92 Jeep Cherokee Laredo, 4wd, 4.0L straight 6.

Sounds like it's coming from under the floorboards behind the motor. When I stop, and then take off, I get this light thud like if the trailer tongue was sliding in then out and catching, but its not. If I ease into the throttle, I can postpone the thud. If I accelerate harder, it happens right away. Only happens are starts after a stop.. Any ideas? Thank you

 

Check your motor and transmission mounts.

 

x2

 

After checking the motor and trans mounts also check your U-joints.

 

also... how much play is in your hitch? If your hitch insert is loose enough around the pin it will slide back and go "thud" when you take off.

 

If your trailer is equipped with hydraulic surge brakes, it's most likely the actuator releasing as you pull forward. Perfectly normal.

 

This. Depending on how old your trailer is, and how you have your brake controller set, electric brakes can do this to.
Also, that extra mass is going to push on the Jeep at least a little. When you brake it will compress the front more than normal, and just driving around, the back end is lower, so what is the general state of your suspension?

 

if all of those check out, check your transfer case fluid. My girlfriend's dakota would do exactly what you are describing because her transfer case was low on fluid, not lubing the slip yoke properly.

 

Chrysler clunk maybe?

 

Thanks for the replies guys, I'll try to check the mounts. I'm not sure what I'm looking for, but I'll try to look it up. If anyone has any pointers to locate these and what they look like. I'm guessing rubber blocks?

There isn't much play in the trailer tongue. This would be the natural suspect and most benign cause(also what my girlfriend though it was), but I don't believe its that, the sound and feel seems more toward the engine and there's just not much slop.

No brakes on the trailer. It's a 16' Starcraft, all aluminum. I don't have any issues with stopping power.

The harder the stop, the longer and harder the thunk. If its a really light stop, its a really light and quick thud. Seems like on harder stops its a more pronounced thud. Not proportional though. It only thumps so hard and loud so I'm not worried about anything falling out quite yet I'll try to get more info

 

could just be rear brakes sticking... Mine does it even when not towing