I have had a wobble/chatter when braking for awhile. Had multiple people tell me by brakes we’re in good shape. I dropped my pickup off at a shop to get the brakes replaced while I was working, and the shop said it seemed to be stuck in 4WD. Dial is turned to 2WD and I don’t feel any type of binding while driving/turning. As soon as they got it on the lift, both front tires spun in unison. Any known causes for this? Fixes?

 

Hmmm, another 1977? Nice.

 

Just to be clear, that's @artsr2002 way of saying we're not all clairvoyant enough to conjure up a vision of what truck you are asking us to help diagnose.

 

It's a 2017.

 

Fairly normal for any 12th/13th gen F150 to do that. No vacuum, they all revert to locked IWE. I am assuming the engine was off?
I'd suggest taking it to a shop that is familiar with the Ford 4X4 system.

 

 

But if you're sincere, then, JohnDay's answer is more than likely the correct response to your post. Cheers.

 

I had something very similar in my 2015. It took me a while to figure out, it ended up being a dry half shaft spline shaft on the axle side, not the hub. If I remember, I just needed to buy new C clips for the shaft and a retaining nut on the hub, probably get a dust cap since you'll destroy it. Greased her up with the correct grease and threw back in and my wobble and chatter was gone.

My understanding was as the CVT's rotate, that shaft slides in and out due to the design of the CVT rollers, and that shaft when it's dry is binding and pulling on the rest of the shaft and popping in and out instead of running smoothly.

 

Until something can be verified, this is one area a wobble can come from.
When applying Braking and a shimmy occurs along with worn suspension, it can be front Disc/s are warped, Pads worn at an Angle, Caliper Pins frozen or any combination of these effects.
The IWE are normally locking the front Hubs without engine vacuum to unlock them.
Look at the smaller Vacuum hose at each front area.
There is no >pressure pump< to engage them, but there is engine vacuum to disengage them when running. Thats why it seems backward but that's the way it has to work for auto operation to work on the fly by removing engine vacuum for >intentional lock-up.
Good luck..

 

I also wanna add if you have the transfer case with auto four-wheel-drive, your front axle assembly will always be spinning whether hubs are locked or not