Humming Noise in 2007 TRD OffRoad

Hello everyone-

Thought I might crowdsource this problem prior to going to a mechanic.

I'm the original owner of a 2007 TRD OffRoad. I lifted it 2.5" in 2010 (running 33" tires). I recently added a 5/8" leveling kit to the front suspension, as well as a differential drop. I had to disconnect the upper control arms to install the leveling spacers.

Since adding the leveling kit and diff drop, I've noticed a humming sound, both at low and high speeds. The sound is relatively low in pitch at low speeds, increasing in pitch at higher rates of speed, and goes completely away when turning right at highway speeds (still present when turning left). I do have RCI aluminum skid plates installed; the diff drop brought the diff very close to the plates, but I don't think this is the cause, given the sound stops when turning right... or maybe I'm wrong.

There's no vibration associated with the sound, neither through the steering wheel or what I can feel through the body of the truck. 4WD still works perfectly. The truck has 95,000 miles on it.

Anyone have any ideas as to what the cause might be? I'd like to avoid any damage to the truck by continuing to use it as a daily driver.

Thanks!

 

If the noise only started after the spacer lift/level and diff drop, I would assume that is the cause. Or more specifically by altering those things you altered the CV angles enough that now they are causing other things to make noise (wheel bearings, drive axles, something else that we can't hear over the internet). Simple thing is to remove the spacer & drop but I'm gonna go on a limb and guess you don't want to do that. Harder thing is to make the other parts quiet now that you made modifications.

Lots more info in the Suspension sub-forum. Good luck and welcome to Tacoma World.

https://www.tacomaworld.com/forums/suspension.18/

 

Hey, thanks for the response. Ya, removing the hardware is an option, but I don't really want to do that, particularly with the diff drop.

I'm wondering if the problem might be alignment. I don't know.

Thanks again, particularly for the link to the suspension forum. Cheers.

 

So, took the diff drop off (weekend 1), trim packers off (weekend 2), rotated the tires (weekend 3)... still having the irritating noise. What a pain. Good news is that I'm now intimately familiar with the front suspension of the truck.

 

You mentioned the sound stops when you turn. I suspect bad wheel bearings. If you zig zag down the road and the sound comes and goes you're loading and unloading the wheel bearings.

 

Thank for the advice; this was exceptionally helpful.
Jacked the truck up this morning whilst everyone was sleeping, and front left hub fails the spin test. Off to grab a replacement. Thank you again.