THUMP when shifted into reverse

[Gablesdad]

This just happened while backing out of a parking spot. I had my foot on the brake, shifted from PARK to REVERSE and a loud THUMP was felt as it engaged. All worked normal when shifting down to DRIVE. I put it in PARK again, foot on brake shifted into REVERSE (to see if i could duplicate issue) no thump.

Any ideas ??

 

[chefduane]

Driveshaft U-Joints perhaps? Same thing happened to me and it turned out to be the front U-J that torqued a little when put into gear. Got progressively worse. I ended up replacing both F + R and now all is well. Was less that $50 for both - although I have a '98 4x. Don't know costs for an '11.
Put the start the car with foot on the brake and then shift from fwd to rev a few times. If you get a 'clonk' each time you shift, it's quite possibly the driveshaft u-joints.

 

[1995E]

Well, it might have been a transmission bump issue. Those were common in the 2011 and 2012 Explorers.