Hello,
I drove the following truck yesterday:

2018 F-150 XLT Screw, 5.5’, 4 x 2
3.5L EcoBoost engine
3.55 axle
18” wheels
Max tow package
55,000 miles on it (personal ownership, not commercial)

I noticed a very slight shudder or vibration only when turning a corner, and accelerating about halfway through that turn, as you normally do. It did it when turning left or right, and it feels like it’s something in the body of the truck (as opposed to say, the steering wheel). I did not notice it on the straightaway or when going around a curve. Shifts smoothly, accelerates smoothly, otherwise handles well. Nothing obvious with the tires. Salesman wasn’t sure, but thought it was related to the “curve control” function of the truck, which I don’t understand, but somehow corrects for motion on a curve. Basically, he said, the truck was telling me to be more gentle when turning a corner. I did not think I was turning sharply and I certainly wasn’t punching the gas pedal. However, it’s been a long time since I’ve driven a heavy vehicle with rear wheel drive (used to full size car, but 1000+ pounds lighter, and with front wheel drive)—so, maybe I do need take it a little easier on turns?

I would appreciate any thoughts/comments. Thanks in advance!

Karen

 

Run as fast as you can away from that truck, dealer & salesperson.

A normal turn in an F150 feels no different than any other vehicle.

 

I’m sorry, I should have stated this: Exhausted brain (no excuse) already bought it. 😥

 

That's unfortunate. Sounds like you bought a truck with issues.

 

Any thoughts on what those issues might be?

 

Yes, details do matter, don't they.

If you have no confidence in the selling dealer (I wouldn't, based on your story), take it to a known trusted competent mechanic. You can guess & wonder as long as you like. Take it to a competent shop & get it diagnosed & fixed.

Good luck!

 

It's most likely the rear end.

Had that problem on my 06. When they change the oil there is a "friction modifier" additive that they are supposed to put in it and didn't and mine was doing exactly what you describe. It is possible that they used it for a boat and got some water in there. Happened to my dad on his 09 and had to replace the rear end.

Get it checked SOON!

 

Does the truck have "lane assist?"

When we first bought our 2019 Lariat, I had to move over partly into the other lane to give room to a car on the shoulder...felt like I was crossing rumble strips...brrmp, brrmp, brrmp...yet there weren't any. Happened in a corner too...WTF? Finally figured out that it was the "alert" feature of the lane assist."

 

No friction modifier on these (no LSDs) but rear end would be my immediate concern. I would check (or have checked) the rear diff for proper level and any contamination. In fact, I would change the fluid while I'm changing every other fluid and filter on the vehicle (this is always a good practice with used vehicles, since you have no idea how they've been treated/maintained).

 

My first thought would be tires that are possibly underinflated or an alignment & treadwear issue.
Worn rings in a rearend usually howl a bit at higher speeds, especially when accelerating slightly while going at highway speeds.