Transmission Activity

If you put it in 4, will it ever downshift into 3 by itself? When you
shift into 3 does it effectively double clutch?

Well, as you point out, I don't have any experience with modern high
end luxury cars, but I note that at least more modest cars generally
have a significantly greater 0-60 speed and a lower mpg rating. Since
they now mostly have five gears, I would assume that means they are
slipping. Actually, the slipping is partly by design, the so-called
torque multiplier effect. Basically, if you are cruising along and
you give it a little gas, but not enough to force a downshift, you
will see the rpms jump up immediately.

The ultimate "torque multiplier" is a CVT. A lot of people don't like
them at all, but others say they get used to it. (The perception
problem is so bad that some manufacturers program virtual gears into
them thereby defeating the chief advantage of the CVT.) I only rode
in one CVT car, a Nissan luxury sedan in Japan and it wasn't bad in
that application. He drove it fairly aggressively too - we hit almost
180 kph on the expressway. I would like to try one of these. I don't
know if I would like it or not.

Will it let you start out in 5th gear? Not that I want to do that,
but the point is I don't like it downshifting or upshifting without my
command.

Well, I would certainly prefer an MT to the AT in my 98 Ody, but of
course that was not an option.

Perhaps newer, high dollar vehicles are better set up for manual
shifting, and have fewer compromises but then that raises the point:
Why not just have an MT? They are cheaper, more durable and I like
the way they work just fine. For my purposes and preferences, I see
no benefit to an AT whatsoever.

I presume I will never again be able to buy a large, cargo carrying
vehicle (eg. my old Volvo 245 station wagon) with an MT so I assume I
will have to go with 2007 technology sooner or later. I will let you
know what I think.

I would first point out that torque converters are not banned AFAIK,
but they are not used either. I would be curious to know whether and
how ATs would be used in F1 if they were not banned. I can imagine
the programming: if rpm >= redline then upshift, if downshift RPM <
redline then downshift. The situation is a little different on the
road and the technology is bound to be different and more compromised.
I seem to recall Ferrari had an AT at one time in F1. I dont' recall
if it was a clear advantage but I do recall that on a couple of
occasions it decided to downshift into 2nd when it should have been in
5th. That was exciting. Not relevant to the argument but an amusing
story. It may have been an early paddle shifter rather than a true AT

 

yes, absolutely. it does it on "kickdown" acceleration /and/ it does it
on braking. not gentle braking, but harder braking.

pointless exercise on an automatic. but even then, on the modern autos,
in conjunction with electronic throttle, yes, the engine revs /are/
meshed to the gear on shift.

there's no slipping unless the lock-up clutch is released. see below.

yes, that's what a torque converter does.

that's because the lockup clutch is released to allow more torque. more
flexibility than a stick where you'd have to shift.

that's different - it's not a torque multiplier. if is however a great
way of achieving absolute optimum gear for all conditions.

absolutely! i drove a "real" cvt one when i was in europe years ago,
and yes it is /real/ weird at first. but it's amazing how much you can
get out of a small 2-cylinder engine when it's got perfect gearing.
quite fun! this particular model had 2 independent drives too, so not
only did you have optimum gearing, you had limited slip diff benefits in
snow & ice too.
http://www.ritzsite.demon.nl/DAF/DAF_cars_p2.htm

if you're not used to traditional automatics, the transition is easy.
if you're used to traditional autos, its weird for a few minutes because
it doesn't "shift", but beyond that, they're actually very impressive.

no, but it'll start in 2nd. mine will anyway. useful in snow.

regarding shifting, it'll shift down any time on command, providing
doing so doesn't over-rev the engine - it won't let you do that.
regarding up-shifting, you can hold it back until you're ready, and even
then, it'll wait until it's certain you mean it - if you have your foot
down. if you're not driving hard, it's academic.

i used to think that. then i had a knee injury that prevented me
driving a stick for some months, so i bought an auto. and every time
i've driven a stick since, it's been a real chore. that was nearly 20
years ago. it may be that there's some bad autos out there, but the way
i have my civic set up [the shift pattern is adjustable], the shift
points are pretty much dead on where i'd have them manually, and for
other stuff, i over-ride.

correct - they're heavy.

maybe a problem with the sequencing mechanicals? who knows.

i think in due course, semi autos will replace sticks. at least in
sports cars. they offer faster, more accurate shifting, and computer
control knows more about the potentials of the system than the driver
does a lot of the time. a friend has a tiptronic carrera - hold the
shift lever and put your foot down, and it'll select the lowest gear for
the speed to give fastest acceleration, and you can revert to auto from
there so it shifts up through in the fastest possible time. trust me -
it's fun!

