Hi Scott, my wife drives a 2009 Hyundai tucson 2.7 v6 4wd. She complains of a rapid thud sound coming from somewhere in the front of car under floor. It occurs when she lifts off the gas at say 20 to 40 mph with no braking. I had someone look at suspension, tie rods, sway bar links, lower control arm bushings, exhaust system, however noone seems to be able to figure out where the noise is coming from. Any clues or ideas as to what to look at?? Thus far this is a mystery.
Can you make a YouTube video of the noise & post the link here?
Based on what you've already checked, I'd look at the CV joints.
Since you hear it when when letting off the accelerator, I would inspect the motor/tranny mounts.
In addition to CV joints at the wheels I’d look at the rear differential and the driveshaft CV/U-Joints from the front to rear. Drive shaft is easy. If you can grab it and turn it or get any play in it the your joints on it are worn. See if there’s any fluid leaking from rear diff.
