1992 Ls400 Rear Of The Car Shakes

Troubleshooter · December 11, 2003

:) 1992 lexus ls400 (150k) Very noticeable shake is felt when breaking. like something is badly worn out.

could it be the struts?

Troubleshooter

fiveofakind · December 11, 2003

check rear brakes - could be out of round rotors or time for brake pads. just a suggestion.

silvermate · December 11, 2003

yeah, thats a good suggestion by five. i would check the rear brakes and maybe get the rotors are outta wack and need to be machined

Troubleshooter · December 12, 2003

It rocks and shakes even at 5mph. the breaks are fine!

Troubleshooter

mejojo · December 12, 2003

When braking, the main action is that the caliper pistons, and therefore pads, clamp down on the rotor. There's not much to do with the struts, and everything to do with the condition of the calipers, pads and rotors (and ABS system).

What do you mean when you say "the brakes are fine"?

Joe

VMF · December 12, 2003

does the brake pedal vibrates or kicks back? if yes then resurface your rear rotors.

michaelsn · December 12, 2003

I noticed the same thing but it only does it when gently braking at 40+ mph. and it feels like it's coming from the front. No shakes when I slam on the brakes.

I've been hoping it would go away if I get the wheels balanced but after reading this thread I am now concerned it might be something else. (I have'nt had the chance to get the wheels balanced.)

Is there a way to determine if the shaking is caused by:

1. wheels that need to be balanced.

2. rotors that need to be resurfaced.

3. warped rotors.

My pads are at 50% per Lexus dealer. I think it's at 25% when I peeked at it after taking the wheels off to examine the suspensions.

SW03ES · December 12, 2003

There are a couple things that could be, but I dont think a misbalanced wheel is one of them.

More likely than not it is a case of warped (even slightly) rotors. The LS is a heavy car, and the older ones don't have the huge front brakes that the newer ones do. That equals more heat on the rotors, which equals warping. Not a big deal, they just need to be machined, or if they've already been machined a few times they'll need to be replaced.

Could be a manifestation of a bad motor or tranny mount (a stretch though)

Doubt its a misbalanced wheel. With a misbalanced wheel you'd be looking at a constant vibration between specific speeds. For instance, if you were saying you got a light vibration betweem 65-70mph then I'd say misbalanced wheel.

michaelsn · December 12, 2003

Steve,

Thanks. I'll just get a pair of new rotors.

Take wheel off, take caliper off, remove screw take out rotor, put new one in, push out brake pads and put ebverything back. I think it's that simple...

Troubleshooter · December 13, 2003

Even if the rotors are new! do they still have to be machined?

Troubleshooter

jmblimo · December 13, 2003

No, just have the mechanic, or you, wipe the surfaces with some type of brake cleaner or solvent to remove any machining oil that may be left.

Since your front brakes do most of the braking, I would want to check them out when a problem shows up on the rear. Rear brake problems are usually a sign of weak fronts.

I have a friend that has a SC400 that when you brake fairly hard, feels like some one it hitting the back of the car with a hammer. I assume this is simular to what you're talking about. I fyou brake his gently, you don't feel the problem at all.