German Car Zone

Why is 7 speed auto transmission only possible with 6 and up cylinder engines ?

is that technical impossible replaced to 5 speed in 4 cylinder ? in the future it could be placed in 4 cylinder engines like C180-C200-C200 CDI and c220 CDI- ?


Thanks

I don't know, but the only explanation for me is the cost.

The old (but constantly updated) 5-speed tranny is much less expensive to produce, to manufacture... It allow the 4 cylinder cars to have a more interesting price.

Well, maybe not, it is an option for the 4-cylinder, just as expensive as the 7 I think...

Maybe is it too much to have 7-speeds with a less powerful motor: to keep good performances the gears are not too long, so with 7 speeds the gearbox would constantly changing gears because too small ratios. Whereas with a more powerful motor, gears are more long so it makes much more sense, and keep the motor at low rpm.

But honestly, the 5-speeds is an excellent gearbox, really.

The 7 speed wasn't installed with the old 6 cylinder engines, so it might have something to do with the power ratings

Yes I know, I use it

But wonder How better 7 over 5

Well ultimately the aim of an automatic gearbox is that you don't notice when it changes the gear...
I don't think you will see a great difference between the two!

The only point is the electronic gestion, maybe a bit more intelligent and responsive, the gearchange a bit quicker and a bit softer, but IMHO nothing really groundbreaking!

there is no real technical reason not to do it
they can do it
but the real question is a question of end price and product cost versus efficiency gain from 5 to 7 if any on such a small engine with low torque and hp

Yes as I think it is a problem of gear rations, if you ahve not enough power, the gears will be too long (performances very poor then) or too short (will change gears much too often), so 5 speeds are enough and 7 speeds would be an overkill.

I don't see it as a problem, 5 or 7 speeds, these are among the best automatic gearboxes in the world and both are very very good.

The S, CL, SL 600 also has the 5 speed and not the 7! You have the same automatic gearbox as the Mercedes' flagships, should be happy!!!!

Thanks guys for good info. Understand

Hello,

I'm writing from Turkey. A Mercedes Benz dealer said to me that 7g tronic will be available for 4 cylinder engines so far. I have planned to buy a c 220 cdi with 5 speed but now I will be waiting. Is it possible do you know anything about this situation ? According to this sittuation I will order or wait new w204 c220 cdi.

Regards

Yiğit

Which old V6 are you referring to?