92ls Vibration Issues

[flanker271]

Like some other first generation LS400's, my 92LS have vibration problems when going at speed of 65-70 mph. It vibrates more at the rear. I went to a Toyota dealer to have this checked out. They come up with four issues:

1. Upper control arm is loose

2. front shocks is leaking

3. struts are bad

4. transmission mount is bad.

I just wanted to know which one of these issue is the primary cause of vibration? (assuming I have new tires). Fixing all of them will cost me a fortune....upper control arm bushing alone costs $1225.99 to fix.

Thanks

[90LS400Lexus]

Yes, the well-known LS400 vibrations. My 90 LS400 is setting in the shop as we speak due to a vibration that was/is driving me crazy. I was supposed to take it yesterday, but the mechanics said to bring it today, because they would not have time to check it Monday. I took it today (around 9:15am) and dropped it off, went back home, got the other car and went to work. They obviously did not get to it today, as it was still setting outside the garage when I passed by there on my way home from work- which I noticed also the rear window was 1/2 way down after a very heavy storm that rolled through only about an hour before (I hope it was rolled down after the storm). When I went by after they closed- it was inside the bay, with the door closed, so hopefully they will be able to find the problem tomorrow.

On my car- is is smooth until about 35-40, then it had a rumbling type vibration (without the rumble of that makes sense) and lasts up to about 60MPH, then it smooths out. It seems to vibrate the entire passenger cabin and I am nearly 100% it is not the tires. 99LSguy has offered a lot of helpful information concerning the driveshaft and I am thinking it is something with that. They are going to check that out first thing in the morning. My car did not seem to do it when it was above 80 degrees, but lately, it does it at all temperatures- even in the 90s. Also it has worsened to the point where it also sometimes does it even at 30MPH, but it is even more pronounced to the point to where it will make the rear view mirror "flutter". I hope to get mine fixed soon. Does yours seem to do it less at a certain temperature? I doubt that it is your struts causing it.

[jzz30]

that rumble going away at higher speeds is classic symptoms of bad trans mount. i went through it all. i changed all of the front suspension and motor mounts which made a big difference too but the thing that topped the cake off was the trans mount instanly you could feel the difference even on startup, and that rumble was gone.

oh and 1200bucks seems a bit too much to change upper arms. i know they cost like 2-300 bucks a piece but that is still way too much. i did mine in like 2 hours both sides.

[flanker271]

My vibration doesn't seem to be temperature dependent....I live in Tucson, Arizona and it is around 103 F here today. The vibration starts at 62 mph, to be exact, and stops at 80mph no matter what day of the year or what road condition I'm on. At 85 mph and above it is silky smooth. I once tried it up to 102 mph, and it seems that the faster it gets, the more smooth it is!

90LS400, does your steering wheel vibrate also? It seems like only my seats (front and rear) vibrates.

I'll have the transmission mount fixed.

Thanks for all the help! B)

[90LS400Lexus]

My vibration doesn't seem to be temperature dependent....I live in Tucson, Arizona and it is around 103 F here today.  The vibration starts at 62 mph, to be exact, and stops at 80mph no matter what day of the year or what road condition I'm on.  At 85 mph and above it is silky smooth.  I once tried it up to 102 mph, and it seems that the faster it gets, the more smooth it is! 

90LS400, does your steering wheel vibrate also?  It seems like only my seats (front and rear) vibrates.

I'll have the transmission mount fixed.

Thanks for all the help!  B)

Yes, my steering wheel also vibrates, but no more than any other part of the car. No certain part of the car seems to vibrate any worse than the other. It is just a vibration that seems to vibrate the entire car. I can feel it anywhere in the car that I touch. Seats, steering wheel, door panels, etc. Mine did it worse in the winter, when it was below 60 degrees and it stopped when it was above 60 degrees. The warmer it was, the less it would do it and this has went on (no vibrations in warm weather) since late March or early April, until recently. Even when it is in the 90s (like it has been this week, with dewpoints in the 70s (very muggy) it has started to do it again and now at times it has another little problem speed at about 30 MPH and this is a little more noticable to the point to where the rear view mirror will "flutter". The previous problem speed was about 35 MPH and it would start and last until about 60-65. @ 66+ MPH, it is smooth as silk, as well as 1 MPH-34 MPH. I just got it back from the shop today and here are their exact words "not to sound ignorant, but we do not know what is wrong and we cannot feel any vibrations". He said bring it back if it got worse, but not to worry for now. He said he checked the driveshaft and everything was fine and tight. Oh well. Speaking of transmission mounts- I do remember seeing my gear shifter moving back and forth a little bit while driving, which is something that I had not noticed before the vibrations. Perhaps it is my transmission mount? How much does it cost to have this replaced?

[jzz30]

the tranny mount is about 60 bucks. and is easy to replace dont need much more than a jack and normal tools and jack stands. its a matter of removing liike 8 bolts or something like that if done at a shop it they should charge you half an hour (if they do that) to an hour of labor fees.

[90LS400Lexus]

Flanker- I may have asked before on another post - I cannot remember- but did you get your vibration problem repaired? I took my car to the Lexus dealer and they said they tires are "cupped" because it was not re-aligned after new rear struts. I will wear my tires out more before I get new ones. These were $400 tires- ruined.

[flanker271]

yes, as you know, I changed my transmission mount 2 weeks ago at a Toyota dealer and now there is absolutely no vibration. The struts and alignment doesn't contribute to the vibration at all, from my experience.

You see, I have bad ball joints, bad struts, and leaking front shocks. But by simply changing the transmission mount, all vibrations are gone. The Toyota dealer also told me that I'm going to wear out my tires unevenly without changing the struts. This is an expensive repair so I'll just wait until my current tires are all beat up and then do a major overhaul with new struts, new tires, new shocks, etc.

Anyway, my car still leans slightly to the right, but there are no vibrations whatsoever.

I think the transmission mount really made a difference.