What's funny is that I have an unrelated thread going where someone just responded with the exact opposite of what you said. His opinion was to go to independents as much as you can to save money because these cars aren't that hard to work on.

I'm no mechanic so its all complicated to me. I would imagine that if something was complex for my mechanic he would either say he can't do it or charge me extra. I also try to be a gatekeeper and do my best to filter the things a Lexus dealer should do from the "simpler" stuff my mechanic can handle. For example I had my mechanic replace my control arms.

 

Lots of independent shops specialize in specialty or marquee brands. For example, a local shop here will only work on German cars....BMW MB etc. Yet another only on VW. There's niche markets like that. Heck, I work on my Lex all the time and I'm no mechanic. It's easier than my BMW was.

Anyone who thinks the LS is complicated or involves witchcraft to repair, has never owned a BMW! LOL. At the end of the day, the drivetrain is very similar to a Tundra or Camry and many parts are shared between them. Honestly, my LS is one of the easiest cars I've ever worked on....and I've owned plenty of cars and trucks..

 

Yes, my car has been fine since I got the new tires. Make sure you have the new tires road force balanced. Road force balance is much more involved than a standard balance. There was some mention that the reading had to be less than "10" per the Lexus specs. Even with new Michelins, it took a couple of days to RF balance to the specification.

 

As an update, I purchased and installed four new Michelin Primacy MXM4 tires. While I immediately noticed the new tires provided a quieter ride, the vibrating noise did not go away. This is a huge bummer since I expected the new tires to solve the problem based on research done on Club Lexus. So now I'm at a loss.

Could it be the axle? Lexus says yes but my independent mechanic says no.

Also, does anyone think a road force balancing on my new tires would make a difference? I had a RF balance done on the original Turanzas and that didn't solve the problem. I doubt they would be the difference maker with my new Michelins. Once again, I'm at a loss on what my next step should be.

Thanks.

 

Very unlikely to be an axle if you have an audible noise in the 55-65 mph range. Axles rotate at wheel speed, giving a vibration at only about 9 cycles per second at 60 mph. Human hearing range starts at 15-20 cycles per second. However, the rear drive shaft, front driveshaft and transfer case output components all rotate at about 34 times per second at 60 mph. That will make a nice low base noise that may or may not oscillate in intensity.

To get an audible vibration from an imbalanced tire, say a minimum of 20 cycles per second, would require at least 130 mph.

Your next step is a tough one, finding someplace with a tech who understands this stuff and can take the diagnostic time to find the cause.

One question. Does the sound/vibration change if you are accelerating or coasting? Driveline vibes often change depending on power on or coasting. Wheel, tire and wheel bearing problems tend to be road speed dependent and not change with power loading or coasting.

 

Great post! I had never before considered link between RPM of components (converted to rev/sec) and frequency (Hz) of vibration noise produced. Thanks for the insight.

 

Thanks. I was trying to avoid technical terms here. Stuff like Hz makes most folks eyes glaze over. In my 34 years in the tire and service bizz, I test drove thousands of cars and light trucks for vibrations, noises, alignment, handling and performance/driveability concerns. I so often wish I could just drive these problem cars so often posted about on this and other forums. Without actually experiencing the problem it's hard to give useful advice.

Most techs hate to fool with vibration and noise complaints. They can be a black hole for unpaid daig time. Plus, anything beyond tire balancing can get expensive real fast so service writers and customers tend to fixate on tires and balance too much. Balance is only a part of the diag. tree. Try telling a customer who came in for a $30 tire balance that they need a new two piece driveshaft on an out of warranty Lexus.

 

Thanks Robert1408. To answer your question no the vibration and sound do NOT change between accelerating and coasting. Upon another member's recommendation I even put the car in Neutral while at 60mph. The sound/vibration did not change when I put it in Neutral.

I assume that means I can safely eliminate the driveshaft and transfer case as potential causes, correct? Could it be the bearings? The wheels are OEM.

 

The sound not changing between coasting and acceleration makes it less likely but does not eliminate a driveline source. At the same time it does make it more likely to be a bearing problem. A good way to determine a bearing sound is to listen while steering left and right on a wide, smooth road. A bad hub bearing will usually get louder or quieter depending on cornering (side loading).

