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Similar problem?
I'm wondering if my car has the same issue ('07 335i, 82K, had the mechatronic sleeve fixed under warranty several years ago due to a leak). It's always shifted smoothly and I've never had problems with jerky downshifts when coming to a stop. Here's what happens:
1) Get the car on the open road (think LA to Vegas) and drive it 75+ for a good hour or so, this ensures the transmission is at high temperature.
2) When going ~65 or so, push the gas pedal down about halfway which will trigger a 6->4 downshift.
3) BANG! The whole car jolts and you check the rearview mirror to make sure there isn't a pile of broken gears behind you.
Alternatively, from a constant 60+ mph you can trigger a manual downshift with the steering wheel paddles and you'll get a similar jolt, just not as bad because you don't have a lot of engine power behind it.
It's done this for a while but it seems to be getting worse. It will NOT exhibit this problem unless the transmission is at high temperature. If I drive it for 20 minutes at the typical 65-75 speeds around here, it behaves normally. Has to be like ~80mph for a long time to get it hot first.
Time for a fluid change? Maybe this solenoid thing is to blame? Does old transmission fluid's viscosity change significantly when it heats up?
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