Friends, I apologize in advance if this is covered somewhere else, but I used search and could not find anything describing exactly what I'm experiencing, so I thought I'd post.

I have a 2004 GX470, about 205K miles, it's been maintained well. Last summer (June, 2022) I did the air bag delete and used Eibach springs/shocks. Job went well and it's been driving fine for thousands of miles until last week. Not sure the two are related, but I included that for full disclosure.

Last week, when heading out of the neighborhood I got on the gas and the vehicle got "squirrely" on me, to use racing terms. It is a bone dry, well-paved residential street. After hours of research, I believe the official term for what I experienced is yaw. Since nobody was around and all the kids were in school, I tried it again and when I begin to accelerate -- or cease to accelerate -- I get this yaw motion (sometimes to left, sometimes to right) that makes me feel like I've hit a small patch of ice, but then the vehicle catches itself.

The steering may be a bit loose, but I would not say significantly. There are no out of the ordinary sounds and if just going 20 MPH straight down the road, it will proceed straight ahead with no noticeable yaw or roll or other irregular motion. I intentionally hit the one bump we have and I went right over it with no reaction from the vehicle.

I was almost out of gas so I risked going out to local gas station so my mechanic could test drive without running out of gas. Country road, so I took it easy...I hit about 35 MPH (on a straight line) and got the yaw again and despite the "excitement" I knew it was not right to really be on the open road at this point, but I was 1/4 mile away from the station, so I got my gas and headed home without the experience happening again.

Tires are old but are at 4/32nds so I don't think that is it. I crawled under in the garage and tugged on front and rear sway bars and end links, given I am only human and can't replicate the physics of a two-ton vehicle one handed while lying on my back, they seemed solid. I've gone to all four corners and given it a "bounce" but saw/heard nothing irregular. Also, tire pressure was 32 all around. And there are no VSC or other lights on the dash other than the TPMS sensor which has been on since 2018 when I bought it and the generic "maintenance" light -- not the check engine one -- the other generic one that says "MAINTENANCE <something>".

I saw a few posts on yaw sensors and zero point calibrations...seems easy enough, but what I haven't seen is someone describe my experience, say they've done the calibration(s) and then had the issue disappear.

Anyone else experience this before? My fear is going to my mechanic, who I do trust, and have him say it's tires, shocks, other and dropping $1,000 or more on work and have the problem not go away. And I don't want to drive 20 miles to the dealer since they are gangsters based on previous experience.

Would appreciate hearing about any similar experiences you may have had like this!

 

So you are accelerating in a straight line, or through a corner when the symptoms present themselves? If you can provide additional details on exactly what happens or doesn't happen when the symptoms occur, any dash lights or beeps from the truck, etc. that would be helpful.

 

Thanks.

Good ole' straight line acceleration, point A to point B. No lights on dash. No beeps. No clunks. Just yaw.

It feels like the first day of winter when you are driving and hit a small, unseen patch of ice on a road and you get a little rotation like a slide is going to start but it catches itself and straightens it up. I could not quantify it in degrees if "straight ahead" were 0 and my rear were 180, and it is not a violent yaw, but a little "squirrely".

Imagine a slower version of this:

 

Did you check the panhard rod, that connects the rear axle cross-ways to the frame? If the bushings have gone, that will introduce some lateral slop.

And of course, put it on a lift and check for worn control arms and steering tie-rods.


Chip H.

 

Oh man, I did not check the panhard and generally ignored bushings. Good answer! I will take a peek.

 

I would start by making sure that all of your suspension bolts are tight front and rear then check for play in. The other thing to note which is probably not the problem but plays a part is the panhard geometry gets messed up and the axle is shifted towards the passenger side when you lift it. This means that it doesn't move the same distance left and right when it goes up vs down now so your rear end "steers" more and can make the truck feel more squirrely especially on the highway and require more steering to stay straight. You need to bring it back to flat to properly correct the truck back to stock and fix the roll center back to above ground which is the most critical item for tracking straight down the highway. EIM keith is the original weld in fix or Dr KDSS now makes a bolt in fix. This video explains why adjustable panhard bars don't actually fix the issue.

 

Did you get an alignment after the suspension work?

 

So straight line acceleration on dry asphalt, and you get the sensation of sliding sideways? No beeps/clunks/VSC intervention/brakes applied suggesting it's electronic? That really just leaves bushings and the like that have stopped doing their jobs.

I'd get the truck up on jackstands and start shaking things/prying and try and find the source that way. Try shaking the front tires side to side, and top to bottom and check for play there. Use a big screwdriver/pry bar to push on bushings and see if they have play.

 

No, I did not. Since I worked on the read and it drove OK on the test drive and days after, I cheap'ed out and did not align.

 

Yes, all true. That is what drove me mad. I'd have loved to hear a weird sound or something.

Would love it if the bushings were the problem. Seems most affordable solution if that's it.

I will keep everyone posted!

 

there is a chance your full tire is not making contact with the road. Also an alignment shop should be able to find damaged or worn suspension components

 

That's a brilliant video. Thanks for posting!

Chip H.

 

I'm taking it in on Monday, soonest I can get in to my shop.

Will take another peak in the garage this weekend before I head out.

 

I thought about this one for a couple of days, but am still not sure how you mean that, "full tire not making contact"?

Sorry, I am only mechanical enough to be dangerous.

 

Well fellas, looks like I am out of "Club Lexus"...my mechanic just called and advised my frame is cracked. I feel like Luke Skywalker after Darth Vader took out Obi Wan Kenobi on the Death Star.

I've had her for 4.5 years (put 70k on her) and while there was some frame rust, it never looked like it was at risk. I'm a 2002 4Runner owner and well aware of the frame rust issues from the early 2000s on the Toyota/Lexus trucks/SUVs and have seen ALOT of bad frames, but I guess it's not how much rust there is, but where the rust is.

Thanks for all the advice you've given. Hopefully I can find another GX or LX, but with the market the way it is, not sure what we can find in our price range. If I find one, I'll make an introductory post for her, no doubt.