7 speed vs 8

[t walgamuth]

is the seven speed automatic generally thought to be inferior to the eight speed?

[tbomachines]

This will not answer your question, but IIRC that 8 speed is a DCT and not the venerable ZF 8 speed which is an absolutely epic transmission. Too bad.

The 722.9 in my e550 is pretty dismal. I have to imagine they were quite different in the AMG models because its quite literally the worst part of the car -- I have heard it is down to a lot of the tuning, so slow from a stop that it causes panic in situations where you really need to go. A TCU tune will do wonders I think....

[t walgamuth]

So the ZF is the way to go.

Thanks.

[tbomachines]

Originally Posted by t walgamuth

So the ZF is the way to go.

Thanks.

Are you talking about mercs or in general? I am not aware of any MB that uses the ZF 8.

[Frank Reiner]

Originally Posted by t walgamuth

Is a seven speed automatic generally thought to be inferior to an eight speed?

The appropriate division of any gear ratio spread is a function - in its simplest form - of vehicle weight, available power, and required operating speed range of the vehicle.

A light vehicle with relatively high power may operate satisfactorily with 2 speeds.
A highway tractor pulling doubles @ 60,000lbs will often have 16 speeds.

As Lloyd Price put it in "Stagger Lee" - "poor man, he threw eight!"
If Billy had thrown seven he might have lived.

[t walgamuth]

Originally Posted by tbomachines

This will not answer your question, but IIRC that 8 speed is a DCT and not the venerable ZF 8 speed which is an absolutely epic transmission. Too bad.

The 722.9 in my e550 is pretty dismal. I have to imagine they were quite different in the AMG models because its quite literally the worst part of the car -- I have heard it is down to a lot of the tuning, so slow from a stop that it causes panic in situations where you really need to go. A TCU tune will do wonders I think....

what is a DCT please?

Thanks for responding.

[t walgamuth]

Originally Posted by tbomachines

Are you talking about mercs or in general? I am not aware of any MB that uses the ZF 8.

yeah, I am talking about mb. I also was thinking the trannies would be found in other german vehicles.

[t walgamuth]

Originally Posted by Frank Reiner

The appropriate division of any gear ratio spread is a function - in its simplest form - of vehicle weight, available power, and required operating speed range of the vehicle.

A light vehicle with relatively high power may operate satisfactorily with 2 speeds.
A highway tractor pulling doubles @ 60,000lbs will often have 16 speeds.

As Lloyd Price put it in "Stagger Lee" - "poor man, he threw eight!"
If Billy had thrown seven he might have lived.

Thanks for responding, Frank. I was hoping for some more focused information. I guess my question was not focused enough.

[tbomachines]

Originally Posted by t walgamuth

yeah, I am talking about mb. I also was thinking the trannies would be found in other german vehicles.

So Merc doesnt do a whole lot with 8 speeds -- did a quick google search to confirm, but they have 7 and 9 speeds, go figure. The 8 speed is DCT (dual clutch) and is in some of their 4cyl applications. The CLA stuck out in my mind, I think that is one of them. FWIW I believe Mercedes makes all their own transmissions. the 7G and 9G are in-house.

No Merc got the ZF 8 speed which is a very robust traditional auto box. BMWs almost all use that transmission, as do a lot of Audis (and porsches, maseratis, dodge ram/chargers, Jag/LRs etc etc.). Our grand cherokee has it, and I swear it is damn near telepathic. The ZF8 is regarded as one of the best boxes of all time, and for good reason. They hold a lot of torque in most applications, shift quickly, and have very little driveline drag, making them pretty efficient.

[t walgamuth]

I thought most of the newer cars suvs had the dual clutch trannies now. The wife's 320a is a 4 cylinder with turbo gas motor...seems to have the 9 speed.

My touareg seems to have an 8 speed.

[oldsinner111]

vw's early dual clutch auto's junk. people for get NASCAR uses still 4 speed over 200 mph.I guess 10 speeds for new weak aluminum bangers.