Voran

Thanks for all of your suggestions. We've pretty much ruled out tires and wheels and are left with suspension (although at 24K and around a year old with 90% highway miles this shouldn't be an issue). The senior mechanic thought it might be a drive shaft that was out of balance and another independent mechanic had seen similar symptoms in a BMW with u-joint wear. Shocks seem to be fine in that the bounce test is negative. Did some fun manuevering rally-type driving in a parking lot around some cones and response at speeds up to 50 mph around corners was as superb as I remember. I'm still angry about the refusal to do anything about it by the service dealer. No offer to refer to another facility nor suggestions on how to diagnose the problems. Have spent about $1,100 on new sets of tires, several rebalances and alignments without even getting close to resolving the problem. Will try another dealer.

Need some help and advice. I own a 2006 Lexus IS350 that I bought new last year in October and have put over 24K miles in 8 months. At about 16K I noticed a slight oscillating vibration (1-1.5 seconds of high frequency followed by 0.5 seconds of no vibration). Mentioned this to the Lexus service and they noted unusual wear and cupping on the tires. Short story, have had the car aligned, replaced and balanced all 4 tires (replaced them with the new Eagle F1's) without solving the problem. Over the last month it's gotten worse. The vibration/shuddering is first noticeable around 70 mph, but only faintly on very smooth roads. It get's more noticeable at higher speeds. At 80 mph it's annoying and that's about where most of us in the Midwest set our cruise controls on I-29 where I spend about an hour each day. Have taken it in to the Lexus dealer (Superior Lexus of Kansas City) 3 times. Two times a senior mechanic road in the car and verified what I was feeling. He even suggested it might be a drive shaft that was out of balance. However, and this is where it gets really annoying, the service manager called and said she would refuse to fix the problem since in order to duplicate and diagnose it her mechanics would have to drive faster than the posted speed limit. So I'm stuck in a catch 22. They'd like to fix it but can't since they won't allow their mechanics to diagnose it. I think it's a safety issue and am left with a number of alternatives. Take it to an independent mechanic and pay for the diagnosis and services myself; dump the car (which otherwise I love) and buy a car that is designed for highway speeds; travel to other Lexus dealers to see if they will diagnose and fix it; drive it until something major happens (it is getting worse). Or, and this is option I'm least in favor of, seek legal remedy. Anybody out there in Lexus land have a similar problem or have solutions that'll be palatable?

Am looking for potential causes of a 2 second cyclical vibration that's most noticeable at highway speeds of 75 - 85 mph that began around 16K (car now has 23.5K) on my 2006 IS350 that was purchased new in October of 2007. Had the tires balanced and alignment checked to no avail. Took the Lexus senior mechanic on a ride to confirm the vibrations and he said I needed new tires since the old ones had some alignment wear and cupping. Last week I replaced all 4 of them with the new GY Eagle F1's and still have the vibration. Have scheduled a visit next week for them to take another look at the problem. The vibrations are barely perceptible at 70 mph but become irritatingly noticeable at 75 - 85 mph but don't seem to get any worse at much higher speeds. Have had it has high as 135 to and they almost seem to go away at around 110. They do seem to be related to speed but not linearly since the cycle seems to be about the same 2 seconds or marginally less at above 100 than at 75. Anybody know of a TSB on this issue? Have similar problems? Got any ideas?

2006 IS 350 , 1, $43K Superior Lexus, current mileage 23,700 Since 10/2007 usual maintenance except $1,100 for new Goodyear F1 tires All maintenance done at Superior Lexus in Kansas City Last maintenance $20K routine and to check alignment on advanced wearing of tires. No modifications. If desired your age and insurance you pay. Problems Have noticed an oscillating vibration that's quite noticeable at highway speeds ~ 75 - 85 mph that began insidiously at around 16K. This is especially noticeable on smooth roads. The cycles last about 2 seconds with 1 second of vibrations that could easily be assumed to be a tire out of balance but then dissipate for about a second then return. Have replaced all 4 tires with the new Goodyear Eagle F1's without resolving the problem. Am wondering what else could be causing this. Have taken the car into the dealership and took a mechanic for a test ride who confirmed the vibration and said it was the tires. But now that the tires are replaced and alignment checked the vibraton is still present. Have an appointment next week to have them take another look at the car. Am wondering whether there are any TSB's on this type of problem.