2004 TRD 4WD Excessive Rocking on Highway???

Hi - I have a 2004 Xtracab 4WD TRD. Love the truck except that about 4 years ago I noticed that, at highway speeds, whenever I went over a bridge deck back onto the main highway pavement (or after going over a minor pothole) the truck would begin to pitch left/right and I would have to slow down to stop it. This happens when I'm going 65-70 mph. If I didn't slow down it seemed that the pitch would accelerate freaking me out (thinking rollover). I ended up taking it in to the guy who had been servicing it for years. He thought perhaps all new shocks and rear springs would help ... $1000 later didn't seem to help. Any ideas what could be causing this? Wonder if worn bushings need replacing, sway bar, etc. It's a bit scary.

 

Could be a million different things. I would make a list and start going through everything one by one. Suspension joints, bushings, suspension bolts are torqued, tire pressure etc...

 

I did a little more research on this and I think it may be related to "tramlining". I found some good posts on it here in this forum. The worse case of it for me was on I-70 in Utah where the ruts created by semi trucks were massive. Still plan to take it in to an alignment specialist here in town to look it over. Things wear out after 16 years I guess.

 

It sounds a lot like a broken sway bar link or broken sway bar. I have seen a sway bar cracked in the middle before, just not on a tacoma. The sway bar bushings being worn wouldn't have that much of an effect on it but if they are worn to the point where there is very little rubber left then maybe.

Also if the bushings in the control arms are shot it can cause some weird stuff that may not show up while the vehicle is in the air. Same with ball joints, those need to be checked with the vehicle on the ground.
-Place a jack under the lower control arm with the tire on, if that doesn't fit you can jack the front up, place a jack stand under the LCA as far outward as possible and lower the truck till the suspension stops moving.
-Jack it up until the tire is a few inches off the ground
-Do the normal sided to side/up and down checks like you normally would
-Finally use a long (36" long) pry bar under the tire so that you can pry up on the tire. With short gentle movements up and back down, have a buddy place their hand (you can sometimes feel it in the pry bar, but can't identify upper from lower without and extra hand) on the upper and lower ball joints and check for movement.

This process keeps the suspension loaded where the vehicle normally rides and sometimes when the suspension is unloaded it may not show up. There are some vehicles that can only be checked properly this way and is a fool proof way to ensure ball joint condition.

Hopefully that makes sense and it helps!

 

This is exactly my problem. A few years ago while off-roading in the Nevada mountains I heard a loud clunk. Couldn't see anything under the truck but when I returned to the interstate the truck would roll left to right quite a bit.

Turned out to be a broken sway bar link. I replaced it and cured the problem. Over the next 3 or 4 years I replaced it again along with a broken link on the other side. Problem solved.

Then about 2 years ago I noticed a very similar action - left-to-right roll. Checked the links - all okay. Installed ES cushions and torqued them to 15 foot-pounds and the problem was reduced but not by much. Can't figure this out. Just sayin'.

 

Hello again - this problem has reared it's ugly head again but I have a bit more info that may help ...

As part of recent cross country move, I loaded up some stuff to take in this truck. Load in the back would be maybe 200-300 lbs of stuff (plus the fiberglass topper which has been on all along). Driving along the interstate (65-70 mph) the exact same thing happened as before - that seemingly out-of-control sway when going over uneven road (left or right side of road has dip/bump). Need to slow down and sometimes even apply brake to stop it. When pickup is not loaded with anything (basically the past 4 years), I wouldn't notice this at all on similar road conditions. I'm beginning to think it has something to do with those soft, 3 leaf springs and stock shocks (these were replaced in 2016 with standard original versions so they are not that old). My theory is that, with a load in the back, once the rear end is pitched one direction by bumps on that side, it starts an oscillation of some sort. If the road has a bump or dip that is same on both sides of the vehicle, no problem. Any ideas? Sway bar and linkages are A-OK.

 

Did the sway go away after any repairs from the previous time? Also, does it feel like the sway originates from the rear or the front?

I'm wondering if a suspension mounting point may be weak, like leaf spring shackle mount or something. It could be worn bushings in the leaf springs and shackle as well/

 

Oscillations are controlled by the shock absorbers not the springs. But in any case, it’s hard for me to understand what’s wrong because I have never experienced anything remotely like what you are describing.

More info here:

https://en.wikipedia.org/wiki/Harmonic_oscillator