? for those who drove new smart semi-auto tranny

[kmeinhold]

I'd like to see if there are faster 0 - 60 runs using the paddle shifters. Could we shave one perhaps two seconds off of the 14 seconds?

PS: Still faster than a Hummer H-1 (0 - 60).

PS2: OMG I just got pulled into discussing 0 - 60 on a smart car... this is not a performance car.

[mr_Cash]

second question:

is it possible, that the long one second shift delay, is due to the computer control of the gear engagement, to ensure a long lifed clutch,

versus the standard manual, where frequent speed popping the clutch, would significantly shorten the life of the clutch and transmission?

ie, popping the clutch with a standard manual may be a faster shift, but, while doing so, the high friction of speed shifting grinds the clutch down.

and the long one second shift, may better, more smoothly engage the gear from one to the next, giving minimum friction, and maximizing the life of the clutch, and hence transmission?

this is a question. not a statement. i have no idea if this has relevance to transmission and/or clutch life.

if the semi automatic smart design did help extend its clutch/tranny life, that would be nice to know,

and would make living with the slow shifting, much more pleasing, knowing its protecting the car.

any engine/transmission pros here, have any thoughts on this possibility?

thx.

[saronian]

It's my understanding that small size, limited weight and low cost are the design factors which created the transmission. Although I read plenty of bad things about the slow nature of the shifts, I was presently surprised when I test drove the fortwo back in May. I foresee my driving style quickly adapting to match the fortwo's limitations, and accept them in exchange for using a micro car in my commute.

[mdfortwoguy]

I have driven a 450cdi, a Euro 451, and a US 451.

I found the shifts of the US 451 to be comparable to the Euro model I drove. I did not have as much time in the euro though, so that perception might be a bit skewed. It seemed better timed, however (due to the lower 1st gear I suppose).

I shift my current vehicle at about the same rate as the smart shifts during normal driving. The 2.2L in the VUE is very slow to drop revs due to a heavy flywheel and emissions tuning, and I tend to let it match between shifts to save wear on the clutch. That being said, when I have my foot on the floor, the transmission in it is wonderful enough that I can go through the gears as fast as I possibly can - and the syncros and everything else keep up.

The smart is a big step for me... I am a horrid leadfoot. The NA spec 451 I drove was playful, but in automatic mode, it didn't feel like it wanted to be rushed. That's okay for me though - this is the first car that I have driven that is fun without being terribly fast.

Not to segway, but the NA spec 451 seemed to be smoother at idle and under acceleration, and as it was told to me - it has more sound insulation. It seemed to be significantly quieter than the euro 451 all around. The 3 cylinder still makes a wonderful growl at high revs though.

[jonnysan]

Originally Posted by lhoboy

The shift time on this tranny is a full second. The acceleration curve is the choppiest I have seen on any car (see below). The typical "driving enthusiast" takes far less than a second to complete a manual transmission shift.

paying that much attention to those kinds of particulars. As you have said, most likely their will be ways to really *americanize* the shifting program once backyarders like us get their hands on the car....;) All after the warranty is off....that is.

[jonnysan]

Md and Saronian have both said it better than I could....

I'll get used to it and still enjoy driving it all over the place!

[a2jack]

I have not driven the USA-451. I did drive two Euro 451s and my wife drove another. Our conclusion was negitive with regard to the trans. The rest of the car was wonderfull.

I have witheld comments on this subject in hopes the USA 451 would be fixed.
However, from the reports, it is not.

The problem is NOT shift time, but the sudden loss of foreward momentum while merging at full power.

Yes, one will learn how to handle this little quirk, we will, and expect our car in Jan. But older drivers or younger ones who never really learned to drive with skill. will get in trouble, quick.

I foresee problems ahead.

A2jack.

[spdickey]

Originally Posted by a2jack

I have witheld comments on this subject in hopes the USA 451 would be fixed.
However, from the reports, it is not.

The problem is NOT shift time, but the sudden loss of foreward momentum while merging at full power.

Yes, one will learn how to handle this little quirk, we will, and expect our car in Jan. But older drivers or younger ones who never really learned to drive with skill. will get in trouble, quick.

Can't fix a "problem" that is inherent in the transmission. All transmissions with a clutch vs. a torque converter will lose momentum when the clutch is disengaged, whether the clutch is operated manually or automatically as is the smart's.

However, I have driven both Euro 450s (Italy and USA) and also Euro and USA spec 451s. The transmissions are much smoother now than before, but its still a clutch based system. Let's be glad this has been revealed and discussed to death. Either you like it or don't, but Mercedes decided it was the best solution for a low cost, fuel efficient drive train for the smart.

[jwight]

Not too worried about the transmission shift behavior, but that 19.2 sec 0-70 time is going to make merging onto the Interstate really exciting.

[OC1Dave]

I don't see what the problem is - I always merge onto busy highways in my stick shift cars by flooring it in first, let up on the accelerator, select the next gear, WAIT ONE FULL SECOND, refloor the accelerator, etc. This technique only slows my 0-100 time by THREE SECONDS! Maybe thats why the guys at the drag strip are always laughing at me?;)