95 Ls 400 Vibrates At 75 To 85

[1995 LS 400]

My 95 LS 400 used to vibrate around 80 mph and didn't have much deviation above or below it. Now, it seems to start sometimes below 75 and vibrates up to 85 or higher. On other times, though, it will run smoothly at 80.

I've tried a number of items in bushings, electrical, etc but still cannot find the source.

Any suggestions?

[Yamae]

I had a similar problem but the vibration was also noticeable when not running. I mean, I noticed the vibration at 2500rpm when parked and the gear position was P or N.

It was initially only at a spot rpm but as months passed it turned out to be 2500rpm ± 100rpm then to ± 200 rpm. I also felt that the engine was misfiring because the engine sounded a bit rough when revving between 2250rpm to 2750rpm.

I have checked several items but the conclusion was simply the worn transmission mount. After I replaced it, the vibration was disappeared as well as the car became quieter than before. The symptom I thought the misfiring was caused by the noise from the engine mount since the metal and the metal at the mount was barely touching because of the compressed and cracked rubber.

[landar]

Tires. Rotate them and recheck.

[Larry W]

Check your tires...rebalance them and rotate...should take care of the problem.