 

It is not a bad thing, I just don't care for it. If I want to
downshift, I can do that. If I don't want to, I don't like the car
doing it on its own.

That is what I mean. I figured they had fixed that aspect which is
the worst part of the older ATs.

But that is the slippage. The engine speeds up races up ahead of any
change in vehicle speed. It is like a slipping clutch. As for more
torque (horsepower really) a lot of that is eaten up by the
inefficiency of the torque converter. On cars where you can get a MT
or AT with the same engine, the MT is almost always faster and gets
better mileage.

Neither is the conventional AT, it just has a clever design to let the
engine speed up ahead of the vehicle speed without shifting. It is
basically like a limited range CVT.

I agree that it has a big theoretical advantage, especially compared
to a conventional AT.

That was the original CVT. Do you remember who offered the first CVT
in the US. (I don't think they ever sold the Daffodil here.)

Again though, I am not sure they are any faster or more efficient than
a good MT. Consumer Reports tested the Versa with MT and with CVT.
The MT version was 0.6 seconds faster to 60 and got one more mpg. (And
CR panned that MT.) They also tested MT and (conventional) AT
versions of Fit, Rio, Accent and Yaris. In each case the MT was 2 - 3
seconds faster and got 2 more mpg, so the CVT was clearly better than
an AT but not as good as even a mediocre MT, at last on raw numbers.

And yet, there is hardly a proliferation of CVTs on the market. Most
of them seem to be on hybrids in fact.

I appreciate that many people prefer AT, and if you have a bad knee,
there isn't much choice. But I really enjoy driving the MT. I
haven't encountered an AT yet that I could actually say I enjoyed, but
I certainly haven't driven many new ones.

It was a computer glitch. As they say, to error is human. To really
foul things up requires a computer.

I am open to that, but it has to come down to Civic level before it
will have any relevance to me. I am sure that a Porsche would be fun
no matter what kind of transmission it has.

BTW, you might want to review my post in this thread from 2005:

http://tinyurl.com/ygpvay

I had no idea they would work that way, it just seemed like the
logical way to do it.

 

why not? it's just like you'd have on a stick.

but i don't understand the problem - what's wrong with it? engines are
not perfect across all rev ranges - why not let a computer manage the
efficiency curves - for that's what's happening.

how is a slipping clutch more efficient? [it's not.]

not so with the modern autos. and that's one of the big things about
honda autos - it's basically a standard transmission with clutch packs
instead of synchros. inherently more efficient than planetary gears.

no dude, they're totally different. "torque multiplier" is something a
torque converter can do - hence its name. everything else is ratio
control, be it continuously variable or discrete.

compared to /any/ transmission. there are mechanical efficiency issues
with the friction interface, but that is more than outweighed by ratio
flexibility and ability to keep the engine at its most efficient.

well, the daf was only 650cc iirc, and 0-30, that wasn't much to touch it.

that depends on the management system. the modern cvt's "simulate" gear
shifts which is the dumbest damned thing since it's not utilizing the
inherent benefit of the system! on that basis, i'm not surprised.

that's consumer and mechanic inertia - nothing to do with benefits or
reliability. trust me on that one - i've driven the daf for an extended
period and it's a great system.

indeed.

 

Interesting discussion I started here, I guess....!

I've driven the CVT in an Audi A4 loaner and thought it was weird at
first (as someone else noted). But it also had 'sport' settings where
it would 'shift' thru seven 'gears'. There are more CVT's out there
than you think - off the top of my head, I can think of the Audi (A4
non-quattro auto models), Ford Freestyle cross-over, and Nissan Altima,
Murano, Maxima and Versa.* I think some version of the Ford Five
Hundred has it as well. So, they are becoming more popular.

The best compromise seems to be the automated manual transmissions -
they are a true manual trans with an automated clutch. No torque
converter. ( http://en.wikipedia.org/wiki/Direct-Shift_Gearbox )
Audi's DSG is commonly considered the best example, although BMW has
one (whch regularly gets panned for poor auto shifting). Porsche may
have one as well. I've driven the DSG and it is excellent, very fast
shifting and a decent auto mode as well. But I still prefer a
conventional manual transmission.

