Well, the dealer claims they can find no issue... even gave them Spirollis part numbers and diagnosis... They did discover (after I mentioned that I was hearing a noise when transitioning from roadways to entrance aprons (say at a gas station) ) that the "right rear high sensor supporter nut" was loose... Will see if if continues to happen...

 

You are absolutely right. Cycling thru does reset something and smoothes out the ride. Mine went back to factory smooth when I did this after the clunk fix. It was so bad after the fix that I was considering trading the truck because its ride went from being like a magic carpet to worse than my old Mazda mulch truck that I keep on hand. I discovered the cycling by mistake and it fixed the ride.

 

Hey all - brand new here. I have a new to me (May 2008) 2003 with 34,000 miles. Got it immediately into my local dealer to fix the clunk and had immediate ride issues. Speed bumps are a nightmare! I'm going to try the cycle fix as soon as I'm in the car later today.

Question is - since I'm out of warranty based on age of the vehicle - will they fix this problem (without major $$$ to me) because it seems to have been born out of the TSB repair?

Thanks!

 

Is it the effect of a new driveshaft design. Mine has been doing this as well. I jacked up the rear the other day and noticed that the shocks were oily in the middle where the two halves go into each other. I wonder if the clunk fix damaged the shocks?

 

My somewhat educated guess (I've done a ton of DIY suspension work) is that they skipped an important step when bolting things back together, and didn't have the suspension @ ride-height when they torqued down the "trailing arms".

If the mechanic torqued the bolts (and therefore the bushings) at full-droop, then you end up with two side effects:
1) harsher ride because the twisted bushing is acting as additional spring rate
2) far faster bushing wear.

What you want to do (and what I'm nearly certain the manual specifies) is: "finger tight" the bolts first, then lower the truck onto its wheels, then torque the bolts. This gets the bushings oriented correctly.

I've had my clunk TSB done, and I too saw a much firmer ride as a result. I improved it a bit by "lowering" the rear of the truck back down to the normal ride height, but it still isn't as creamy smooth as before the fix. FWIW, I lowered it by adjusting the rear height sensors. Lowering it too far will get you into the bump-stops, which will give you a rough ride as well.

 

so why is it intermittent if its the bushings that are binding? Besides, mine didn't have the control arms done. just the driveshaft. whats the torque on the arms supposed to be set at?

 

you're right, if it was the bushings then i wouldn't be intermittent.

another guess: your rear ride height is a hair too low. The up/down cycle will get it back to "calibrated", but it can occasionally be off, in which case you're bouncing off teh bump stops.

Easy to check this. Go under the rear and see how much space you have between the axle and the bumpstops on both sides. Drive into the garage when it's riding rough and check it out, then check it out after doing the height high/low reset.

Ride height is actually pretty easy to tweak once you figure out what to fiddle with.

 

I had the sensors replaced once and readjusted again afterwards thinking the height was off. The tech at the dealer said one was off a bit. There is a factory spec they go off of. My rear shocks are a little wet meaning they aren't working at factory specs. The height probably should be readjusted again but not to oem standards but rather be "eyeballed".

 

Man am I glad I found this forum! I just bought a CPO '07 GX470 with 44,700 miles on it and while I've not noticed the 'clunk' on this vehicle (I did observe them on other GX's that I test drove) I AM experiencing the VERY noticeable rear 'bottoming-out' sensation when going over speed-bumps.

I'll be calling the dealership right away on this one! Wish me luck.

 

Keep us posted. Please!

 

Will do. I'm out of town for a few days so I won't be able to do much until next week, but I'll advise once I have more info. Chris, did I read correctly that your GX had the same problem? If so, how was it resolved?

 

yes, same problem. no resolve. they claim nothing is wrong.

 

UPDATE

Went to Scottsdale Lexus today and discussed the rear 'bottoming-out' sensation. I have an appointment to bring the GX470 in on Monday morning at 8:00am so we can have a tech take a ride with me to determine what's causing it. The service advisor's quick-n'-dirty assessment was either the rear shocks need to be replaced or perhaps the height sensors need to be replaced.

Either way, he acknowledged it sounds like a real problem and is committed to correcting it. We'll see!

 

i jacked up the gx when changing out my wheels and noticed the rear shocks were moist at the joint where one half goes into the other. It has to be the shocks.

 

SECOND UPDATE

I dropped my 2007 GX470 off at Scottsdale Lexus this morning. My service advisor told me they've "seen this problem before" and while he's not sure if they'll need to replace the shocks, the height sensors or both, he's confident they'll correct the issue.

For now I'm driving the 2010 ES350 loaner (nice car, by the way) and they hope to get the work completed today, although it may take another day or so depending on what needs to be replaced.