You might also want to check the universal joints in the drive shaft. If they are worn, they can deliver the "clunk" noise you are experiencing.

In the automatics, have the fluid flushed/changed if your mileage is getting up there. Pull the transmission dip stick and smell it. Does it have a burnt smell to it? Does it still feel slippery? After around 60k, you want to get that transmission oil flushed (dropping the pan and replacing 4 quarts is not good enough). Take it to a transmission shop where they have a flushing station. They connect up to the automatic transmission lines and run the engine, pumping the old fluid through a flushing station, and it installs new fluid.
Not sure if the new trucks allow for torque converter access (do the torque converters on these trucks have a drain bolt?).

 

I am new to the site. I have an 05 Screw FX4. I had the same issue with mine since I bought it new finally @ 17,500 I took it in to the dealer. They had to pull the driveshaft and regrease the slipyoke due to some D.S. got out without any grease. 3,000 miles later had the same issue so I decided to take it back to the dealer there is a dealer notice kinda like a field service action plan if anyone has this issue the dealer is supposed to fix it. So the second time they decided that they would clean out the grease ,regrease the S.Y. and then proceed to clean and realign my rear suspension(i.e. my shocks,springs,springpads, and u-bolts) made sure all was tight and clean,aligned and hasn't happened since.I have more info if anyone needs more insight just drop me a line at bgladimnotyourkid@yahoo.com hope this helps.

 

getbit96,

Good to hear your problems were fixed. I sent you an email, please send the additional info.

 

email came back as undeliverable.

 

Sorry if the email didn't work just wanted to say that the D.S. in ? were mostly steel one piece mostly KA and MA sticker part #'s. These are the ones mostly with the grease issue but could be any one piece steel. Never really had any issues with the aluminum one piece or 2piece running low on grease or non greased slipyokes. Just FYI I used to build these and it was because of management trying to say a few pennies ended up costing em.

 

I must have made a typo with your address. Thanks for posting the extra info.

 

Your welcome I hope this helps. Goodluck.

 

My 2005 F-150 does the same clunk when I accerlerate slowly, usually when shifting into second. This is the secodn F-150 I ahve had that does this. The first one was diagnosed by Ford and they claimed they could find nothign wrong (Galpin Ford VAn Nuys, CA). A tranny shop said it was a shift modulator but I had to seel it before i could get it corrected.

I will taking my 2005 to a dealer to get it checked out and will post the results.

I notice there are no Dealer mechanics posting replys on this site. Is there a better F-150 site to get answers from?