Sorry, forgot to post vehicle. 2007 - F150 FX4 4x4, 5.4L, 65,000 miles. I have a clunk that I sometimes get while driving 60 mph. It's almost like the rear end went over a sharp bump in the road, but it's not due to the road and is not associated with a transmission shift (automatic). It feels like something has some play and then engages, or something slips then engages hard. I've also noticed that I aslo feel a slight vibration while driving lately. It's not occuring when I start from a stop, or when I start and turn. Just when I'm going along at highway speed, but usually happens when I'm going up a slight grade. Any ideas?

 

Kinda hard to help you when you don't provide any details on what your vehicle is..........

 

im gonna take a shot in the dark here and say its a failed Ujoint

 

Would I not get the typical "squeaking" or "chirping" when starting out if it was a U-Joint? Or is that old school symptoms. I have not had any of that occur.

 

Might even be a low grade misfire or an intermittent coil failure. Try and re-create it as much as possible and see if a CEL pops up. Patman is probably on the right track though with the u-joints

 

The U-joints are tight. No movement whatsoever when I try to turn the shaft. I never thought about the misfire possibility. I don't have a service engine light on, but I'll plug in a code reader and take a look.

 

my truck has started to do the same thing. up a slight grade at 60mph or accelerating slightly from 60-65. I was thinking tranny bc my truck will down shift if i apply just a hair more gas. torq converter? tried for about 15-20 mins to get it to trow a CEL but i got nothing. and it did it about 3 times in one acceleration. my truck has about 71500 miles

 

To RiverRat,

It sounds like the same thing, and happens in the same way you mentioned,but I can't get mine to repeat that often. It might happen only once every couple of weeks. I do not have any error codes showing up. I'll let you know if I figure it out. Please let me know if you do too.

 

I don't know if this is good news or bad, but I had the transmission fluid changed (flushed... however they do it with the machine at the Ford dealer) and it hasn't made the clunk since.......

 

i was thinking it could be the torque converter making the shudder

 

I feel like I have the same issue with my 04, the low grade misfire from all the posts I've read. How does one diagnose which cylinder its coming from if it won't throw a code?

 

Mine will made a clunk sound as well when I am starting from a stop or very slow accell. Seems when the load is at its highest it makes the noise.

05 f150 fx4