ZF über die 9-Gang Probleme in USA

Complaints about the Cherokee—either before or after an early reflash of the transmission control software—have ranged from harsh shifts to odd shift points for this transmission as it’s installed in the Jeep Cherokee, which was one of the first models to launch with it.

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Frieder Mohr, an application engineer who’s worked with software and the internal controls for the nine-speed, said that the transmission goes through two levels of ‘adaptation’ to fine-tune its shift quality. One of those is as the transmission properly adjusts its shifts to internal tolerances, both when it’s new and as it wears. The second is adaptation to driving style, which takes just a few minutes and a few shifts through each gear.

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Tips that the dealership probably won’t tell you
Mohr gave the following useful tips on how the nine-speed’s software works:

• 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.

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