Vibration ~20mph. If not needle bearing Or carrier bearing... ideas

I have a 17 DCSBOR with 5100’s and 888’s with a 3 leaf pack. I have the vibe/ faint rumble strip feeling from 10-20 mph, most noticeable around 15mph. It was most noticeable on deceleration at first but is getting pretty constant now at those speeds.

1. I of course did the easiest thing first in the process of elimination, the carrier drop. The Emu kit did nothing at all.

2. Putting it into 4wd doesn’t change it at all, so from what I’ve read that should indicate it’s not the needle bearings...

With what I’ve done above, can those 2 things be 100% ruled out?

What is this going to be most likely? Any advice is appreciated. Thanks.

 

Pinion angle.
More pronounced on deceleration due to springs loading up(a.k.a. axle wrap).

 

Thanks. How sure are you, need any more details?

 

I went through the same process as you and ended up fixing it with 3 degree shims.

 

+1 shims are definitely the easiest and cheapest next step.

 

Thanks fellas. Is there’s a diy etc for that? I searched and didn’t see one.

 

And the truck is going in for the leaf noise tsb. I though I had seen something about an axle wrap issue on the 3rd gens too but don’t see that either...is that a known issue I should have them look at esp since wrap was mentioned above?

 

Just undo your u bolts holding the springs to the axle then place the shim wedge in between the leafs and the axle. The wedge should be arrayed thinnest portion towards the front and thickest portion closest to the rear to angle up the pinion.

 

Thanks. There’s only one size to get?

 

2.5 or 3 degree. There are other sizes, but start with one of these. You may accidently go too far, but I have yet to hear of anyone on TW going larger than 3 degree shims.

 

Thanks. The axle wrap is even an issue with stock height trucks too right?

 

It definitely is. My truck has had the same vibration since day one. I'm going to be installing my lift this week, I'm hoping the new rear shocks will dampen the vibration a bit, maybe with a combination of the new shocks plus aal.

 

Good info here. I recently lifted my truck also and I get a vibration right at 10MPH. I bought the OME carrier bearing drop which didnt do anything at all. Next step is the axle shims, just wasnt sure exactly what size to get. It seems like most people run a 3* shim with good results.

Now, since my U-bolts and nuts are super new (less than 2 weeks at this point) it should be ok to just loosen them enough to put the shims in and not have to replace them right? Ive heard that once you loosen the nuts from the U-bolts its just best to buy new ones since there is a possibility that they have stretched.

 

How did you determine that 3* would be the best bet? Did you get under the truck and measure angles and figure it out or just guess? This is the situation im in right now too.

 

Just an educated guess based on what I had read here. Got lucky and all vibrations are gone!

 

What’s your lift set up?

 

Wondering too.

 

What’ll be the issue if they stretch?

 

Thanks. What’s your
Lift setup?

 

I wouldn’t let this worry you. 90ft/lb and call it a day. You are more in danger of boogering up the fine threads from an impact gun or grit on the threads from the nut than anything associated with bolt stretch.

2nd Gen, so maybe apples and oranges but extended travel up front with aftermarket UCAs, no diff drop, no carrier bearing drop, ECGS solid spacer. 15 leaf AP EXPO in back with 3* shim, shackles flipped with 12” stroke icons.