For the Ody, I'm prefectly happy with an automatic.

*Oh, Wiki has a list of CVT equipped autos world-wide.

* Audi A4 2.0/1.8T/2.4/3.0/2.5 TDI
* Audi A6 2.0/1.8T/2.4/3.0/2.5 TDI
* Dodge Caliber
* Fiat Punto 1.2 L
* Ford Escape Hybrid 2.3 L 4 cyl
* Ford Five Hundred 3.0 L 6 cyl
* Ford Focus C-MAX 1.6 L TDCi 110 PS
* Ford Freestyle 3.0 L 6 cyl
* Honda Civic HX 1.7 L 4 cyl
* Honda Civic Hybrid 1.3 L 4 cyl
* Honda City 1.5 L
* Honda HR-V 1.6 L
* Honda Insight 1.0 L 3 cyl
* Honda Jazz 1.4L / Honda Fit 1.3 L/1.5 L
* Hyundai Azera 3.8 Lambda
* Hyundai Sonata 3.3 Lambda
* Jeep Compass 2.4 L
* Lexus GS450h 3.5 L 6 cyl
* Lexus RX400h 3.3 L 6 cyl
* Mercedes-Benz A-Class

* Mercedes-Benz B-Class
* Mercury Montego 3.0 L 6 cyl
* Microcar MC1/MC2 505cc 2 cyl diesel or petrol
* Microcar Virgo 505cc 2 cyl diesel or petrol
* Mitsubishi Colt 1.5 L MIVEC 4 cyl with INVECS-III CVT
(Asian-Oceanian version only, 72 kW)
* Mitsubishi Lancer 1.6 L/1.8 L MIVEC 4 cyl with INVECS-III CVT
(Asian version only)
* MG F/MG TF 1.8L
* BMW MINI One and Cooper.
* Nissan Altima (from 2007)
* Nissan Cube
* Nissan Maxima (from 2007)
* Nissan Micra 1.0 L/1.3 L
* Nissan Murano 3.5 L
* Nissan Primera 2.0 L
* Nissan Sentra (from 2007)
* Nissan Serena 2.0 L
* Nissan Skyline 350GT-8
* Nissan Tiida / Versa
* Opel Vectra 1.8 L
* Rover 25
* Rover 45
* Rover Streetwise
* Saturn ION Quad Coupe (2003-2004)
* Saturn VUE 2.2 L AWD (2002-2005), 2.2 FWD (2002-2004)
* Subaru R1
* Subaru R2
* Subaru Stella
* Toyota Highlander Hybrid 3.3 L 6 cyl
* Toyota Camry Hybrid 2.4L 4 cyl
* Toyota Prius 1.5 L 4 cyl


Dan D
'04 A4 1.8Tq 6-speed

 

Yeah, my friend's Prelude of mid -80s did same thing.

 

I would really prefer that Honda would make a Volvo 240 wagon with
performance suspension and an MT, but I have pretty much given up
hope.

See my comments below. Few of these are currently available in the
US,. If you eliminate the hybrids, I think there are only about
three. Partly this is due to most CVTs being designed for small
engines.

Most CVT designs seem to be reliable and the efficiency improvement is
significant compared to conventional ATs. I really think that the
test drive turns off a lot of buyers because it is so unconventional.
Honda is apparently selling a "7-speed CVT" - talk about an oxymoron.
This is a sure sign that buyers are turned off by normal CVT
operation. Hybrids may be the thing that brings CVTs out of the
closet.

See comments below.

The only US Civic currently offered with a CVT is the Hybrid.

I haven't heard of a Honda City in a long, long time. Are they still
sold?

Never sold in US.

Discontinued - will probably be replaced.

No CVT in US market.

I am a little skeptical of those dates. I didn't think they were on
the market that long before it was discovered that every single one of
them breaks. And GM wonders why it is going out of business. LOL

Subaru Justy (probably equals one of above models) was sold with a CVT
in the US for a few years in the 90's. Subaru hasn't sold a CVT in
the US since.

 

Not sure I understand. My GS-R never downshifts on its own.

It is just a personal preference. I like the engine to be positively
coupled to the wheels.

No, I understand that (unlike a slipping clutch) there is a benefit to
the slip designed into the AT. I just don't like the feel of it and
the benefit is more than eaten up by the inefficiencies that come with
it.

