priestsls4

my new (HA!) 91 with 200k+ is running and driving great except one problem that has recently crept up...

when I took a cruise on the highway this weekend and got her up to speed she started to shake. it seems to be emanating from the front and possibly passenger side. the steering wheel shakes and the shifter shakes.

when I slow down, it decreases in intensity and usually goes away. I can then get back to cruising speed and she drives fine. it then mysteriously reappears from time to time. for example, it has not done it either of the last two days.

does this sound suspension related? could it be motor and/or transmition mounts (since this is a typical problem)? let me know what you all think!

billydpowe

iTrader: (1)

one of my 99's gets a light shake/shimmy at 75 increases at 80 and easies up at 85. It is not bad, but I KNOW it should not be there.. my other 99 is rock solid at all speeds. I also had this problem with a 97 too. hard to figure

I have replaced the engine mounts and strut rod bushings.. rotors and pads, no change.

my left rear tire had a knot on it, causing the problem.

RA40

iTrader: (6)

Any indications of uneven tire wear?

priestsls4

Tires are fairly new and look good...

vinnie420

iTrader: (1)

Mine does this same exact thing, usually when the tranny is cold otr i let it just sit and run to warm up. It feels like a loose wheel. All I did was have a good look at anything that would cause a vibration like this and everything on my ride seemed ok. I asked one of the techs where I work and when I told him the symptoms without hesitation he said my trans case is warped. I guess it's a common problem with these cars. But if I were you I would look the car over real good and make sure there is nothing loose in the suspension and check the condition of the mounts. If all that stuff checks out you may have the same problem that I do.

gtoden1

How about front end aliment?

JimsGX

First I've heard of this problem... Do you trust this guy? What kind of mechanic is he?

PureDrifter

iTrader: (10)

trans case warped? what is he on and can i get some?

priestsls4

all suspension connections seem solid and many of the prone parts have been replaced. I will go back through the records again to see what hasnt been addressed and put it on the rack do some whackin and tuggin...

the alignment question made me think for a minute....the alignment seems great; however, when the thing starts to shake it definitely has a pull to the right...

Im with you guys that a warped tc seems, well, warped...but I have found in my varied vehicle experiences that issues vary from car to car and I have heard of stranger things...

seems to me that as prone these are to having transmission mounts fail that the corresponding movement would lead to more realistic problems more so than warping...

anyway, this is exactly why I am here...I am a member of a site for each of my vehicles and the resulting knowledge has been invaluable...I have saved tens of thousands of dollars thanks to the knowledge base....Thanks everyone and keep the input coming!

bornpeace

check ur tire balance as well, i had the same problem at around 65 to 75. My front tire were out of round because of alignment. i did alignment and put my balanced rear tire infront.

vinnie420

iTrader: (1)

I trust this mechanic, he is the only one who works on my cars. He has been a Lexus tech since 91. He is an A tech and definitely our most experienced guy. I trust him enough that I drive this thing over 100mph at least once a day. I think this may have been one of those problems that were swept under the rug by Lexus. I thought he was crazy at first too. But there is nothing loose on the suspension of the car, if it was something like an unbalanced wheel or driveshaft the vibration would be constant. I get a wobble or vibration through the car from time to time, it ranges from slight to undrivable and goes away once the trans is up to temp. You can also feel it coming from the center of the car. I'm not saying this is the problem with priestsls4's car, but barring everything else checks out this could be the issue. I will be able to tell you for certain after I rip out this slushbox in favor of something with 5 or 6 forward gears and that requires a third pedal, but that's going to be some time down the road.

deanshark

Check the tire pressure. You say it happens on the highway. When the tires get hot the pressure goes up. Sometimes it doesn't go back down. I had this happen on another car (Grand Prix). The pressure went up to 60 psi and it felt like it was out of balance and it also pulled to the right. It was the right front. Also check the sidewalls of the tires (inside and outside) to see if you have any bubbles. It could just be a bad tire, you did say they are fairly new.

priestsls4

should have the balance and pressure question addressed by mid week. I just wanted to note that there does not appear to be any temperature issues. It doesnt do it or not do it based upon how cool or warm she is. In fact, I have only had it occur once when it was cool (the opposite of vinnie).

I do believe that it does have a speed connection as billy mentioned. It really doesnt happen unless I get her up and push her. now, it doesnt always do it and when it does, it will not just go away and come back at a certain speed. If I push her up to 70+ and she is fine...then it gradually starts to shake...I slow down and it will continue to shake down to near 40mph...though it never starts shaking at low speeds...

I suspect that what I have is harmonic in nature...when conditions are right (wrong) she gets in that zone and starts to shake...then you change the conditions and it goes away...hence I think it may be a combination of factors...a worn bushing...crushed mounts...tire out of balance...etc. I am going to comb through her this week....

Any suggestions on ordering the motor and tranny mounts?

dashan

Check for a partly stuck caliper and bad rotors (brakes). This is the problem that caused the 70 mph vibration in our car (not ls400).
We did the following (before realizing it was the caliper) but did not fix the vibration problem.
1. change two axles by a shop (we didn't pay the labor since problem not solved)
2. tire balance by Firestone.
3. rotate tires.

priestsls4

again, thanks to everyone who chimes in...this is the best brainstorming in my opinion...people who have both general car knowledge as well as specific experience with our ls cars.

good try on the brakes dashan...thought about that one for a few seconds until I remembered that when I inspected the car it had been serviced up front, including new rotors...although I have not found my culprip yet...she sure does stop good with those tiny little brakes...for now!

keep em comin...and I will keep you all informed (will be putting her on the rack on wednesday if all in my real life goes well!