Can't Get Rid Of The Vibration

[agc]

I have searched the forum and have come up with several things that could be causing my vibration problem. But I am not sure which one to tackle first. Here is my scenario:

About a couple of months ago, I had my strut bar replaced, due to a clunking noise I heard from the front end and vibration during higher speed (65-70 mph). After the strut bar was replaced, I noticed a vibration even more at around the same speed. I figure that my wheels/tires needed to be rebalanced. At the time I knew I was going to change out my wheels/tires to 18” (factory 16” were on the car), so I figured I wait till I get my new wheels instead of wasting money getting the 16” rebalanced. A couple of weeks ago I got new 18” wheels/tires for my car and felt the vibration at the steering wheel between 45-50 mph and again at 70+mph. I took the car back to get tire shop this weekend to get the wheels/tires rebalanced. Afterwards, I noticed that the vibration on the steering disappeared, but noticed that there was a vibration in the car (seats, floor pan, etc.). The vibration is in the front and the back seats and is pretty noticeable. Now I am not sure what it could be, I am thinking another rebalance and also read in the forum that it could be the transmission mount. I am not sure how to determine if it is the transmission mount, but I do feel a slight vibration in the shift knob when I accelerate. Can you guys help me out my car a 2000 LS with only 42k miles, this is driving me crazy

[nc211]

Bingo! I'm in the exact same boat!!! Last diagnostics was bad belt in tire. I'm hoping that's it and will replace the tires in a few months. They need it anyway do to tread depth won't pass state inspection in a few months "at 4/32" now.

I'm curious about something here, and I've posted this up before. My vibration showed itself after I changed up my suspension stuff too, primarily those strut rods. I'm wondering if those new strut rods are confussing the mechanics on the caster/camber settings??? The dial indicator is the same one from the old ones, but I'm curious if new manufactoring techniques of the new strut rods and rubber bushing material used has skewed the setting number requirements??? Any thoughts on this guys? Or just pure rubish.

[branshew]

Tires on the LS can be hard to balance properly from my experience and others on the board. Usually when you feel the vibration in the steering wheel it is in the front tires and when you feel it otherwise it is on a rear tire.

Bad balancing usually shows up at certain speeds and goes away at others. If your vibration changed the speed at which it appears after you got new tires & wheels then I would almost say for sure that it is in the balancing.

[SRK]

The lower the profile tire, the more critical the balancing becomes. For both of my cars the vibration cure was to have the tires balanced on a road force machine, and the results were beyond belief. Find a shop that can perform a road force variation balance.

[alsalih]

I think you guys are on the right track here. What I believe is happening is that after you replace a strut rod or any other suspension member which was worn or loose then you have now created a firm or solid joint which was previously absorbing the tire and/or balance imperfection. The new firmer/stiffer suspension components are now directly transferring the load and that's why it's becoming so evident after the suspension work. It's now more critical to have a correct tire balance as any imperfections would be transferred and felt right away. If you feel vibration in the steering wheel then this indicates a poor wheel balance job, however if you feel front end vibration without steering wheel vibration then this could also be caused by an out of round tire or bad belt as nc211 has (Lexus manual calls for checking this, don't have the number handy but I can tell you 3 out of 4 of my Goodyear’s Eagles were out of spec which is causing my problem). Also, I think it's important when replacing a strut bar to inspect the lower ball joint by removing it from the hub, and to inspect the lower and upper control arm bushings. You really need to disconnect the ball joint from the upper control arm and the lower ball joint from the hub to be able to do an accurate inspection. Good luck.

[nc211]

agc, I agree with the guys, especially SRK and the road force balancing issue. I would recommend you find a place that has the Hunter equipment. Here is thier link http://www.hunter.com/. I hear this is the best stuff on the market, and most dealerships have it. It should be noted that I do not have the 18 wheels, just the stock 16 that came with the car. I know lower the profile, harder the sidewall the tire has, which reduces the flex in the tire over bumps.

edit: here is the site to find the 970 machine in your area. Look at "locate a gsp97000" at the top right. http://www.gsp9700.com/

[prix]

If you want to rule out motor mounts as the cause, here's what someone told me to do.

start car

put car in drive while keeping foot on brake

keep foot on brake while pumping gas pedal

have someone watch the engine while you are revving it

if they see vibration etc., you need new motor mounts

a mechanic can also guesstimate the condition of the mounts (engine/tranny) during on of their point by point inspections...

does this make sense? i never tried it (mechanic eyeballed the mounts and said they were in good condition)....

agc, I agree with the guys, especially SRK and the road force balancing issue. I would recommend you find a place that has the Hunter equipment. Here is thier link http://www.hunter.com/. I hear this is the best stuff on the market, and most dealerships have it. It should be noted that I do not have the 18 wheels, just the stock 16 that came with the car. I know lower the profile, harder the sidewall the tire has, which reduces the flex in the tire over bumps.

edit: here is the site to find the 970 machine in your area. Look at "locate a gsp97000" at the top right. http://www.gsp9700.com/

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[nc211]

Prix, you're close. What you're looking for when you do that is excessive engine shifting in the bay. The engine will flex a little since the mounts are rubber. What you're looking for is excessive shifting from driver's side to passenger side. Sometimes you'll hear a clunk noise when doing this. This is a clear indication the mounts are toast as the torque is compressing the rubber beyond tollerance. Basically, if your engine shifts more than and inch or two, they're bad.