Looking at the differences between the ATs in the econo cars tested by
CR, Honda looks about as good as the other ATs (except for the CVT.)

OK, explain it to me. My understanding is that it is just a trick to
get the engine running at a slightly higher rpm to produce more power.
Kind of like a mini downshift. All car transmissions are torque
multipliers. They take high rpm/low torque and turn it into low rpm
high torque. If it were perfectly efficient, the power output would
be equal to input but of course it is always less. No way to get more
power out unless you put more power in, i.e. run the engine at higher
rpm.

The why doesn't the Versa with a CVT get better mileage or accelerate
faster than the Versa with an MT? Unfortunately, there are few cars
which allow you to directly compare CVT vs. MT.

That is what I recall. The car was called the Justy.

I think the Honda 600 would have blown its petals off. ;-)

Does the Versa do that? CR didn't mention it.

Maybe. I would gladly trade the AT in my Ody for one if it was proven
reliable. Not all are. The on in the Saturn Vue was a disaster, but
I guess you have to expect that from GM. The Japanese units don't
seem to have any problems.

 

if it doesn't, then there's something wrong. how old is it?

that's what the lockup clutch in the torque converter is for.

you'd hate cvt. there's no "relationship" between revs and engine speed
at all.

you're looking at fuel economy, right?

ok, yes, but we're talking about different things. torque converters
can increase torque output from a little to a lot in a very limited rev
range. ratio change is something different and that's what the gears
are for.

see above.

civic hx was significantly more fuel efficient than the stick.

don't know. given "consumer demand", i expect so.

i've never heard of problems with the civic hx.

 

It is a '94 with a 5-speed manual transmission. What kind of MT cars
have you driven that shift themselves???

But it isn't engaged all the time. When it disengages, that is when
it "slips" and I do not find that satisfying as a driver. Like I said
a the outside, it is a preference for MT. I like to drive cars and
the MT is more enjoyable than the ATs I have driven. I don't like it
shifting when I don't want it to and I don't like the slippy feel of
the torque converter. The fact that the MT is usually faster and more
fuel efficient is a bonus.

I think you are probably right. That is why I mentioned the fact that
the CVT isn't very popular in the US (if anywhere) and I think it is
because lots of people hate it. Why else would Honda sell a 7-speed
CVT?

OTOH, it probably appeals to - or at least doesn't repulse - the
hybrid buyer because it befits the unconventional nature of the car. I
realize there are technical benefits to the combination of hybrid and
CVT, but I am saying that the unconventional nature of the CVT is less
of a negative when you are already committed to buying an
unconventional vehicle. If you are attracted to the hybrid because it
is unconventional, the CVT is a plus.

Fuel economy was significantly better for the MTs but the biggest
difference was acceleration. The MTs blew the doors off the ATs. In
terms of 0 - 60 time differences, the Yaris AT was the best - "only"
2.1 seconds slower than the MT version. Even the slowest MT car, the
Kia Rio was faster than the Versa CVT. The fastest AT car, the Yaris,
was 1.4 seconds slower than the Versa CVT.

You understand that the ATs torque output at a certain rpm (i.e. power
transmitted) is higher when the torque multiplication is active. There
are only two way this can happen. The first is to increase the
efficiency of the transmission. I think we can dismiss that. The
other way is to increase the power input. The only way to do that is
to increase the throttle opening or increase the rpm. The throttle
opening is determined by your foot (and it wouldn't be much of a trick
for the torque multiplier to be just an extra jerk on the throttle and
it wouldn't do much good if the throttle were already wide open.)
However, rpm is largely controlled by the transmission. The
transmission allows the engine to run a little faster and therefore
produce more power which is transmitted to the wheels. This is what I
meant by a mini downshift.

I gather that was the CVT-equipped model. They don't sell it anymore.
I guess people hated it more than high fuel costs.

Like I said, they hate it just like you think I would. (Actually I
would love to try one, I do think it is a neat idea and it would be
fun for a while at least. Only after the novelty wore off could I
tell you if I like it or hate it. I actually suspect that I would
like it more than a conventional AT.)

Here is an interesting review I found. (It indicates that the Versa
CVT does not have "gears," so the fact that it was slower and less
fuel efficient than the "clunky" MT is significant.) I made one
editorial comment in brackets.

