Hello all, noticed a strange "shudder" today while driving looking to get some advice as to where / what to look for.

First let me set the scene. The transmission shifts strong through all gears without hesitation, studder, or hard shift. Motor doesn't skip a beat through the entire RPM band.

This "shake" last about 1 second and happens only when accelerator is rapidly pressed, no more than 200-300 RMP Jump. I can replicate the shake multiple times in a row on between 50-60 MPH. definitely not motor related and most likely not transmission related. The truck is an 02 5.4 4x4 with 160k.

I think the issue could be bad U joints in the drive shaft, not quite a clunk and doesn't last long. Best description I can think of is something feels out of balance for a split second.

note: U joints are original is 160k an amount to cause them to fail? No up and down movement in the drive shaft, but lots from left to right and the joints.

Thanks in advance!

 

They're probably bad. Mine started squeaking real bad first before they went bad. New front and rear MOOGs are only $20 I believe for both. Pretty easy changing them. Mine went bad at 135k but I noticed the back joint had already been changed at some point so my trucks on its 3rd rear u joint now

 

At that speed i think COP.

 

Could be Rear end. Whens last time you changed gear oil. It will do a little worst if you are towing. Make sure to add the additive with gear oil, if it may be that.