Problems with 4WD system

Hello,

I have some problems with my WK2 2011 Jeep Grand Cherokee Laredo, 3.6, 4WD, 60k kms, which my garage seems not to be able to solve. I searched the forums, but couldn't find a similar problem.

I purchased the car new, moved to Romania and since half a year am experiencing the following:

• Shock at acceleration. Most present in lower gears. 
Not always there at cold start, but after a few minutes it is always there.
In low gearing: no shock at all. Smooth gear changes.
• At 95 to 100 km/h and at 120-125 km/h: bonking and some shaking. It seems that the four wheel drive system seems to change power distribution to the wheels. It seems independent of the gear you are in and the rpm.
  • If it succeeds: bonking stops and car drives perfectly;
  • If not: you hear a high pitch sound (whining) as if wind is blowing through something from the 4WD system and during acceleration you will hear zzzz.…zzzz….zzzz….zzzz. 
Sometimes bonking continues as well, sometimes it stops until you come again at 95 to 100 km/h and at 120-125 km/h. Especially when you drive uphill, then the bonking continues.
• I once put the car in Neutral when this happened and let the car coast. When putting it in drive again, the gas didn’t react and the car just drove 80 km/h. After stopping, the car behaved normal again.
• If you select a 4WD mode in the car, it doesn’t really make a difference, however in Sand/Mud there seems to be a continuous vibration.
• There is now a strange sound in low gearing, around third gear.

What has been done so far:

• Replacement of front cardan axle: this solved the shock at acceleration for a while.
  Car got service check and winter tires were changed to summer tires: shock reappeared.
• All drive axles were changed: no improvement;
• Rear cardan axle was replaced: no improvement, apart from the fact that now the rubber disk (Hartman disk) had to replaced;
• Some rubbers were replaced: no improvement.

Does this sound familiar to any of you? And how did you solve it?

Thanks in advance,
Jasper

Problems with 4WD system