Again, the sound frequency will often be telling in these cases. Driveshafts on an LS will make a low, rumbling sound at about 33-34 cycles/sec at 60 mph. A hub bearing will make a higher pitched sound of maybe 300-2,000 cycles, depending on the failure mode. I sure hope this is any help and you can get this fixed. It would drive me to distraction!

 

Thanks for your help. This is driving me nuts. I bought this car for ride comfort. There's nothing comforting about sound and vibration coming from the floorboard. I found an old CL thread that sounds like others experienced something similar to my problem. Thing that scares me is no one figured it out after extensive investigation. Maybe I'll get lucky and crack the code.

Your help and advice is much appreciated.

 

Robert1408, after doing more digging I found the following TSIB (http://www.lambros.net/LexusTechInfo...SB-0147-08.pdf) which is related to symptoms of vibration between 55mph-65mph. On paper this seems like precisely my problem but this TSIB says the repair procedure calls for re-indexing the drive shaft and installing a brace/bumpers in the REAR suspension. My car produces vibrations that I feel in FRONT floorboards on both driver and passenger sides. Also, I had confirmed my vibration/sound does not change whether I'm coasting, accelerating or even in neutral while moving at 55mph-65mph. As you stated this significantly reduced the likelihood it was driveline-related.

Do you think this TSIB could apply to me given your experiences and the info I've shared? Thanks.

PS
I really want to believe I found the solution. Stabbing in the dark sucks.

 

Well, the way I read this TSIB is that it applies to rwd models. Even so, the TSIB directs the tech to the service manuals' driveline section for detailed procedures and special tools and gauges to measure and set driveshaft angles as an integral part of this TSIB. The roof brace it talks about is 10 hours warranty labor! I'd say this TSIB would be way down the list of things to do here. Unfortunately, my alldatadiy subscription only covers rwd, not awd so I don't know how the rear driveshaft is set up on your car. Or the front one either.

Since I can't drive the car and don't know the vibration/noise frequency, or the amplitude and relative intensity, it's only possible to give you some ideas. BTW, did you get to try steering the car left and right while the noise was happening to see if it changed? If it didn't change, then I'm leaning towards this being a driveline problem.

If it's driveline, throwing parts at it will be very expensive. It's highly unlikely a visual inspection will reveal anything obvious. Indexing the rear shaft at the diff doesn't look too hard to do and would be worth a try. Checking the trans mount isn't too hard and one that has settled or is loose will make all kinds of problems. Beyond that, it gets much harder. Proper inspection just for driveshaft run-out requires its removal. Put one of these cars on a lift and have a good look under there. Now imagine removing either driveshaft. Step one: remove entire exhaust system….and so on.

If we assume this is a driveline problem (not a certainty), in my experience complete replacement of the rear drive shaft assembly is the most likely fix. Even a new shaft should be checked for run-out. Again, I advise a skilled diagnosis. Parts and procedures are just too expensive for much guessing. Sorry to be a wet towel here but if you get this fixed, shout it from the rooftops and let us know!

 

Thanks. I did try to test for a bad bearing as you recommended. It's hard to do much of a turn at 60 mph but I tried by changing lanes harshly. After several lane changes, I did not notice any change in the vibration/sound. Good thought. I think I'll bring the TSIB to Lexus and use it to start a discussion about what to check next. The first time I had them look at it they said it was a combo of the tires and the axle. I got new tires and no change so hopefully they'll put more thought into it.

Thanks again. If I ever figure this out I will definitely share my findings.

 

I finally solved this problem. I ended up taking my car to a different Lexus dealership in my area and they spent a few days looking into it. The end solution was replacing the front hub bearing assemblies and also straightening 3 bent wheels. Now there is absolutely no noise or vibration.

The hub bearing replacement cost about $1400 but I got that covered by a third party warranty I had purchased last month (woo hoo!). I decided to have my OEM wheels straightened and refinished instead of buying new wheels. The wheel work cost $500 for all four wheels.

Thanks to everyone on this thread who chimed in with their advice.