Driveline Vibrations - 23 GX

[GXFamily]

TLDR: 23 GX with an Ironman lift - chasing a driveline vibration that has recently popped up.

The lift was installed when the vehicle was new, this vibration has become slowly more noticeable within the last 10,000 miles. There was no vibration when the lift was installed. The vibration occurs between 65-80mph - Under 65mph it does not exist and over 80mph it does not exist. It is most certainly a driveline vibration as it is not only a deep harmonic audible noise, it can be felt in the floorboard and the rearview mirror shakes/vibrates in-sync with the harmonic audible noise.

Vehicle:
2023 GX with 20,000 miles.

• Ironman 2.5" Lift
• Ironman UCA
• Ironman adjustable panhard bar
• Dr KDSS panhard bar correction kit
• Ironman rear swaybar spacers
• Nitto 285's on SCS wheels.

I have checked / replaced the following:

• All suspension TQ has been checked, verified and marked
• Alignment is dialed in - see attached.
• Driveshafts are greased properly.
• CV axles are tight, no play and no tears/rips in the boots.
• Checked wheel run-out
• Tires have been force match balanced. All tires are under 10lbs of roadforce.
• The wheel to hub mounting points are clean and free of debris. Each mounting surface has a light coating of nickel anti-seize
• New lug nuts TQ at 90-ft/lbs
  • Grasping at straws here.
• Rear driveshaft replaced 1000 miles ago with #37110-60A40
  • This did eliminate a minor clunk when shifting from park.

I noted the following today:

• Rear driveshaft angle @ 10.1 deg
• Front driveshaft angle @ 2.1 deg
• LT CV axle angle @ 5.2 deg
• RT CV axle angle @ 9.1 deg

The floor to fender measurements are as follows: Both sides are within 1/8 of eachother.

• Font: 38.25"
• Rear: 39"

I have access to another 2023 GX with the same exact setup, with different wheels of course and more miles. No vibration and smooth as silk. I even swapped the wheels/tires and I still have the vibration issue. However, the only difference I noted between the vehicles was:

• Rear driveshaft angle @ 8.5 deg
• Front driveshaft angle @ 2.4 deg
• LT CV axle angle @ 5.4
• RT CV axle angle @ 7.8 deg

I am becoming increasingly frustrated, what am I missing or what else should I be looking at? I am desperate as this has gotten worse over time and I'm afraid something is going to break.

 

[Rednexus]

The only items I think that could cause this would be 1) tires and 2) driveshafts. 99% of the time my money would be on tires, yet you note yours have been balanced. It may be worth inspecting them more to make sure the wheels/tires are not damaged (i.e., a bent rim, a slipped belt) in a manner that the tire shop may have missed (they don't always have the best labor).

Other than that, you could also try to isolating the source of the vibration temporarily removing the rear driveshaft, locking the CDL, and driving it (basically as a front wheel drive GX). If the vibration stops, then it is the rear driveshaft issue (it's possible that it was installed with the slip yolk not clocked in the same orientation as it was balanced). If it keeps vibrating with the rear driveshaft removed, you could do the same thing with the front driveshaft (leaving you as a rear wheel drive GX), in order to eliminate the front driveshaft as the source of the vibration. It's not hard to pull the driveshafts with a 14 mm socket and open end wrench.

If it's still vibrating after trying this, then it almost certainly has to be a wheel and tire issue. I can't really see a CV joint or something in the rear axle developing a vibration - especially on such a new vehicle. My rig certainly does not do that, and I'm up higher than you are.

 

[GXFamily]

The only items I think that could cause this would be 1) tires and 2) driveshafts. 99% of the time my money would be on tires, yet you note yours have been balanced. It may be worth inspecting them more to make sure the wheels/tires are not damaged (i.e., a bent rim, a slipped belt) in a manner that the tire shop may have missed (they don't always have the best labor).

Other than that, you could also try to isolating the source of the vibration temporarily removing the rear driveshaft, locking the CDL, and driving it (basically as a front wheel drive GX). If the vibration stops, then it is the rear driveshaft issue (it's possible that it was installed with the slip yolk not clocked in the same orientation as it was balanced). If it keeps vibrating with the rear driveshaft removed, you could do the same thing with the front driveshaft (leaving you as a rear wheel drive GX), in order to eliminate the front driveshaft as the source of the vibration. It's not hard to pull the driveshafts with a 14 mm socket and open end wrench.