--quote--
But the CVT is the one that shines. Its proprietary design, benefiting
from Nissan's global cooperation with French carmaker Renault, is
uncanny in the way it maintains optimal engine rpm within the most
fuel-efficient torque range. It senses, for example, when the Versa is
proceeding downhill and glides effortlessly into a lower gear range to
slow the car with engine braking. [What if you don't want engine
braking? It is wasting kinetic energy = fuel. What it needs in a
powerful computer with optical sensors to look ahead, evaluate the
situation and decide whether engine braking is advantageous.]
Conversely, under pedal-to-the-floor acceleration, the CVT instantly
launches the engine to its max-torque rpm, then keeps it there
unchanged until a desired highway speed is reached.

This goes against every traditional sensation of driving, wherein gear
changes trigger a momentary drop in rpm as the higher gear ratio is
engaged. There's a lot of mechanical inefficiency in that traditional
gear-change syncopation; and Versa's CVT eliminates it. When first
experiencing the CVT's behavior, it feels wrong, sounds noisy. In
truth, however, it's mostly the lack of noticeable gear changes that's
merely thwarting a driver's subconscious expectation of rising-falling
rpms as gears change.
--end quote--

http://www.carlist.com/newcars/2007/ncr1116.html

Neither have I, but then there aren't a lot out there.

 

i misunderstood you.

originally, you said "If I want to downshift, I can do that." well, you
can on an auto. on my car, the shifter is in the same place as a stick
would be too. and the auto replicates engine braking when you need it -
just like you'd do yourself. really, it's a good system.

you'd hate cvt. as i said before, there's zero relation between engine
speed and vehicle speed - if you drive on engine revs, and it sounds
like you do, you'll be suffering total loss of feedback.

check the modern civics in that department.

because they rely on dealer feedback, and dealers are morons? cvt was
pretty popular in europe iirc. volvo sold them as well as daf, and they
did quite well.

nah, it's a pure engineering logic decision. cvt allows extremely good
engine efficiency. if you don't want that, you don't want a hybrid.

dude, compare like with like - not different car to different car if
you're trying to compare trnasmissions, i.e. yaris with cvt, yaris with
stick, etc. yaris stick to versa cvt doesn't work.

no, it depends on input/output speed differential. within certain rev
ranges, torque transmission is very high, even with a rev differential.
if it gets outside of that band, it drops right off.

that's the lockup clutch releasing.

my money's on dealer prejudice, not consumer. by the same token, the
hatchback has been all but dropped in the u.s. afaikt, that's more to
do with vehicles with the same utility selling for $30k rather than $15k
for a hatch, not consumer demand. try buying a used hatchback civic
here in the bay area - good luck! people just keep them - they never
sell.

not correct. when engine braking, fuel delivery is completely stopped.

why? i don't want my car making /that/ kind of decision. seriously,
auto engine braking only happens when you're foot braking - just like on
a stick. you can't criticize what you've not used dude.

/all/ the 96-2000 hx autos are cvt.

 

The AT Civic gets slightly better highway mileage than the MT - I am
guessing it may have a higher final ratio. The Accord 4 and V6 and
the Fit all get better mileage with the MT. I don't have any test
results, but I bet the MTs are universally faster (see below.)

Why is that in the past tense? We agree they are more efficient than
conventional ATs and if they were popular, why didn't they drive
conventional ATs off the market? Reliability could have been an issue
but shouldn't be now (as long as you stay away form GM.)

Exactly right. The converse of that statement is that, if you want
increased efficiency, you will tolerate or even embrace the CVT. And
if you like the hybrid because it is odd or technologically advanced,
then you will love the CVT.

It doesn't matter whether you compare like to like or unlike to like.
All of the MTs are faster than all of the ATs and the CVT. Let me
tabulate it for you:

0-60 45-65 1/4 mi

Fit AT 12.4 8.4 19.0
Fit MT 9.9 6.5 17.4

Versa CVT 10.1 6.4 17.8
Versa MT 9.5 5.9 17.2

Rio AT 12.8 8.1 19.3
Rio MT 10.0 7.1 17.5

Accent AT 12.5 7.7 19.1
Accent MT 9.5 6.5 17.2

Yaris AT 11.4 6.9 18.6
Yaris MT 9.3 6.0 17.3

As I said, "The MTs blew the doors off the ATs."

http://en.wikipedia.org/wiki/Torque_converter#Efficiency_and_Torque_Multiplication

--quotes-- [my comments in brackets]

Unlike a fluid coupling, however, a torque converter is able to
multiply torque when there is a substantial difference between input
and output rotational speed, thus providing the equivalent of a
reduction gear. [IOW, a mini-downshift, a slightly lower gear that
allows the engine to run faster and produce more power.]

