Transmission shifting hard

2012 MERCEDES BENZ E350
160,000 MILES • 3.2L • 6 CYL • TURBO • 2WD • AUTOMATIC
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DA3OOR
  • MEMBER
  • 1 POST
While driving on the highway (90kmh) if I floor the gas pedal for a few seconds (now around 120kmh) and then lift it off immediately, the next gear comes on so aggressively and I hear a loud bang from the back of the car, it feels almost like someone rear bumped into me. I think it happens only between 5th and 6th gear
If I do the same thing but with slightly pressing the gas pedal nothing would happen and the gear would change nicely.
Feb 23, 2022 at 10:32 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,248 POSTS
Hi,

Since it doesn't do this under normal conditions, it doesn't sound like a transmission issue, but rather a worn flex joint on the driveshaft.

When you are full throttle and then let off, pressure is released and there is a drag on the driveshaft in the opposite direction (engine slowing vehicle). If there is play and you hit the throttle again, you can get a clunk if there is excessive wear.

If you look below, pics 1 and 2 explain how to inspect the parts. Pics 3 and 4 explain how to replace the fitting sleeves on the flex disc. I have a feeling if you inspect them, they are the cause of the issue.

Let me know if this helps or if you have other questions.

Take care,

Joe

See pics below.
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Feb 24, 2022 at 11:08 AM
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