I've been dealing with this issue for the past two and a half years of owning this truck. In the process, I've learned so much about cars, which was nice. The novelty of driving an 'older' or 'classic' Toyota fades fast when you gotta avoid highways or risk your sanity on I-40 (its already bad enough with the trucks on the highway, I don't need my bowels shook loose). So, on the highway, the truck shakes between 65-80, then after 85 it develops a droning noise. I rarely take the truck up to this speed since the engine was designed in the late eighties when speed wasn't a priority--passing emissions was. On top of that, the 4Runner's closest real world counter part is a brick.

I've taken it two four different shops only to have them to "call me when YOU find the problem because we sure as hell didn't"

The only major problem with this truck was that it was hit 22 years ago on the passenger side, bending the frame. It was repaired, but as such, a couple of things are a bit out of line (passenger side fender comes to mind). But, with a true alignment, it shouldn't matter, right? I took it to a frame and an alignment shop and they weren't concerned about that, even with my rear axle being an 1/8th of an inch a further back on the passenger side.

In the past two years, here is what I have done to try to correct the problem:

* New tires, Destination LEs (bad tire for this truck)
* New ball joints
* New CV axles (needs replacing again, but more on that in a sec)
* New wheel bearings (all four wheels, including the rear axles)
* New rotors and pads (not directly related)
* New rear drums
* New rear u joints
* New rear driveshaft
* New steering box
* New pitman arm
* Removed rear diff to check for any major problems.
* Checked with rims/tires off another car.
* New rear axles (no rear axle tube, yet)
* New panhard bar bushings
* New transmission mount
* New engine mounts
* New t-case mount.
* New front diff mount/bushings
* New body bushings
* New tires AGAIN (Bridgestone Dueler Revo2s--really great tire)
* New passenger side hub and spindle (seal failed on the back--water got inside). New bearings and ball joints were installed on this side again.

I'm running out of rubber to replace. When I took it to the last shop, the only solution they could offer was that the CV axle on the passenger side had too much play and it was slinging itself around. I've driven it on the highway with the hub cap removed (the one that sits in place of a locking hub if you have ADD.)
Front driveshaft was solid according to them as well. The only other things I could think, besides the CV on that side being worn (but negligible), is potentially the idler arm has too much play to feel it in the steering wheel, or the brass bushings in the hubs are worn out, but once again that is negligible.

What else, you guys? I'm tired of this issue!

 

Holy ground up restoration Batman! I just commented on your other post regarding alignment and saw this, WOW.
Does the vibration change when you: touch the brakes, turn, accelerate/decelerate?
Do you feel it in the steering wheel (wiggles when you let go) or more in the seat of your pants?

 

You mentioned a warped brake rotor on your other post, let's continue here, you also mentioned driving around with the rear driveshaft removed with it still shaking and blocking up the rear looking for wobble, you should block up the front and check that, but that rotor could fix everything. your list above says new rotors, do you have a brake dragging? You can borrow my ass-ometer, depending on your location. If it's tropical and you are buying the tickets I'll be right there!!

 

Yeah! Its kinda nuts seeing all of it in one place. 15 years of neglect will do that to a truck. This is just suspension work. I've done a boatload of interior, exterior and engine work too. Besides the shaking, paint, smallish dents/scratches, and the damaged rear quarter panel (Still sick over that), the car is just about new again.
The shake doesn't change when I touch the brakes, but if I'm accelerating faster or decelerating faster, it feels more severe. I feel when I go over bumps it stops shaking WHILE i'm bumping around over the bump, but turning doesn't seem to affect it.

I'm almost wondering if I have a brake dragging or having a caliper piston seize on the passenger side. Right now the truck pulls to the drivers side when I stop lightly but then it evens out. BOTH rotors were replaced Dec. 2016. I'd felt a ton of fade the past few months, which seemed quick, but I'd put almost 8k miles on the truck in 2017, so I wasn't sure. I'd had a wheel bearing fail thanks to a bad seal and it seized so bad I had to get a new hub AND spindle. I replaced that rotor while it was off and 90% of the fade went away. Its basically non-existent.

I sure wish I could afford some plane tickets right now! $435 nets you a round trip from beautiful Anchorage, AK to crusty Memphis, TN haha.

 

I have a spare passenger side caliper I'll be swapping out this weekend, along with a new set of Bilstein 4600s (super, super excited).

Finally replacing the sway bar components and the driver side disc.

A dragging caliper makes a ton of sense though. With bigger tires, the shake got worse. After having a really good roadforce balance done, the shake lessens.

 

I have never had personal experience with a road force balancer, can you watch the tire tread and wheel while it is spinning on the balancer?
I have seen many vibration issues caused by slightly bent wheels and tire tread that wobbled side to side or up and down when the tire was spinning.
If you don't look for it you could replace a lot of things trying to get rid of vibrations. I do see where you said you tried different tire though.
Another vibration cause that I have run across in the past was "cold flat spots" this may have little or no effect in your area, but basically when your vehicle is parked (particularly in cold weather) the tires will get a flat spot. I was told Toyotas were very susceptible to this due to the light weight allowing it to have more effect and the relatively low tire pressures for the size of the tires.
The only remedy for this is to heat up the tires by driving 5-10 miles. the reason I mention this is because I worked at a Toyota dealer in Alaska and occasionally customers would drop their vehicles off the day before (or several before) we worked on them and if we balanced the tires before driving it they would be balanced with the flat spot in the tire and as soon as it was driven and the tires went back to round they were out of balance.
I am running out of constructive suggestions to troubleshoot your vibration, but if you can find a shop with really sophisticated tools for finding vibrations there are ways to measure the frequency of the noise and do the math to figure out if it is wheel/axle speed or driveline, or a particular transmission gear or engine rpm. They can also use "chassis ears" mounted at several points under your vehicle to determine where the noise/vibration is strongest.
Good luck!

 

The last shop I took it to mentioned one rim had trouble balancing and was maybe a bit bent (just from watching tread), but they didn't think it was severe enough to cause that shake/vibration. The road force I believe puts load on the tire so its like its on the car. It hasn't dropped below freezing here in a while but this has been going on for a while--even when I drove it across NM (hot).

That is my next step if the small things I have lined up don't fix it. That and find a specialized frame shop that might have a better idea as to the frame's alignment. It is definitely not engine, nor is it transmission. I can ride it downhill in neutral and the same shake happens at the same speed.

Thank you for your ideas!