Question - My 2013 has 162k on it. At 150k, I put brand new OEM shocks and springs take-offs from a 2022 Black Line GX. The vehicle has had meticulous service at dealer since new with exception of one major service done at a Lexus shop.

At highway speeds, there is a pronounced sway that is unnerving. I had thought it was the K02s that I had on it, they were terrible after 30k miles so I got rid of them for more trail oriented rubber.

At 30 mph, if I hit the pedal, you can feel the rear sway a bit. At highway speed, it does it too but more pronounced. Drove my wife’s GX with 80k on it this weekend and hers drives like new, Hers has the Luxury ride air leveling suspension but is otherwise the same.

The 13 has a 1/2” level on the front but is otherwise stock. Underneath is very clean, only minor surface rust on some parts. Nothing gross or rotted. It has been garage kept since new and never in a harsh climate for very long.

After searching other threads, it seems like some have experienced this too. What I need to know is what it’ll take to fix it. New bushings for the different suspension pieces or new sway bars?? Not sure but want to fix it. Don’t drive it much as I bought a toy to drive and use that most days but really like driving the GX. Even with 162k on it, it runs perfect and drives like a new car except for this sway issue.

Any assistance is appreciated.

 

I'd crawl underneath and inspect all suspension and steering joints (bolted connections, rubber bushings, etc.). The panhard bar and control arms for sure.

 

I was gunna say, rear panhard bar would be the first thing I look at.

You say in your sig that its leveled. I assume that means you only lifted the front and left the back at stock height? That could be causing weird caster or toe issues as the front of the truck lifts and the rear squats while accelerating. Usually, as the front suspension droops, you lose caster which is what helps the truck track straight at speed.

 

For suspension, I had initially put a spacer on the front and rear but took them off and replaced with just the front at 1/2” to keep it flat. When I had the OEM take off shocks and springs, I went with the slightly lower look.

This swaying didn’t start till about 10k ago. Had thought it was the work K02s but apparently not. I had the original lift/level setup on it for more than 25k miles without an issue.

Will check out that panhead bar, don’t quite know what that is but will find out. Appreciate it.

 

The diagonal bar, in the rear, goes laterally from one side to the other. It locates the rear end and keeps it in place during lateral G's. Otherwise the rear end would flop left and right and make handling unstable.

 

You need to take the truck to a Baer Suspension shop - at 10 years age, bushings can get shrunken and hard or swollen and mushy. Ether situation could be happening. It might not even be too bad at any one spot, but when you start talking about 4-6 bushings, all could be a little bit compromised and unable to deal with whatever wierd sine wave that is causing this motion at highway speed.

You might not have the expertise to gauge how far gone your rubber stuff is.

My ancient Corvette was making a "whacking" sound when I'd drive over the mountable curb and gutter, and I found my swaybar endink had broken in half - it was made of PLASTIC, for God's sake (thanks, GM!), so I had to recon shocks, swaybars, and endlinks all around the vehicle. Spendy!

 

Thanks for the suggestion- I live in the middle of Appalachia now, probably not a shop like that within 250 miles. I’ll get it to either a Toyota specialist or 4x4 place and have the bushings looked at. It is only 10 years old and kept in a garage more than 90% of the time, it’d be really odd if there were a lot in need of replacement- these vehicles are so well made and w great components.

Will have checked out.

 

If it was RWD only it would be fairly easy to point towards the rear end only, but being that all corners have an influence it makes it tough. My GX470 did something similar, but it was much more pronounced on deceleration. Hammer the throttle, then let off and it would dive fairly hard to the right. I also noticed it going over larger depressions in the interstate or 65mph roads where the suspension had a chance to load/unload and it would kinda drift over a bit. This was at just shy of 200k miles in WI, and our climate is very tough on vehicles.

I replaced both front LCA with oem Lexus parts thinking that there were some bad bushings in the front, and that didn't fix it. So then I replaced the upper and lower links (2) upper, (2) Lower (they basically keep the solid rear axle parallel to the vehicle, and it the correct vertical orientation) and that did the trick. What was happening was the worn bushings would allow the rear axle to rotate on a horizontal axis, and what was happening was the rear axle was coming out of square and actually steering the vehicle if that makes sense.

The bummer was individual bushings weren't available, only the complete arms. I wasn't all that happy about replacing basically every bushing in my suspension, but figured that it was money well spent because 200k and 15 years is a pretty good run. It drove like new when I was all done.

 

Logically speaking, something is probably loose, be it a bolted connection, bushing, or structural component failure (crack). And the rear half of the vehicle is where such a loose condition would have the greatest effect on the condition you're describing. I'd at least get under there and start throwing some eyeballs on things. Even better, check each bolted connection, and joint w/ wrenches and pry bars. Another idea is to follow your own GX and watch the rear end for any movement after the driver "steps on it."

 

Outstanding advice - thanks. Not sure how this happened as it would be nearly impossible for this unless it was not reassembled correctly when the shocks/springs thatI had put on were done. The UPPER CONTROL ARM in the rear was missing the bolt that holds the upper control arm in place. What bolt / nut combo is that? It is about 3 1/3 long and likely a thick one. The control arm and bushings are still in place but the bolt and nut are not there. I just can’t find a website that has the parts list that shows bolts, just the bigger parts. On the first pic, it is 4. 3 and 2 that I need but need a part number for this.

 

Found it!! Now I just gotta gete it and put it in there. Not sure why it was so difficult to find but this is it.

 

Lexus parts diagrams are terrible. It always seems like they have 5th graders draw them. haha

 

Well, I’m glad you found this. I guarantee you that an unmounted suspension arm will make the vehicle handle in a very questionable way.

This will conclusively solve your problem - and it’s a damned shame that you can’t rely on the work of a mechanic to prevent you from having a potentially life-threatening problem on the road.

 

A great example of why suspension bolt tightness is included and should be checked in the maintenance routine,

 

also a great example of why you should do your own work as much as possible