The principal difference is that whereas a fluid coupling is a two
element drive that is incapable of multiplying torque [IOW, it has a
1:1 ratio of input to output] , a torque converter has at least one
extra element - the stator - which alters the drive's characteristics
during periods of high slippage, producing an increase in output
torque. [IOW, it allows the engine to run faster and produce more
power, just like a lower gear.]

The Buick Dynaflow automatic transmission was a non-shifting design
and, under normal conditions, relied solely upon the converter to
multiply torque. [IOW, there was no gear transmission, all ratio
change was due to slippage of the TC - an early CVT!] The Dynaflow
used a five element converter to produce the wide range of torque
multiplication [i.e. wide range of drive ratios] needed to propel a
heavy vehicle.

* Acceleration. The load is accelerating but there still is a
relatively large difference between pump and turbine speed. [i.e. low
gear] ...The amount of multiplication will depend upon the actual
difference between pump and turbine speed, [i.e. the effective drive
ratio] as well as various other design factors. [efficiency]

* Coupling. The turbine has reached approximately 90 percent of
the speed of the pump. Torque multiplication has ceased [i.e. gear
ratio is slightly less than 1:1 but the slight power increase from
higher engine rpm is lost to inefficiency] and the torque converter is
behaving in a manner similar to a fluid coupling. In modern automotive
applications, it is usually at this stage of operation where the
lock-up clutch is applied, a procedure that tends to improve fuel
efficiency.

--end quotes--

When they say "torque multiplication" what they really mean is a drive
ratio less than 1:1. IOW, every transmission is a torque multiplier,
at least in the lower gears.

Right, there is no torque multiplication in the TC unless it is
slipping.

I personally like hatchbacks and I know they have a following. I too
am surprised and disappointed that they have all but disappeared. I
don't know I am ready to sign on to the conspiracy theory though. If
there were a strong market, Someone like Mazda or Nissan would jump to
serve it to increase their sales. apparently there isn't enough
demand to justify the high expense of two body styles and the sedan is
more popular.

I suppose I could blame the shortage of MTs on greedy dealers and
manufacturers who want to force me to buy a more expensive AT.
However, I am more inclined to blame Starbucks.

But kinetic energy is being lost. Doesn't matter if the car has to be
brought to a stop anyway, but if the driving situation requires little
or no compression braking and the computer orders a lot, the car will
slow unnecessarily and fuel will be consumed bringing it back up to
speed.

I use compression braking a lot. Sometimes I use a little, sometimes
I use a lot. Sometimes I coast with the clutch disengaged for maximum
distance. A transmission that always applies medium compression
braking is not as going to achieve the same thing.

But you are satisfied with it making the decision mindlessly. I agree
I do not want the car making that decision. I want to make it myself
and shift the transmission accordingly. My brain is the powerful
computer and my eyes are the optical sensors.

Not true. I use compression braking all the time with my foot off the
brake. Descending grades would be a prime example except that I live
in Chicago and there are no hills. Instead, I am the only guy in
crawling rush hour traffic not flashing his brake lights every 20
feet. It is way more fun than an AT if you play the game.

I am only pointing out that this feature has a down side. It might
not bother 95% of drivers, but it would bother me.

Yes, but how many is that? If they had sold that many, it would still
be on the market. Don't get me wrong, I don't think they are any less
reliable than a conventional Civic AT, but I don't think there are
enough out there to really know for sure. They certainly aren't
terrible like the GM CVT.

 

Gordon McGrew wrote:

that's unsafe btw.

no i'm not. i am satisfied from extensive experience over many years in
all conditions and many many miles, clearly based on extensive research
on driver usage and testing of driveability, that programmed engine
braking algorithms used in electronically controlled automatics are
highly proficient and effective. as you would know if you'd driven one.

i don't want it making an independent decision. they're programed to
make *dependent* decisions based on how the driver is asking the vehicle
to behave. which is what you want.

you can - use the shift lever.

but the two are apparently unable to work together to get the ass on
into a dealer to test out the new fangled machine the mouth is criticizing.

no, it's true. autos engine brake, just like a stick. and you can
engine brake without the foot brake too. we've discussed that repeatedly.

see above.

but your assessment of the whole situation is flawed - it's assumption
and speculation /not/ based on either experience or sufficient
knowledge. modern autos shift to engine brake. they do it flawlessly
and just as a normal driver would shift a stick. and the degree of
braking depends on how hard the driver's braking - /that/ is /more/
sophisticated than the average stick driver.

