Gen 3 TRD OR Front Passenger Suspension Noice

Hey everyone,
First of all sorry for the spelling mistake in the post title. Spelling was never my strong suit
Also, I'm sorry to make another of these posts and I'm sure they are tiring. I have searched and read through similar posts but my symptoms seem a bit different than what I have seen in other posts.

I've been dealing with a persistent issue that's stumped 2 mechanics and friends alike. Here's the rundown: there's a clunking noise coming from the passenger front suspension. It happens when I hit sharp bumps at speed, drive over washboard roads, or while turning tightly left downhill (it does not happen when turning right). Strangely, it doesn't occur under normal driving conditions, swerving on flat roads to get body roll, or when shaking the vehicle while stationary.

I've tried everything from self-diagnosis to getting input from two shops. The first thought it might be the sway bar end links, which I replaced without solving the issue. The second suggested that my springs might be catching on the upper housing during compression. I applied silicone, but the noise persists. Both driver and passenger show these wear marks, so I do not think this is the cause. I can't reproduce the sound when the vehicle is stationary no matter how hard I shake or try and hit parts with a rubber mallet.

This problem has persisted for about three years, and while it hasn't worsened, it's become quite frustrating. 2019 TRD OR if that matters. The truck is equipped with Fox Performance 2.0 Coilovers, that were installed by the previous owner.

Photos and Vid for examples
Any ideas or suggestions would be greatly appreciated.

Video:
You can hear the sound happening when turning left, and it will stop when I'm turning right.
https://youtube.com/shorts/hGLUrmo8aBY?si=25RwYmxYdwcX9-qt


Passenger: (you can see some silicone I sprayed on the upper housing and above-mentioned wear marks on the spring surface just below the foxes tail)


Driver:

 

The fact that it only happens when turning one direction and not the other is making me think it's a control arm thing. If one side of a control arm is loose (either from bolts not tightened or a bad bushing) you would hear it only when putting force on it in that direction. Check both the LCA and UCA including the rubber bushings. Sometimes the lower cam bolts might feel tight but they actually aren't. This also kinda sounds like it could be a ball joint.

One other strange thing I noticed is that you have significantly more threads showing on the top hat bolts on the passenger side compared to the driver side. Unless you have a spacer on the driver side, that seems odd.

 

Thank you for your response. Are there any specific tests I can perform to check for loose parts when the truck is jacked up? I've tried using a rubber mallet on various components and kicking the tire while it's suspended off the ground to replicate the noise, but haven't been successful.

Also, it's interesting to note your observation with the top hat bolts; I hadn't noticed that before. As mentioned earlier, the previous owner handled the suspension work. Should this be a cause for concern? Would it be advisable to consider replacement?

 

@GreekGod did you take the wheel off and shake the UCA? What size wheels, tires and backspace? Any chance they are rubbing on the UCA or LCA?

Maybe the radiator mount or even sway arm mount?

It looks like there might be a 1/4” spacer on the drivers side. Maybe they added it to correct the taco lean instead of adjusting the preload.

 

Looks to me like there is a spacer. You can see it in the pictures, looks like 1/4 plate. Common to fix the taco lean.

The lower control arm bushings or lower shock bushing are what is sound like to me. There is an issue with the front body mounts under the radiator, they look fine but the metal sleeve inside wears through the rubber and rubs on the mount on the frame causing a metal on metal noise. It sounds like suspension to me but something else to check.

 

Unfortunately it's not the easiest thing to test by hand. You would need to unbolt the lower ball joint bracket from the hub so that the LCA is free to move on its own. Then try giving it a good yank forward and back and see what you can see/hear. Same with the UCA, but you can just pop the ball joint out of the spindle on that. Basically you are fighting against those rubber bushings, so giving them a wack with hammer won't do much. You need to force them in one direction hard enough to see if the rubber has failed and if you're getting metal to metal contact.

If you can rig up a camera (like a gopro) inside the wheel well pointed at the control arm bushings, that would probably be the best way to see what might be happening. If they are making that metal to metal noise, you should be able to see them moving around move than you would expect as you drive.

The LCA cam bolts like to corrode and seize on these trucks. So they can be tricky to test. If you check either bolt it might feel tight but can actually just be rusted solid while the whole cam adjuster assembly is still a bit loose. You need to try to actually remove the bolt to know if it's seized or not. Just mark the cam adjusters position first so you don't have to get it re-aligned.

The top hat bolts aren't really a concern. It's just that they are usually the exact same length, and the shock mount is the same thickness on both sides. So anything other than the same threads showing on both would indicate that there is something else between the top hat and the shock mount. Which is likely just a spacer for taco lean on the drivers side, but that's still a bit odd since the shocks have preload adjustment so the spacer isn't necessary in this case. Sometimes those top hat spacers can move around and make noise (even when tightened down, i've had it happen). But you said the noise was coming from the passenger side though so that's likely not the issue.

 

Could be your lower coilover spherical bearings. I had kings that started making clunking / squeaks and that was the issue. Ordered some new bearings and misalignment spacers, and my problem was solved. That or the body mounts, lower control arm bushings, or links

 

Firstly, I want to express my gratitude for everyone's responses; they have been enlightening and set me on the right path. Over the past week, I've continued to investigate the issue and expand my understanding. As a newcomer to the world of Tacos, I've delved deep into IFS to educate myself on its workings—it's always beneficial to learn, especially in troubleshooting situations.

I'd like to thank @Saskabush for the GoPro suggestion. I borrowed one from a friend and shot three videos (below) in an attempt to diagnose the issue.

Wheels: TRD 17" 4runner
Tires: BFG KO2 265/70 R17

Here's what I've done so far:
- Confirmed that the wheels are securely fastened.
- Consulted with technicians at two local shops who listened to the sound while driving and inspected the vehicle on lifts. Despite their suggestions and replacing potentially problematic components, the issue persists.
- Ensured the skid plate is tightly secured.
- Removed the wheel and checked for play in the UCA, LCA, wheel hub, and sway bar—no looseness detected.
- Tested by shaking the truck vigorously with friends, compressing the suspension to its bump stops without reproducing the noise.

Observations:
- No steering looseness or play; all responses are firm and precise.
- The noise originates from the passenger side dashboard or floorboard area, with no accompanying vibration felt inside the cabin.
- Notably, the noise occurs more frequently when driving downhill and turning right, even on smooth roads. On bumps, it's specifically noticeable on hard impacts to the passenger wheel.

Analysis of the videos:
- Surprisingly, the noise isn't audible in any of the videos, despite confirming its occurrence as frequently as in the original recording from inside the cab.
- There's no significant visible movement in the videos, aside from perhaps some engine movement in video #2, although I'm uncertain about the typical amount of engine movement.

https://youtu.be/Osp-FZWqsA8?si=E-4a3hAMlAyKg57v
https://youtu.be/qV_s3EH_1ps?si=arps8UKTMEd05Q5f
https://youtube.com/shorts/HqVWgQldN5I?si=bBcziQjodPW9SwSm

I hope all my descriptions make sense and again want to thank everyone for their help.