If it's still vibrating after trying this, then it almost certainly has to be a wheel and tire issue. I can't really see a CV joint or something in the rear axle developing a vibration - especially on such a new vehicle. My rig certainly does not do that, and I'm up higher than you are.

The tires are new with 1500 miles. I started with BFG, switched to Duratrac RT. Wanted a new look and now I'm on Nitto Ridge Grapplers. The vibration slowly started with the DuraTrac RT and has continued to get worse, even with the new Nitto RG.

The driveshaft is new, I put it in a few hundred miles ago. OEM unit. I swapped the old driveshaft back in and no change.

I noticed this morning I'm now getting an audible deep rumble between 38-41mph and it goes away above that. Increasing speeds to interstate up to 64mph it is smooth as silk. The moment I hit 65+ the vibration starts and increases with speed.

It is certainly not a wheel shake as it is simply too fast. I may try swapping my OEM wheels back on and see what happens. Those have 20 miles with the OEM Michelin's.

When I swapped the driveshaft, I made sure the paint marks on the driveshaft aligned with the mounting points of the TC and rear differential. The driveshaft was not taken apart, and is in the correct phase.


Is it safe to drive at interstate speeds with the rear driveshaft removed? That sounds a bit risky. I'm about 10 miles to the interstate and at least another 5-8 miles before I can get out of traffic and up to a constant speed.

 

[TheBussman]

try driving on only one shaft at a time. your driveshaft measurement doesn't really tell a whole lot, more important to know the angles of each u joint, what is the angle of the rear pinion or the transfer case? If the vibration still persists need to find a shop that is proficient in diagnosis with an oscilloscope. I can graph out and measure the frequency of the vibration to help isolate the the noise/vibration/harshness.

 

[Rednexus]

Is it safe to drive at interstate speeds with the rear driveshaft removed? That sounds a bit risky. I'm about 10 miles to the interstate and at least another 5-8 miles before I can get out of traffic and up to a constant speed.

It should be no different than driving a FWD car. But, obviously it's your rig so do what you are comfortable with. I drove my rig around with no front shaft for around a week at it was totally fine.

 

[GXFamily]

I am positive it is not the wheels/tires. I swapped on a known good set of 285's and I'm getting the same issue.
Hubs were cleaned again with a wire brush to ensure a perfect mating surface.

Also swapped in the original driveshaft and no difference.

Narrowed down the vibration is exactly at 35mph --> 38mph and begins very mild at 65mph, increasing to a maximum at 77mph where the rearview mirror vibrates. Disappears at 78+.

There is a distinct low rumble and almost sounds as if you are driving over rumble strips on the highway, pulsating.

All that is left that spins at this rate is the front driveshaft or CV axles. Everything is tight, zero play/noise in the hubs or driveshafts and the front CV axles have no play either.

 

[Stonefoot72]

I had never had problems with acorn lug nuts on my GX, but bought my wife one and replaced stock with new wheels and tires and picked up a vibration. Chased it for weeks. Finally decided to get road force balancing (which can solve vibration issues on chunky off-road tires that even perfectly balanced centrifugal balancing can't fix) and the tech said "you need to change your lug- nuts". I didn't believe him, but ordered the ones that have a shoulder that center the rim on the hub instead of the acorn bevel that most of us are used to. Vibration disappeared.

 

[GXFamily]

I had never had problems with acorn lug nuts on my GX, but bought my wife one and replaced stock with new wheels and tires and picked up a vibration. Chased it for weeks. Finally decided to get road force balancing (which can solve vibration issues on chunky off-road tires that even perfectly balanced centrifugal balancing can't fix) and the tech said "you need to change your lug- nuts". I didn't believe him, but ordered the ones that have a shoulder that center the rim on the hub instead of the acorn bevel that most of us are used to. Vibration disappeared.

I have gorilla ET lug nuts as I am running the SCS wheels.

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[Stonefoot72]

Yup, those are the good ones. That's all I've got that Red hasn't already detailed. Good luck

 

[Rednexus]

Spend 30 minutes pulling the front driveshaft and report back. I ran mine at highway speeds without it. It was honestly kind of fun to burn a bit of rubber in the GX as well .

For the CVs, it's probably not possible to drive with them pulled unless you cut the boots and pull the shaft and both sets of bearings out of the cups. Otherwise, you'd lose your front diff fluid and get crap in the inner wheel bearing too. It's totally doable to pull the shafts out and leave the inner/outer cups in the rig, but it would require re-booting the CVs when you are done.