 

It can have all the algorithms it wants but it doesn't know whether
the hill is long or short. It doesn't know whether, at the bottom of
the hill, there will be the beginning of a steep ascent or a freight
train crossing. It just goes for some predetermined drive ratio,
oblivious to what is outside the window. I chose the level of
compression braking based on information the computer just doesn't
have.

No, I want to tell it what to do. I don't want it to infer what I
might want the transmission to do based on what I am doing with the
throttle and brake. At least a conventional AT gives you some direct
control over this. I would like to believe that the CVT does also,
but I don't really know. It should assume that I want minimal
compression braking unless I specifically signal otherwise. If it
wants to assume I want more compression braking if I am at least
moderately on the service brake, that is OK. But if I take my foot
off the brake, it should resume minimum compression.

Not clear on how you control the CVT, but the article implied that it
automatically went to some medium level of compression braking. It
wasn't clear that you could over-ride this and force less or more
compression braking.

That's just it. I don't test drive cars unless I am considering
buying one. If I get the opportunity, I would gladly take it. But I
don't think I would ever consider buying one if an MT were an option.

But you said it happens *only* when you are foot braking. I thought
you were referring to the CVT. I know how a conventional AT works.

It may or may not be more sophisticated than the *average* stick
driver but it is no way more sophisticated than what *I* do. I can't
decide what gear to be in without assessing the situation outside the
windshield. No matter how powerful the computer and elegant the
software, it is a blind driver. I use engine braking instead of the
service brake. To have it mindlessly aping what I do with the service
brake is hardly sophisticated.

 

It doesn't allow engine braking for one thing and it's illegal for
another.

 

FWIW, neither of those responses have anything to do with safety,
although I suppose you could make a tenuous case for the first, given
some not-obvious assumptions about manufacturer's intent to provide and
buyer's intent to use engine braking.


RFT!!!
Dave Kelsen

 

For one thing, the fact that coasting doesn't allow for engine braking
is a safety issue. For the second, the fact that it is illegal makes it a
valid point.

 

Gordon McGrew wrote:
<snip>
you just want to express your opinion, not discuss merits of either
system. that's fine if the opinion is informed, but since you have no
experience and apparently don't wish to pay any attention to fact, then
your opinion isn't opinion, it's mere prejudice.

i'm sorry i wasted my time.

 

Saying that coasting is unsafe because it doesn't allow engine braking
is like saying that not pushing on the brake pedal is unsafe because
it doesn't allow frictional braking. Engine braking is available if I
want it, just like frictional braking. When and where each is used is
a decision to be made by the driver based on the situation. For
example, coasting on glare ice is a lot safer than compression
braking, especially on a rear wheel drive car. Even more so with the
advent of ABS.

As for laws against coasting; they may vary from state to state. Here
is one form Maine:

An operator, when traveling on a downgrade, may not coast with the
gears of the vehicle in neutral. [1993, c. 683, Pt. A, §2 (new); Pt.
B, §5 (aff).]

Now notice that it specifies coasting *on a downgrade* *in neutral*.
Coasting on level ground or coasting down a hill with the clutch
disengaged but the transmission in gear is legal. I would agree that
this is generally a bad idea and certainly bad if you are riding the
foot brake. However, if you are coasting down the hill with the
clutch in, not using the foot brake, and you are satisfied that your
speed is not excessive, what is the problem?

The only purpose of such a law is to give them another charge to throw
as some idiot who causes a wreck because he doesn't know how to
control his vehicle. Can you imagine being pulled over because you
were coasting down a hill?

And just to be sure we are perfectly clear on this point, I use more
compression braking and less frictional braking than about 95% of
drivers in the same situation. But I don't use any braking where it
is not needed.

 

I stand by my original position; if it doesn't know what is happening
on the road ahead, it cannot possibly make the best decision regarding
operation of the transmission.