dunn378

I have a 91 ls400 and I have a severe vibration and shaking when I reach about 50mph. If I continue to drive at a steady speed like 60mph the shaking will stop until I slow down and accelarate back up to 50mph. There is also a knocking noise from the front end when I go over bumps. I just bought the car and everything else seems fine. Has anybody had the same problem or can anybody shed some light on my situation? I put the car on the lift and I did'nt find any play in the front end. I don't think it's a problem with the wheel balance because it seems to be too severe. Also the car is equipped with air suspension. Anyone's help and suggestions are really appreciated!!

Rice

There are a few things you should check as far as vibration goes.
The first and the cheapest one is the balance.
All 4 wheels must be balanced. If you balanced them and the vibration is still there, make sure that the rims are straight. The only way to be sure is to swup the rims from front to rear. That's what I had to do. When I made the swup, I noticed a change in the vibration pattern. It began vibrating at a different speed. This still won't tell you which wheel is bent. Try replacing each wheel with your spare. If you'r lucky, one of the swups will eliminate the vibration.
Eventually, my friend wrecked his LS and I scavanged his wheels. That solved the problem for me.
Another reason for vibration could be your struts. If they'r bad, the wheels start jumping up and down after hitting uneven road. Among other things, struts are supposed to stop them from from doing that.
For the sake of your retirement fund, I hope it's the balance or the rims, and not the struts.
Good luck.

dunn378

yeah i know what u mean especially because i got the air ride suspension. thanks for the feedback.

95ls400

I have the same experience like you too, vibration at a speed in my old Honda and I check everything, wheel, tires, balancing, play in suspension and found nothing. After fight with it for 3 months finnally my mechanic found the problem: lower ball joint. It still intact and not crack but when the car get to high speed, there is a lot tress put on the ball joint and it give up. So check your ball joint as well after you check everything and I hope you will foudn the problem

dunn378

thanks, i'll check it tomorrow. thanks again!!

Lvangundy

I just replaced my front right lower ball joint.

https://www.clublexus.com/forums/sho...threadid=69404

Car runs a little smoother, and the new joint raised the car on the front right a bit. Now I want the other!