Dangerous Diagonal Bounce/Sway @ Highway Speeds (1 Viewer)

[Harp123]

Guys, I have looked around for a thread with the following issue, but I have not found the same problem that I am having. Of course I may have missed it. I have a fully stock 2013 with 117,000 miles. When I purchased the vehicle it had about 93,000 miles. I have noticed since purchase diagonal bounce from left rear to front right when loaded with 4-5 people and about 50-60 lbs of gear. This occurs when when hitting a hump or dip in the road at 60-80 mph. I drove the vehicle yesterday for the first time in a while (Wife's) and while traveling around 75 mph coming off an elevated overpass the 200 started bouncing violently as described. It was enough to scare me and I realized that something is definitely wrong. So traveling at around 35 I jerked the wheel to the left and right and sorta duplicated the same thing. The bounce is like a vehicle with worn shocks keep bouncing after a dip, but diagonal. None of my shocks appear to be leaking. Anyone had similar problems? Any advice would be appreciated. I would like to have some ideals before taking to Toyota because they don't work on very many Landcruisers around these parts.

 

[terdrocket]

Sounds like at least a bad rear shock. Maybe more than 1

 

[Whiskerz]

I also vote a shock. Maybe 2 diagonal have failed. Give them a quick look and see if they are leaking.

 

[chilibit]

At that mileage I would replace all shocks and see what happens.

 

[KLF]

At those miles, the factory shocks don't owe you anything, it's likely they are worn out. They don't have to be leaking to be no good.

 

[TeCKis300]

I echo the others that it's the shocks. Particularly the rear, but the fronts are likely worn too.

Why bad shocks manifest in lateral/diagonal bounce and sway is because of the solid rear axle architecture. It's located side to side by a link called a panhard bar, that centers the rear axle left to right under the vehicle. As the rear suspension aggressively cycles (as the shocks are worn and no longer adequately absorbing suspension energy), the rear axle actually does move left to right, because any link/bar follows a curve ("s" dimension in the lower graphic). Which manifests in your feeling the truck sway in a diagonal fashion.

 

[gaijin]

I wouldn't rule out a faulty KDSS system - at least worth a check at the dealer.

HTH

 

[highrisk]

I had an issue very similar to this and found the Pan hard had a little play in it. I tightened it down and it eliminated a noticible swaying motion from the truck.

I would also check the shocks and replace them if needed with that many miles. I hope this helps and good luck.

 

[arich]

I vote too much weight and you're hitting the bump stops AND you have a sloppy suspension. This was also the feeling I hated when I bought the truck new. Search my threads. I've changed the suspensions few times.

 

[Markuson]

OE shocks are...ahem...shockingly cheap.

A low-pain replacement item.

 

[Harp123]

Thanks for all the responses. I will start with the shocks and probably replace the rear coils and see where that takes me. I have been needing an excuse to install some air bags on my 200 as well. Thanks again.

 

[arich]

I might have airbags and a compressor if your interested. I bought them a while ago before changing rear springs

 

[isthatalexus]

Team,

I could not find a better place than this thread to post this question, please pardon if this is all wrong here.

Equipment: 2006 GX470, Nav + KDSS, babied mall crawler w/ 117k miles, about 2k miles on new OME 2" suspension (2886/90000 front, 2896/60004 rear)

Situation: first bigger off-road trip to Death Valley; moderate load; heavy washboard for extended time; some rock crawling trails.

Issue: after airing up, unlocking CD, and getting back on the road a very unsettling instability in the steering behavior became noticeable. The description @Harp123 offered above is about as close to the behavior I'm feeling as I've found. It feels fine going in a straight line, but corners and steering generally induces all kinds of yaw and roll, and breaking has much more pitch. I did have not tested for bounce with extreme steering inputs. Used to corner like a Miata.

Question: what could be the issue?

Hypothesis 1: spent so much time off-road that I don't remember the street behavior from before. (not super likely, but including for completeness)
Hypothesis 2: blew one or several of the brand new OME shocks (seems unlikely given OME reputation; no telltale signs of leaking from shocks)
Hypothesis 3: something with the steering (I'm mostly uneducated on this topic)
Hypothesis 4: something with the KDSS (no fluid visible in the usual locations)

Help me, h8mud-wan Kenobi. You're my only hope.

Thank you

 

[Cybermig]

I had a similar issue albeit nothing in my suspension is OE anymore. I would check the rear panhard and rear links (upper and lowers) and check if the bushings are worn which causes play and alignment issues under certain loads when driving. When driving at highway speeds sometimes it'd feel like the rear end would completely move sideways a couple inches which throws off the rear alignment considerably and changes the yaw of the truck.

My culprit was the upper rear links (again aftermarket Total Chaos w/ Urethane bushings but the OEs still can get worn) and replacing the bushings fixed the problem.

 

[Harp123]

I might have airbags and a compressor if your interested. I bought them a while ago before changing rear springs

I purchased 2 sets (Air Lift) two years ago and installed 1 set on my 100 series. I had intentions to install the other, but just kept putting it off. Thanks for the offer and if I can not find them now in all my junk_I may contact you.

 

[bloc]

Also try cycling your KDSS balance screws on a level surface.

If the system isn’t balanced it effectively tries to add lean to the truck and this can do odd things on the road.

I got my LC with 108k miles on it and the very first thing I did was swap the suspension with new OEM. No noticeable difference in ride quality. Either they are very well built, had been replaced recently, or the previous owner was very easy on my truck before I got it.

 

[isthatalexus]

I had a similar issue albeit nothing in my suspension is OE anymore. I would check the rear panhard and rear links (upper and lowers) and check if the bushings are worn which causes play and alignment issues under certain loads when driving. When driving at highway speeds sometimes it'd feel like the rear end would completely move sideways a couple inches which throws off the rear alignment considerably and changes the yaw of the truck.

My culprit was the upper rear links (again aftermarket Total Chaos w/ Urethane bushings but the OEs still can get worn) and replacing the bushings fixed the problem.

Right on. Thanks for the tip. Scheduling a crawl under the truck now.

 

[eXpLoreLX]

Resurrecting an old thread, just to repeat some of the above considerations and because this fixed my issue.

I found this thread by searching “LX570 sway” and of course came up with a couple of good options. This thread specifically called out the Panhard Rod with a nice little picture from @TeCKis300.

I took the advice here, and I scheduled a crawl under my truck. I found a considerably loose Panhard rod bolt. So if your truck is swaying, it’s worth the three minutes to crawl under your truck and look!

Retightening made a huge difference.