9 Speed Automatic Transmission

Photo credit: Bigstock
Photo credit: Bigstock

Will the higher number of gears bring us advancements? Not by itself, however, transmissions with higher number of gears allow us to drive at low RPM at all speeds. For example, Mercedes E350 going 130km/h in 9th gear is at 1350 RPM which saves fuel and makes the ride quieter and more comfortable.

Evoque going over rough terrain at 7 km/h is only at 1000 RPM. 9th speed is so long that Evoque would be going 330 km/h at 4500 RPM if engine had enough power. Their final goal was to lower the RPM at freeway, and they managed it making the 130 km/h ride smooth and comfortable at only 1800 RPM. However, there are still some drawbacks. When going 100 km/h transmission shifts up and down for no reason, and the downhill drive could also use some polishing.

When it comes to Mercedes, with enough power it would go up to 375 km/h, but their main goal was the comfort.

Only drawback in their case is the responsiveness. 9G-tronic sets the high standards regarding the driving characteristics and quality overall.

When going downhill it shifts down always at the right time and it brakes by itself keeping the wanted speed.

Sport dynamic wasn’t really high on their priority list in E class, and it shows. However, as we can see in the BMW example, that’s only matter of software and transmission configuration, so sporty E class is achievable with some calibration.

BMW made amazing combination with ZF 8 speed transmission and software. When it comes to performance it is still unsurpassed. Engine and transmission are synchronized to perfection, shifting is instant and with no jolting and efficiency is on top level.

ZF9HP: Front Wheel Drive

ZF’s 9 speed automatic transmission uses dynamic converter of torque. It also has vibration silencer which allows quick gear changes without any loss of comfort. Maximum torque this transmission can take is 480 Nm. Since it’s transversely mounted, gears are not in the line but rather built in each other.

It also has two clutches making it easy to mount and highly efficient. Theoretically this transmission could push a car up to a 327 km/h- at 130 km/h engine rotates 1800 a minute. Start stop function is supported without a need for additional electric oil pump. Switch which is fairly quick is used to start a car and that is more than enough.

Transmissions with more gears will certainly help us lower fuel consumption and make the ride smoother and more comfortable, but there is another side to this story. These transmissions are lot more complicated and we still don’t know how they will cope with time.