I have a 2018 super crew FX4 that I bought new last November. This summer I started to notice thumping/creaking noise when driving down farm paths. I could tell it was happening when the rear suspension moved over uneven ground. I suspected leaf springs but was not sure. Lately it has gotten much worse. I jacked up the rear end and using a screw driver, separated the springs allowing access to the white nylon pads between the springs. Using brake cleaner and a tooth brush, I scrubbed the gunk from the pads and springs. Once dry, I applied a little lithium grease to the pads and where the springs are rubbing. Problem solved. No more clunking or noise from the leaf springs. Next time, I'll try just cleaning and no grease to see if that works. The grease may attract dirt and cause more noise. It almost looks like Ford put some kind of grease or coating on the pad/springs where they make contact.
Hope this helps someone else as I know the noise can be very annoying. It seems I read somewhere you can get thicker nylon pads that may keep the springs from rubbing. That may be the real fix.

 

Can you post a picture of where exactly you did this? I am getting the noise as well. TIA!

 

The white nylon pads are between the long springs, one pad up front, one pad at back of the spring set. If you look at the springs, you can see the pads on each end of the spring set. If you take the weight off the axle, you can use a flat screw driver to separate the springs to get to the pads and clean/grease them. Sorry, don't know how to post a pic.

 

After 3 weeks, leaf springs are still quiet. No more creaking/thumping noise from rear end.

 

My 2018 has 13k on it and within the past 2k mikes I’ve noticed I’ve been having a squeaking/clunking noise in the right rear. Sometimes it will pop loudly when going down or up driveway curbs as well. Recently it’s been squeaking constantly at slow speeds. Anyone have any ideas? I think a trip to the dealer is in order. Thanks in advance.
video:
Squeak/clunking right rear

 

Hey Jono, I had exactly the same issue, and just wrote down how I fixed it on a post right below this one. First, I duplicated the noise by putting pressure on a corner of the rear bumper with my hand. Heard it below, but to find exactly where, got under the truck, and told my wife to move it for me. It wasn't the nylon piece in my case, but one of the leafs itself. And surprisingly, I could duplicate the noise with my hands by just pushing up on the spring. Then it sounded again when relieving the pressure (it doesn't need much, by the way). It must be a metallurgy issue, at least for that noise. It's pretty subtle, but it annoyed me when backing up and stuff, since I could hear it. I inserted a piece of hard rubber between the leafs with a screwdriver, and problem solved, at least for now .

Having said the above, if it comes back, I want to fix it the right way, which to me is to insert a square of hard rubber on top of the hard plastic isolator, which is exactly what freaking Ford should have done. Hard plastic doesn't absorb vibration. And apparently there's not enough tension on the springs to prevent it. Maybe if the isolator was thicker it'd work. But there's no redesigned isolator, so why replace it? It'd be exactly the same. And if you change the damn thing, it might have the same noise, so I'd just fix it myself if needed. I'd just need to source a sheet of hard rubber, and cut the pieces to size as needed.

 

So for those that have this noise I just had the rear leafs on both sides replaced under warranty. Took two visits to the dealership before it happened. First complaint was in November of last year, second was this May. First trip in they "could not replicate" which was ridiculous. Second trip in same thing except this time the noise was so bad people would tell me about it in parking lots. Refused to take the truck back and had to take a ride with the service manager and the tech who didn't hear anything abnormal. Didn't make it out of the parking space at the dealership before the manager turned and looked at the tech and said "really?". Truck sat in the dealership for a week while they took various parts off and drove it till they figured it was the leaf springs. Ordered those and installed and the tech that originally didn't hear a problem told me the springs were buckled and were a factory defect. New springs now under warranty and problem is 100% gone. If your truck is still under warranty make them fix it right.

 

Mine was caused by the clamp, I use anti seize and it never came back. It was rubbing on the side and causing a creeking noise over angled surfaces.

 

I have a 2018 with 8000 miles and a sort of rattling sound. It reminds me of my wife's SUV when the hitch is in the receiver. Hers is loose and rattles around when you go over bumps.. Same sort of noise in the back of my truck somewhere I only hear going slow. I was at the dealer last month getting an oil change, Engine re flashed for oil consumption and and 10 speed trans flashed as well with updates. I mentioned the issue to my service writer. As soon as he drove it to the back for work he heard the noise and acknowledged something was wrong. He called and did not say why but they needed to replace the rear leaf springs and had to order the parts. I was leaving town for 6 weeks for work a few days later so did not leave it there and will bring it back in a few weeks when I get home to have them replaced. I will keep ya'll updated as I am curious what the problem is and why they have to entirely replace the leaf springs? To be continued.

 

My 2018 is making the same creeking, squeeking noises in the rear. My truck is lowered with the Belltech kit so I doubt Ford would be willing to do anything about it. Last week I took the rear shackles off and greased them with waterproof grease. That didn't help. Yesterday I jacked up the rear and removed,cleaned and reinstalled the round rubber isolators (I guess that's what they are called). I also took a screwdriver and separated the 2 upper leafs to access the white plastic sliders (or whatever they are called). I cleaned them but didn't remove and clean throughly. There is less noise coming from the rear now so I suspect this is my problem. Think this weekends project will be to do a through clean and inspect on this. I will also check the clamp on the sides of the springs. Hopefully this will fix the problem. It's annoying to say the least.