all in all is a honda jazz worth it then?

 

[ITJ]

I have a Jazz as a second car and I gotta say that despite being fairly ugly, its the most practical thing I have ever seen. Its got 4 doors and can swallow a huge amount of stuff and carry 4 people with plenty of room, (which is unlike the Porsche Boxter I am buying to replace my other car). The fuel economy is amazing, especially with the CVT auto. In fact, this transmission is so efficient, its actually faster and uses less fuel than the manual Jazz.

To answer the question at the start of this thread, a CVT is a continuously variable transmission. It theroretically has an infinite amount of gear ratios which allow the box to select the optimum gear ratio to suit and thus make the most out of the engines power and maximise fuel economy. The Jazz CVT, at least on the VTI and VTI-S models also has 7 predefined ratios or gears, controlled by steering wheel buttons, if you want to have a little fun shifting yourself. Grade logic is a feature that is appearing on many automatic gearboxes and is a program within the electronic "brain" of the gearbox. It senses the degree of incline you are on and adjusts the gearboxes shift points to ensure that it is in the correct gear for the conditions. Older auto gearboxes often caused the engine to labour in too high a gear going up a hill, needing you to kickdown or manually shift down, or hunt between gears (constantly shifting up and down) or go in too high a gear going down a hill.

 

[Bob.J]

don't forget it costs a SHITLOAD of money just to get the damn car serviced

it's not really worth the money. You're paying for the badge

 

[seremify007]

my dad's an enginer, an his mates were talking about it
not to sure about that
but they are trying to do this


my dads old work mate helped design the 4speed auto (a variation of it). very smart man this dude is. he knows his shit

I don't know about the 12/16 speed transmissions in production vehicles, but the best I've heard is the new Lexus has the first 8-speed transmission fitted to a consumer vehicle (ie. not a truck).

Back on topic to the 7-speed-CVT; a CVT is a continuously variable transmission. Hypothetically, and iirc, the engine can drive as if there were no gear changes at all (it'd be so perfectly smooth) but for peace of mind to the Americans, they purposely put in an artifical 'shift' to make it feel more powerful. As for what's so good about it? It's incredibly fuel efficient and is lightyears more advance than the 4-speed automatic. When the car is quite low on power, having a well-matched transmission can be a saviour.

What Bob J said is true, Hondas are expensive to service and require servicing more regularly than a lot of other cars in the price range... but the Jazz is a very great little car. However in that price range, I'd probably go the Yaris (and spec the safety pack) over the Jazz.

 

[loquasagacious]

Seremify and ITJ have pretty much nailed down the basics of a CVT. That is the continuously varying ratios (an old idea only recently becoming doable because of advances in technology). And correctly highlight the gimmicky nature of the 'seven speeds', that is they are just pre-sets which give the illusion of a conventional change because it is a pretty big thing for drivers to get around the idea of having no gears.

To my knowledge only three cars on the market have CVTs available: the Jazz, Mini and Audi A8.

Turning to the 8, 12 and 16 speed boxes bowman is talking about:

There are production vehicles with this many gears - trucks.

I highly doubt we will even see more than a 7 speed manual in mass cars.

Autos it becomes a new game though. Has everyone here noticed how the gearing on mountain bikes work? eg a 21 speed bike has three gears at the front and 7 at the back? And of course 3x7=21, and thats the yr9 maths showing the total number of possible combinations.

Ford in Europe has developed (or is developing) a nine-speed gearbox based on this principle. eg it is infact two three speed gearboxes (3x3=9). Similarly a 12-speed would be a 3 and a 4 and a sixteen a 4 and a 4.

For the more mechanically minded: It's remarkably simple and clever:
Engine----drive--->gearbox 1---->gearbox 2---->diff---->axeles--->wheels.
And as the more perceptive will have realised this has been mechanically possible for a very long time, and is fact the basis behind 4wds which have two gearboxes eg 5 speeds in a conventional box and hi and low range in a transfer case. Making a handy ten speeds. However as I'm sure you've noticed not too many people drive around in their 4wds using ten gears and two gear sticks. Its too bloody hard, hence the concept of the joined boxes has only become realistic with the advent of computers smart enough to work out which combination is the best to use.

Realistically though while this is very clever in its own right it is only momentarily prolonging the inevitable demise of the gearbox as we know it. CVTs are the way of the future and then theres the whole electric car issue which opens another kettle of fish.

 

[seremify007]

There are CVTs in a few more cars (from those manufacturers)... can't quite remember which ones for sure though! IIRC don't hybrids (ie. Prius/Civic) use CVT too?

I think even a 7 speed manual is starting to get a tad on the hectic side...? I am inclined to think these transmissions with more gears are better suited to clutchless or more advanced transmission modules found in luxury/premium cars?

 

[petar13]

In fact, many new cars have a CVT - the Nissan comes to mind (was it the Maxima, or the other one?). Many new (comparatively) cheap cars from the East are boasting a CVT.
There is no 7 speed manual (single) transmission with a (conventional) clutch currently existing. I think the M5 gearbox is as close as you can get - however even that is missing the clutch pedal, even though the internals are akin to a manual box.

 

[seremify007]

CVTs are pretty good because of their fuel efficiency aye? Maybe that'll make them become more widespread in the future as an alternative to companies having to find other ways to save petrol.