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My car is a BMW 5 series with the ZF8 automatic transmission. It doesn't shift perfectly - jerks a bit in all gears shifted in the first drive of the day, for around 10 miles then it becomes much smoother. 1-2 gearshifts are sometimes noticeable, especially if the acceleration is very slow - or every time at any acceleration in the first 10 miles.

Also, there is a jerk similar to a jerk happening during a gearshift (like a hard engagement of a clutch) which happens in 1st gear without shifting in 2nd! It happens for example if I accelerate slightly from a dead stop in manual mode gear 1 and can be felt around 1200 rpm. Is this the torque converter clutch, engaging in gear 1 at 1200rpm? (car is diesel).

Also, when braking and almost coming to a stop there are two moments when a jerk can be felt (like a bump that is affecting my linear braking). Maybe it is shifting gears 2-1 and 1 disengaging?. When the car has just stopped very rarely a small jerk appears - car is trying to lurch forward for half a second.

Can all these jerks (1-2 gearshift is always most pronounced compared to the others) be caused by a failing torque converter?

There are no errors and the transmission has been serviced. There are no other symptoms.

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Could be the torque converter. Here's a basic test:

Sitting in the driver’s seat, start the engine. Let the auto warm up for 4-5 minutes. Then step on the gas pedal gently, revving the engine twice. When it comes back to idle, step firmly on the brake, then shift the transmission into drive. You’re looking for whirring, clicking, or lurching when you do so, which are all problem signs of a failing torque conveter.

Slowly move the transmission through all gears, including reverse. Again, listen for clacking or whirring. Note if any of the gears fail or if the vehicle lurches.

  • There are no sounds. The lurching happens in the moment I've just stopped completely and holding the brake. I am not very sure if a failing converter can affect gear shifts and I'm also curious what is the noticeable engage (a minor slam from behind) around 1200 rpm in 1st gear. After servicing the transmission there is only one minor jerk like this but before it was more like a pulse - several small jerks around 1200 rpm in 1st gear and very light acceleration. Since I am not shifting to 2nd I am thinking the torque converter clutch must be engaging, but in 1st gear? – CristianC Aug 23 '18 at 17:30

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