Vibration Problem

[Em91]

Hey everybody. Today I put new rotors and brake pads on my car. I did this because last week the car started to vibrate when I put on my brakes. After I put on my brakes and rotors the car got worse. The car shakes like crazy when I step on the brakes but the strange this is that the shifter is also rocking back and forth. My mechanic friend says that these new rotors are definately warped which is possible but, has anybody else every experienced the shifter rocking back and forth because of there rotors being warped. I have a 91 ls 400 with all new motor mounts and tranny mount. Please help. :cries:

[90LS400Lexus]

My 90' LS with 234K also does this, but it seems like the rotors do not seem that bad. I can only feel minor pulsations when I brake from highway speeds. I was assuming it was something else. What has me puzzled is that my brake pads are still excellent and the brakes sound like they are "grinding" when I have to quickly stop after highway speeds- such as a freeway exit ramp.

[Em91]

Thanks 90ls400lexus. Tomorrow I am going to get the new rotors cut. I'm wondering if anyone else experienced this and if it was fixed by cutting the rotors. Thanks for the reply.

[Tote]

I'm also getting my rotors cut and wheels balanced tommorrow morning. My shifter is also moving slightly. I can tell when I brake that my rotor need to be cut. Getting the wheels balanced couldn't hurt. Maybe they can just see if they are off balance (for peace of Mind). When I replaced my front tires the place that installed them did not balance or ask if I wanted the tires balanced (crappy service, if you ask me). Nonetheless I drove off and the car started to shake and the shifter moved alot. Went back mad, and had the wheels balanced and all was well. (never went back to the place)

note: My car has 18" wheels and the ride isn't as good as the stock wheels. They seem to amplify each problem.

Hope the cars will be fine tommorrow

Tote

[95LS400Bob]

I'm also getting my rotors cut and wheels balanced tommorrow morning. My shifter is also moving slightly. I can tell when I brake that my rotor need to be cut. Getting the wheels balanced couldn't hurt. Maybe they can just see if they are off balance (for peace of Mind). When I replaced my front tires the place that installed them did not balance or ask if I wanted the tires balanced (crappy service, if you ask me). Nonetheless I drove off and the car started to shake and the shifter moved alot. Went back mad, and had the wheels balanced and all was well. (never went back to the place)

note: My car has 18" wheels and the ride isn't as good as the stock wheels. They seem to amplify each problem.

Hope the cars will be fine tommorrow

Tote

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Something I want to pass on here. I have my own tire balancer. I have found that new tires "move"...in other words..there is some shifting that comes about after the tire is run a while. So brand new tires should go back and get a rebalance. I have proven this over and over on my balancer. Always about the same weight is required to rebalance but it moves near 30 degrees on the wheel. My Toyota truck proved it again today as I had to rebalance the tires.

On the brake rotor deal..the word is the best way to turn the rotors is to have it done on the vehicle. Now I have not done that but I can understand why it would be better with everything torqued up and in place. So for a real true rotor....that is what I would do.

The motor and trans mounts are so soft in these Lexus cars..it is no wonder you can see shifter movement if anything shakes.

[SRK]

If the vibration occurs only when you apply the brakes, then you have a rotor out of true. To have a warped rotor out of the box means you bought cheap rotors perhaps? I buy only factory brake parts for the Lexus, and for other cars I work on factory, Brembo, or Raybestos parts. The day a new rotor needs turning is the last time I buy that brand. That's why you buy new.

You may also have not cleaned the rotor mounting surface, which can cause a vibration as well.

Modern brake lathes can do an excellent job off the car. As infrequently as I turn any rotor, I do use a modern machine.

Lexus rotors are ground to the final finish, and are an absolute work of art to look at. The surface is incredibly smooth and true, and that's the way they perform.

[Em91]

Well everybody I have my rotors cut and the problem is all gone. The brand of the rotors that I bought were Raybestos. Wow the car feels excellent now.

[jzz30]

the thing is the manufacturer does cut the rotor so that it is true but by the time it gets to you people have thrown them around and that can warp your rotor. its not the manufacures fault or your fault its the people that have handled the car before.

if vibration still persists than you can also check for bushing wear in the rear suspension. i had a rear trailing arm bushing go out and it acted just like you described with the moving shifter and pulsing.