I have a 2006 LS 430 w/ 95K miles and love it. The car drives smooth and straight on the highway. It's a great cruiser on long road trips, but on city streets there's a "rattle" and "creaking" sound coming from the left front of the vehicle. It happens only at low speeds (less than 30mph) when going over small road imperfections as well as larger things like speed bumps (much louder). Performance wise, it seems to handle city roads ok but seems a bit rough at times. What's odd is that these front end noises occur mainly in humid weather, which is most of the time in Central Texas. I take frequent trips to Colorado and never hear a thing. I'm assuming it must be a bushing(s) somewhere in the front suspension. I've recently replaced the lower control arm bushings (used oem - the replaceable "rear" bushing of the front lca), lower ball joints, KYB struts w/ mounts, outer tie rods, and sway bar bushings. After searching related posts on CL, I was beginning to think the culprit was the upper control arm.

My indy mechanic said the upper control arm looks ok but the smaller bushing on the lower control arm is shot so the only option would be to replace the entire control arm. He also said the recently replaced KYB strut on that side needs replacing as well (thanks KYB) and that both outer tie rounds need to be replaced again (I used beck arnley).

My questions: Since I already replaced the lower control arm bushing, what improvement might I expect by replacing the control arm? Also, can anyone think of anything else it might be that I missed?

 

I had some minor creaking on road imperfections and I figured it was the rubber stabilizer bar bushings, so I had all 4 replaced (2 on the front bar, 2 on the rear bar) and eliminated that squeaking.

I also had a squeak anytime the engine block was moved (e.g. on imperfect roads or if you grab the block and push it up and down). Lexus dealership determined it was a damaged/rusted O2 sensor heat shield, and they cut it out (non-replaceable part). I didn't think it would solve the problem, but it sure did.

 

I have similar issues. I replaced everything you did including the uppers. I had lexus align the car and they didn't tighten the lower control arm bolt enough and it started making the squeaking over bumps. I tightened it up and it fixed that but it still pops when turning at slow speeds. My car had a completely thrashed front suspension when I got it so I replaced almost everything but there is still a clunk over bumps and it can be harsh. Strangely, in contrast to yours, my car clunks most days but when it rains it soaks up the bumps beautifully. Anyways I have done some reading and I ordered engine mounts and will put them in as some people said this helped them. Something to consider. I am pretty confident my issue is now motor mounts since when I start the car it sometimes makes a clunk and gear shifting is harsh when I push it hard. To get a softer ride though I think I will have to bite the bullet and buy new lowers.

 

An update. Motor mounts replaced. Big clunks over bumps is gone. Engine power delivery feels more "direct" and ridiculously smooth idle now.
Ride still seems a bit rough so maybe lower control arms but no CLUNK.

 

Were all the suspension parts tightened at ride height? Which struts did you use?

 

when I first started replacing things I didn't until I read some more. I went back and tightened things with the weight on the control arms. This improved things about 30-40% I would say for harshness. I put the jackstands under the lca and push on the fenders but the suspension never really settles to ride height until I drive. I feel like tightening the bolts with the suspension fully settled on one of the flat lifts would help.

 

I'm thinking about replacing the motor mounts. Did you use OEM or aftermarket?

 

They are a PITA to replace. If you don’t want to be back to square one doing the job again in 6 - 9 months buy genuine Toyota parts.

 

Get OEM only for the engine mounts. I think they're almost $300 for both. Most people have bad experiences with aftermarket mounts on most cars in general

 

Another update. The weather warmed up a bit this week and the clunk is back. I got them to do an alignment so the lca must have been moved and tightened. weird timing I thought it was solved. I think maybe now the small bushing in the lca is shot. It's the only suspension item left I haven't changed. Maybe the cold weather shrunk the metal around it and was preventing movement. I am going to buy some cheap lca on rockauto and throw them in, if I see improvement I'll get OEM. If its not this then something big is moving around in the engine bay or maybe the subframe bushings are gone.

 

These cars don't have subframe bushings, but the bolts could be loose. It's part of routine maintenance to check the torque on them.

 

Have you replaced the upper control arms?

 

May i suggest the new name of the topic: "Which aftermarket part produces less noise?"?

 

THANKS for posting this solution! I had replaced lower control arms earlier, but an irritating squeak remained. Especially when it was raining or humid. I didn't even think of looking at the sway bar blocks. Those stupid rubber blocks must be drying out and squeaking when the sway bar moves.

 

I just installed new Lexus M Mounts, from Bell Lexus, in Texas. If you are not in a hurry, call Bell and find out when their next sale is. A 3/8 inch drive, 14MM Flex socket will come in handy. You should have the Oil Level Sensor Gasket ( 90430-27001) on hand. It is likely old, brittle and seeping. Four 10MM bolts and it's out. (with the mount removed) Might want the oil level sensor connector (90980-11235)on hand, in case you break it, assembling the mount (in place).

Get about 14" long piece of 2x6 (NOT 2x4) lumber to raise the engine, with nice contact on the oil pan. You might need to "RIP" the 2x6 to narrow it.

The left side must be removed from the aluminum mounting bracket. Then reassembled in place. Right side is easy!

OH, and you should have the car on a lift! In my youth I did all kinds of work on Jack Stands, that stinks!!