Help me diagnose a cluck after a lift kit!

[jschwerdtfeger]

I have a 2021 XLT 4x4 with 20k miles on it. I just installed a 3" rough country vertex lift and have been experiencing the dreaded intermittent clunk (for the last 1000 or so miles). The clunck occurs when accelerating from a stop and seems to be more prevalent when the truck is cold. I can't exactly tell where the noise is coming from, but is sounds like the rear. I've gone through and retorqued everything, so all good there. I've also hopped on my bumpers and cycled the suspension to see if I could reproduce it, but no luck—it seems to only occur under acceleration load. To be more specific about the noise, it almost feels like a shock is sticking and releasing, or a brake pad is stuck then releases (I inspected all the brakes, all good there, too)—kind of a catch-and-release type sound and feel. It's not severe, but definitely annoying.

I'm kind of thinking it's maybe one of the rear shocks?
Any suggestions would be greatly appreciated.

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[Facemelter]

Just for grins and giggles, you can check if the truck has a two piece rear drive shaft. I know on the 12th gen they had a rear two piece slip yoke that would clunk like that on take off. I fixed mine with the little kit from Ford.

 

[jschwerdtfeger]

Just for grins and giggles, you can check if the truck has a two piece rear drive shaft. I know on the 12th gen they had a rear two piece slip yoke that would clunk like that on take off. I fixed mine with the little kit from Ford.

Mine's one of the big aluminum single piece guys (has a slip yoke but no carrier). It could be the slip yoke, I hadn't thought of that.

 

[Iroquois Cage]

Sounds like U bolts. Im guessing you torqued the piss outta them? As for fronts- i feel like people never tighten the Tie rods and end links enough. Did you loosen the axel nut for front strut clearance? I know that's FRONT, but it can cause a sound similar to what youre describing.

 

[SpaceWhiteF150]

When mine was leveled with factory UCA’s there was slight popping sound from the front end, now with the ICON UCA’s the front end is tight and silent!

 

[jschwerdtfeger]

Sounds like U bolts. Im guessing you torqued the piss outta them? As for fronts- i feel like people never tighten the Tie rods and end links enough. Did you loosen the axel nut for front strut clearance? I know that's FRONT, but it can cause a sound similar to what youre describing.

I'm going to grease the slip yoke with some PTFE and see if that solves it, everything is torqued to spec.

 

[Graygoose2021]

Exhaust isnt near anything is it?

 

[jschwerdtfeger]

Exhaust isnt near anything is it?

nope.

 

[Rockman5159]

I have a 2021 XLT 4x4 with 20k miles on it. I just installed a 3" rough country vertex lift and have been experiencing the dreaded intermittent clunk (for the last 1000 or so miles). The clunck occurs when accelerating from a stop and seems to be more prevalent when the truck is cold. I can't exactly tell where the noise is coming from, but is sounds like the rear. I've gone through and retorqued everything, so all good there. I've also hopped on my bumpers and cycled the suspension to see if I could reproduce it, but no luck—it seems to only occur under acceleration load. To be more specific about the noise, it almost feels like a shock is sticking and releasing, or a brake pad is stuck then releases (I inspected all the brakes, all good there, too)—kind of a catch-and-release type sound and feel. It's not severe, but definitely annoying.

I'm kind of thinking it's maybe one of the rear shocks?
Any suggestions would be greatly appreciated.

I have a 2021 FX4 rcsb one of the rattles in mine was the gasoline venthose was out of bracket slapping the bed side underneath. I also can hear my tailgate rattle if i hit a big bump

 

[jschwerdtfeger]

And problem solved. PTFE Ford greased the slip axle, and the clunk is gone ?

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