Intermittent Shake After Lift

Hello fellow Tacos. I've got a '15 AC SR 4x4 6 spd and a while back I put on Bilstein 5100's (all around) with stock springs and the Deaver "overload replacement" leaf set. The truck drove fine, albeit a little stiffer than I'd have cared for. A month later I put Firestone airbags on it and now I have an intermittent and inconsistent shake/vibration. It literally comes and goes with no notable explanation. It feels like an out-of-balance wheel when it's happening, but how could that be, given the inconsistent nature of it? Any insight would be greatly appreciated.

 

Is it consistent depending on aiŕ bag pressure? Road types?(pavement/concrete). Throttle Pedal tip in/out?

 

Road surface doesn't seem to make any difference. The one thing I failed to mention (which is why I say it feels like an out-of-balance wheel) is that the vibration/shake is speed dependent. The faster I'm traveling, the higher the frequency of the shake. I haven't messed with airbag pressure. After installing the bags, the rear sat higher overall (than before airbag install), and the passenger side sat higher than the driver. I added a little pressure to the driver's side just to sit level but the passenger is at the recommended minimum.

 

I got some new vibes after putting the same shocks on (1.75” lift on front). Ended up being worn wheel bearings that became more noticeable post-lift. I’d start w/ a simple home test to try and rule those out.
https://www.youtube.com/watch?v=vJYDGWEwhEk

 

@IA DIY Thanks for the advice. I'll give that a check when I get a chance. The truck only has 84k on it but I suppose anything's possible. The last bit of info I realized I failed to share is that the tires have about 40k on them and are quite worn/due for replacement. In my head that wouldn't account for the vibe coming and going but figured I should throw that out there. Don't want to put new shoes on it if there's something wrong that's creating or accelerating wear.

 

Try putting 400-500 lbs of ballast (sacks of concrete, steel weights, etc.) in the back of the bed & see if that softens up the ride. Might even reduce vibes a bit.

I put heavy Deaver springs on my Taco + FOX 2.5 PE DSC's on all 4 corners, and if I don't load it heavily enough, it rides quite rough.

I have more or less the same truck, a 2014 AC 4.0L 4x4 6spd MT, with the same ARB front bumper, and an A.R.E. contractor cap on the back. Lift is at about +2 to +2.25" front and rear and I have had only the slightest, barely-perceptible vibes from time to time.

 

Aaaaaàh... was the two piece driveshaft pulled apart? Timing...

 

I'll give that a go and see if there's any change. Thanks for the reply.

 

No, the drive shaft was not pulled apart. I've seen a fair number of folks talking about the carrier bearing needing adjustment/drop. Any thoughts out there on that component possibly being involved?

Also...timing?

 

I was referring to 2 piece drive shaft timing. They have to be "timed" properly or it will cause premature wear and or vibration. Google driveshaft timing.

 

Does the vibration go away when you put it in 4WD? If so it's more than likely your needle bearing.

 

The carrier bearing on the driveshaft spec is 1/4" of play. Roll under your truck and give it a shake. The drop might help too.

This is too much:
https://youtube.com/shorts/jzabcym5Lek?si=F76xqghVHMsEyeI9

 

And to clarify, it's not just 1/4" of loose/floppy play. It should be 1/4" of firm play that is fully restrained by the soft rubber of the large bushing inside the carrier bearing holder/housing. (I.e. the rubber in there should not be excessively cracked/shrunken/hardened etc.)

 

I had, and remedied that symptom already with the ECGS bushing. This vibration is quite different than that was.

 

I'll roll under there this evening and take a peek. Thanks for the video example.

 

Also you can narrow down where it's coming from by sitting firm in the seat, putting your hands at 10 and 2 (like on a clock) and going for a drive. If you feel a vibration more in the seat/floor it could be coming from the rear end. If you feel it more in the steering wheel, it could be from the front suspension.

What speed do you notice the vibe?

 

When it's present, I believe it's at all speeds but doesn't really become that noticeable until about 35-40. At 70-75 it's the most prevalent and also the highest frequency, as it's relative to speed. Here's a theory I have and would be curious to hear if folks think I'm crazy, but the front passenger tire (just confirmed today) has something inside it. I'm fairly confident it's a piece of the pressure sensor, since this is the second time I've had something loose in a tire and the tire shop fished the first one out. So my theory is that it acts like a wheel weight, and depending on where it gets pinned against the inside of the tire, it either produces the vibration or it doesn't. Am I crazy? I know it's very small but...‍maybe?

 

Sounds theoretically possible, although the piece of TPMS that broke off may or may not be heavy enough to make a difference. But it's certainly a candidate for the apparent randomness of the problem.