Help with Diag. 2015 DCSB

I’m hoping someone can help me with some diagnostics. I have a Bilstein 6112 lift on my truck, 120k miles. I have noticed a progressively worsening symptom. I just took it to a shop and they couldn’t find anything wrong.

timeline of the issue:
1. Noticed vibration only at 40mph
2. Noticed a clanging when accelerating at low speeds that would go away after passing a certain speed
3. Present: notice both a vibration/shake up through 50mph accompanied by a squeak/bird chirp sound. If I stop accelerating at any speed along the way both vibration and sound go away. They restart immediately when hitting the accelerator again. If I hit cruising speed or drive for a while I notice both things go away completely, until I come to a stop again and it restarts.

the shop only rotated my tires. They didn’t have really any other clue. Had them check the idler pulley and they didn’t think there was any issues.

 

Chirp/squeak makes me thing u-joint(s). Does the frequency of the noise change as you go faster or slower?

 

After about 20 mph it starts, it gets worse as I accelerate until about 60. But if at any point I let off the gas it stops completely. So it doesn’t rumble or chirp if I’m coasting

 

If that’s the original belt, I’d change that old thing.

 

If the noise is there & you can replicate it, find a real shop that has a clue & does real automotive repair type stuff....
Could still be u joints regardless that it doesnt do it while coasting...

Could be anything, a tech need to isolate & pinpoint the noise.
Figure out where its coming from & not just dice rolling.

 

Well was hoping someone would know but I know that’s hard without hearing it. Little update, the chirp almost entirely goes away the more I drive the truck. I don’t drive it a lot in general. However the shake/vibration happens from 20mph and up. And seriously, when I step of the accelerator it immediately stops, and immediately restarts when I hit the gas. Kind of reminds me of my busted motor mounts on my old jeep. Could it be that?

 

I'm thinking U-joints also.
Grab ahold of the rear driveshaft next to each U-joint and yank back & forth on it looking for any play in the joints (be sure there's no tension on the shaft though... Have the truck in neutral, brake applied and the wheels chocked... Alternatively, you can also jack the rear wheels up off the ground).
You're looking for any movement besides rotation... So up/down, in/out, etc. Also any clunking that is not related to rotating it. There should be none.
(a little movement in the rubber around the center carrier bearing is OK, but if it's very loose or sloppy, then that could be your issue too).

 

Thanks everyone, I am going back to the shop. They are looking into U joints and axles. I will get back to everyone with an update

 

U joints and center bearing. Thanks fam!

 

Personally I'd start with the u-joints before convincing myself the carrier is bad too.

 

While the driveshaft is out and with 120k miles on it.. Id say its smart to do them all at the same time.

 

Perhaps, but the carrier is significantly less fun to do than the u-joints. If I were turning my own wrenches I'd do them incrementally. FWIW I don't consider 120k miles to be particularly significant.