I know I need to replace my clunking bushings, but this sound is more of a constant "thud.thud.thud.thud...". It comes and goes but anytime it does come a small upset in the momentum of the car from the gas or brake peddle will stop it. It only comes on (or I only hear it) when im crusing at under 40. It's wierd, It's very hard to replicate on purpose. I don't remember feeling anything when it happens, but it's happend maybe a dozen times now, most normally when I'm idling down my road at under 20...

Anyone know what this might be?

 

check around loose suspension pieces. Also, is there enough differential oil? Are the rear axles in good shape? Spray some WD 40 around the wheel / suspension joints to see if anything helps. Lastly, is this just a sound or also some bouncing? If bouncing, maybe it's wheel balance, not likely but worth a shot.

 

Watch the WD-40, it's a solvent.

 

I haven't found any loose peices, but I have no idea what my diff fluid level is at. As for the axles, they are there, heh, I could look more carefully tomorrow. It's just a sound, I don't really feel anything.