Nine is the new six, but the arrival and adoption of nine-speed automatic transmissions hasn't gone as smooth as hoped.
Driveability has been the prime concern, odd shift points and harsh shifts have manifested on both the Cherokee and the Renegade early in their lifecycles. However at a recent ZF tech day The Car Connection found that the fault may not lie entirely with the hardware per se, but a combination of components and calibration.
Comparing the same nine-speed in the Discovery Sport to the two Jeeps back to back they found that "the unit's somewhat softer, more conservative calibration works to the benefit of drivability and smoothness in the Discovery Sport, versus those Jeep models."
ZF CEO Stefan Sommer believes that part of the issue may lie in the fact that Americans drive different. “We need to focus more on the regional-specific perception of how such a complex machine like an automatic transmission is working in the car, and as a consequence we have made a decision to bring more application engineering into the U.S....to be closer to the U.S. customer, to even frontload, in this tuning application work.”
Frieder Mohr, a ZF application engineers offers tips to consumers that the dealer probably can't. The nine-speed is a smart gearbox, it learns as you drive and that may be where certain issues are manifesting.
- If you’re the gentler driver in the household, a few lumpy shifts are to be expected each time you get in after the more aggressive one. If one driver drives rapidly most or all the time, then it’s possible that the low-speed, low-load shifts won’t work so well, because the transmission will still be assuming the style of the more aggressive driver. It is possible that each time the gentler driver gets into the vehicle, the first few shifts may be firmer, but the software softens shift quality after just a few minutes of driving.
- It’s actually important to mix driving styles when the vehicle is new. This is so that the transmission can ‘learn’ each shift over a range of conditions. The transmission could take longer to adapt if driven in a steady continuous way, but shifts should even then become smoother and more predictable over the long run.