fdegree

I recently purchased a used 2010 F-150, XLT, 5.4L, SuperCrew with the FX-2 package (so it is Rear Wheel Drive - not 4WD). It has 120,000 miles. As far as I know, everything is original.
Here are the 2 problems I'm experiencing:
-- 1. When coming to a complete stop, there is a subtle thump that occurs just about the same time the truck completely stops. When I release the brakes and idle forward, everything seems normal. But, when I press the accelerator slightly, I feel that same thump. It's almost like something is engaging or disengaging. But, I can't tell if it is in the transmission, torque converter, brakes, etc. Anyone have any thoughts?
-- 2. When riding between 50 and 55 MPH, there is a vibration/shutter that occurs frequently, but not every time. It's almost like riding on a washboard. Anyone have any thoughts?

LimitedClear

Question 1 is more than likely the 2 piece drive shaft binding up. There is a TSB on it. The fix is simply putting some grease on the splines. I had the same issue in my old 2010 XLT.

Question 2 could possibly be the transmission needs a computer reflash. I believe there is a TSB for that issue also.

Hopefully this helps. Good luck.

mmgg

I in other trucks I've had the occasional vibration when the drive shaft spline was dry and sticking ,,,,,,,,,,,,,,,,and the stop,, start thump happened once to me. when a front brake caliper had the bolts come loose,,,another time also once when the front cv axle nut was loose.

fdegree

I have recently heard about this. Sounds this is most likely my problem. Even it isn't, it's simple and inexpensive to try.

This I had not heard about. I'll look into it.

Thanks!!!

Martian

Which makes me think:

1. Driveshaft u-joints. Around $10 each to replace.
2. Parking brake shoes hanging up. The scissor levers rust into one piece and the shoes start rubbing against the inside of the drum because they can't retract. Remove the parking brake, take the parking brake scissor actuator lever and beat it with a hammer to turn it back into two pieces, sand it down, grease, reinstall with new brake shoes (around $20).

fdegree

This is an interesting suggestion. I'll have to look into this. Thanks!!!

I've often thought it might be a tire...or perhaps a wheel out of balance...or maybe even a suspension characteristic combined with the lack of weight in the bed causing a funky "resonation". Anyway, I was hoping there was some history of this type of problem that might help give me some direction. If it's not drive train related, I can learn to live with it...I just don't want it to turn into something more serious later on. If I figure it out, I'll be sure to let everyone know.

Martian

My last vibration problem, after replacing the U joints and then the parking brake work I mentioned, was balancing the tires (again). That solved the remaining vibration I had. Just remember that tires sometimes need to be balanced more than once because every once in a while you get one that gets thrown off-balance by its own wear.

fdegree

***UPDATE***

Greasing the spline gear in the driveshaft solved problem #1 I described in my original post.

As for the vibration, as described in problem #2 - I haven't tried anything yet. I need new tires (20"), and I have a lead on new wheels AND tires for $750. So, I'm waiting to get those new ones and have them balanced and mounted to see if that helps. If it doesn't, then I'll pursue other ideas.

fdegree

***UPDATE***

Reference post #8 above for the fix to problem #1.

The vibration that is described in problem #2 of my original post, seems to have been solved with new wheels and tires. Occasionally, I "think" I feel some kind of vibration, but the circumstances are not quite the same, and what I "think" I feel is not as intense as it was. So, for now, I'm considering the problem fixed.

Thanks to everyone for there help!