why so many multi speed automatics?

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why just recently do you see more 5, 6, 7 ? speed automatics? Has there been some break thru in auto trans design in the last 5 years that did not exist in decades past?
 
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I would guess that it's part of the quest for more MPG.
 
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JTK

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I'm sure having manufacturing process that makes them cost effective plays a role, but increasing fuel economy is the main reason.
 
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Originally Posted By: edwardh1
wonder what that adds to weight cost and complexity/reliability of the trans?
Yes it does. GM and Ford developed their 6 speed automatic together and there was a major problem In one part breaking. I agree the major reason for these is improving mileage.
 
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More gears also means better suiting the engine output for the demand, which makes the driving experience more pleasant. Mostly gone are the days where a transmission would make the engine scream to climb a tiny hill just because the top gear was a hair too tall. I've had a few cars like that. More gears also means that a turbocharged engine stays in its powerband better. No point in redlining the engine when bumping up a few hundred RPM will spool up the turbo to provide the power without a lot of unpleasant engine noise. Basically, they make modern small turbo engines perform like larger engines of yesteryear. More gears does not automatically mean more weight or more parts. IIRC it was ZF that said their 8-speed auto reduced parts count and weight over their previous 6-speed auto. Fewer parts to break and less weight with a better driving experience is a good thing, at least to me!
 
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Originally Posted By: joegreen
i think dodge is up to 9 speeds in some of its vehicles.
That's right. 8 and 9 speed autos are now becoming common.
 
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I don't like this development very much. Added complexity with electric oil pumps etc. will kill reliability and increase repair costs. Manufacturers should just develop regenerative braking systems and cvt:s for efficiency. I don't understand why anyone hasn't developed direct drive combined starter/alternator/booster/regen motor for ordinary IC engine to replace separate alternators and starters.
 
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Originally Posted By: Olas
It's because people are too [censored] lazy to change gear.
LOL laugh I wish my manual had a 6th overdrive...
 
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Originally Posted By: Nebroch
I don't like this development very much. Added complexity with electric oil pumps etc. will kill reliability and increase repair costs. Manufacturers should just develop regenerative braking systems and cvt:s for efficiency. I don't understand why anyone hasn't developed direct drive combined starter/alternator/booster/regen motor for ordinary IC engine to replace separate alternators and starters.
It's not as if they wouldn't, but I think such a device might need some "unobtanium" to make it work effectively at each task. The full-hybrid drive trains do use a motor/generator in the driveline, but controlling it and switching the current to do those two tasks adds an expensive computer, switchgear, and wiring harness to the car.
 
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Originally Posted By: Nebroch
I don't like this development very much. Added complexity with electric oil pumps etc. will kill reliability and increase repair costs. Manufacturers should just develop regenerative braking systems and cvt:s for efficiency. I don't understand why anyone hasn't developed direct drive combined starter/alternator/booster/regen motor for ordinary IC engine to replace separate alternators and starters.
I don't get it either. On board generation of electricity to drive the wheels seems to be more sustainable from an ownership perspective http://www.roadandtrack.com/go/out-of-turn-toyota-engine
 
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I'm skeptical too..... Especially with known bad TCM programming logic we're seeing more and more these days. My Dad's 300, the first weekend he got it, Went ~550 miles to Columbus, OH. Doing *cough* the speed limit, air on, stopping from time to time .....Got 31.5MPG. Did it in less then 1 tank. For a man who's been driving beat up B bodies and Panther platform vehicles for the past two decades, he was shocked as well. ..In a nearly two ton vehicle ...With a large-ish V6 ....Not driven in a intentionally economical fashion .....Not in a 3 cylinder Fiesta SFE ......In a LARGE AMERICAN RWD car Why.... Because 8th gear. After 1yr/40k of Livery use, its lifetime fluid fill seems to be holding up just fine
 
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Lifetime fluid is other funny invention. Usually that "lifetime" appears to bee rather short period for the owner.
 
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It's because they haven't figured out how to make a good, reliable CVT for anything but the smallest, lightest cars (and even that is questionable). So a normal automatic with more gears is a compromise to more closely approximate a CVT for a larger car (and I am using the word "larger" loosely).
 
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Originally Posted By: 2cool
It's not as if they wouldn't, but I think such a device might need some "unobtanium" to make it work effectively at each task. The full-hybrid drive trains do use a motor/generator in the driveline, but controlling it and switching the current to do those two tasks adds an expensive computer, switchgear, and wiring harness to the car.
Might be cheaper than to develop and make new tranny. Electric motors and especially inverters have developed so much in last few years. As an european consumer I can buy 5.8 kW 3 phase grid-tie solar inverter (ABB Power One Aurora) for 1200 eur including VAT. What would 12 V -> 300-400 AC inverter and 5 kW direct drive motor cost for a car manufacturer, maybe 700 usd? Of course that's more than normal alternator + starter, but it would be much simpler (and durable!), more efficient and could regen too.
 
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Originally Posted By: zzyzzx
It's because they haven't figured out how to make a good, reliable CVT for anything but the smallest, lightest cars (and even that is questionable). So a normal automatic with more gears is a compromise to more closely approximate a CVT for a larger car (and I am using the word "larger" loosely).
You got that right. By Chrysler getting pretty much all of their transmissions from ZF instead of using CVTs, they won't have the worst transmissions in the business. I'm glad they went that route instead of the CVT. Instead, that position will now be reserved for Nissan and companies that use Nissan CVTs.
 
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