On my '05 GS430, I have this problem where the alignment seems to change dramatically anytime I hit even a small bump in the road or pothole. I've had the car for about a year now and within a month of driving it, I drove over a manhole cover and immediately afterwards my steering wheel was about 45* off center. Took it to a shop and got it aligned, the FR wheel had a bunch of toe out, which was corrected. About 2 months later, I hit another small pothole and the alignment was off again. Same wheel. This time with toe out. Frustrated since I just paid for an alignment which is now ruined, I got some wrenches and adjusted the FR toe arm until the wheel was straight again and the steering wheel was centered.

Now about 6 months later, I hit another bump in the road (PA roads are a nightmare), not even a pothole, just a poorly covered up construction job, and within a mile my steering wheel started to drift off center. I pulled over and checked the wheel, and sure enough, the FR wheel has an extreme amount of toe in. The FR wheel was at least 45* inward. I was only a half mile from home so I continued driving slowly, and the alignment got more and more off center the further I drove. Then this loud, constant, "beep beep beep beep" started coming from my dash. I limped the car slowly home and parked it.

Any idea what would cause the toe to be changed so dramatically like this, or why it got worse over time? When I got back I turned each wheel out and shook the control arms and nothing felt loose. Last time the car was up on stands I checked everything and it all looked good. The tie rod locking nuts are all tight too. Could use some tips for troubleshooting this so I can purchase the right replacement parts, because after what happened today I'm sure something is really wrong.
The previous owner put BC coils on and had a shop change the ball joints at the same time, so I wouldn't think those are the problem.

 

Check all other suspension parts around. You may have loose upper - lower control arms, ball joints, inner - outer tie rods, etc.
I can imagine that some wheel alignment stations don't check the integrity / firmness of the suspension system before adjusting.

There are no suspension parts that can cause "beep-beep-beep" from the dashboard.
This buzzer is usually connected to some critical alarms related to the brake system, low engine oil pressure, high coolant temperature, etc.
Are your ABS / VSC lights on?

 

Now that you mention it, yeah I'm pretty sure the beeping was from the VSC. The alignment must be so bad that it thinks the wheel is slipping. I'm going to jack it up tomorrow and check all the suspensions components. I've given them all a good shake before and nothing seemed loose, so if you have any tips for troubleshooting those parts other than shaking them let me know.

 

You've mentioned readjusting the steering rod ends, but are they loose after the symptoms start? Have you noted their position immediately after alignment and again after the issue? If they aren't coming loose, then you should be looking inboard at the inner steering rod or the rack itself.
Follow-up question:
Was your steering wheel off-center when the unaffected wheel was straight ahead, or while compensating for the pull of the toed wheel?

 

Both tie rod nuts were tight after. I'm going to mark them with a paint pen to be sure that they aren't moving. Could be the rack. With the front left wheel straight ahead the steering wheel is always centered. If I straighten the problem wheel (front right) the steering wheel is at the 2 o clock position. I pulled the toe out and now the wheels are straight and the steering wheel is back to center. Now that I type this out it seems like it must be the tie rod.

 

It’s more than likely the tie rods, especially the inner. It’s very hard to tell if they’re bad unless you completely disconnect the inner tie rods which mechanics aren’t doing when they do alignment. I would change both inner and outer tie rods. Mechanics always told me they’re fine but they end up being worn once you remove them. If the rear toe isn’t holding it’s mostly the toe arms or in my case it was also the lip that the alignment cam rests against being worn and flat causing the cam to shift over bumps.

 

I jacked it up and noticed that if I put both hands on the wheel when its in the air, and push on either the left or right side, there is a little bit of play before the wheel moves (as if I were turning the steering wheel). If I push back and forth it wiggles a bit before moving. Is this another sign that it's the tie rods? Or is this a wheel bearing issue. It only does it when applying force in or out on the horizontal plane if that makes sense. Not if I push on the top and bottom.

 

yes that’s definitely a symptom of bad tie rods. Could also be lower control arms but your symptoms all point to bad tie rods. Especially the fact your alignment changes over bumps. Only tie rods can do that really

 

And to take the wheel bearings out of the equation, have someone press hard on the brake pedal as you wiggle the wheel.

 

Thanks for the advice everyone. I've ordered 2 sets of inner and outer tie rods for now and will replace both sides.