Soooo me and the woman traded her turd jeep liberty
In on a 2008 ls460. 61k miles. Up to date on service.
Mercury/black perforated interior. When we drove the
Car I noticed a vibration from the rear while breaking.
No problem. Got the dealer to knock off a couple bills
And I'll fix it myself. So I install new rotors(raybestos) and
Beck arnley pads. Drove the car. No dice. Since the design
Of the rotor prevents me from measuring flatness, and I can't do a run-out until Monday, I get new rotors. Duralast from the local autozone. Vibration is gone. For a few miles. Then it's back. Seems to be from right rear. High speeds induce this vibration more than low speeds. At this point I'm beginning to think this isn't brake related. Maybe some thing in the rear suspension. Only vibration is felt in the floor. Not the pedal. Not the steering wheel. Has anyone else experienced this problem? This seems to be a great car short of this very annoying brake vibration. Oh I've rebalanced the tires(michelins) and rotated tires. No change there. It will be Monday before I can get to a lift. Just looking for any ideas from anyone who may have experienced said issues, but beyond the rotor/actuator known issues. Thanks

 

The only thing I can think of is alignment if you already swapped out the rotors and it isn't the tire balance. If it is in the rear you wouldn't really feel it in the steering wheel. Does it happen only when on the brakes? The pads should also be replaced as well. Just some suggestions. Hope you figure this out and let us know what you find. Vibrations are annoying.

 

I replaced pads also. It's only during braking. Otherwise rides like it should. No unusual tire wear to be noted either. Ill get under it this evening and check all the bushings and joints around the rear

 

How do you know it's from the rear? At what speed does the vibration start? I had a slight vibration issue that was resolved with a trip to my buddy with a road force balancer.

 

I know it's from the rear because the vibration is being transmitted through the floor into the seat. Not through the steering wheel, as it would be if there were an issue with the front brakes. I personally balanced the tires, and like I said no hop or wobbles. No offense, but I never bought into road force balancing as there are many variables they don't account for. I've used them before and had just as good a ride as a spin balancer. From what I've been reading it seems that what affects one of these cars affects almost all. Oh and the only time anything is felt is when braking. No other time. And of course it's more noticeable when slowing from highway speeds. The reason I feel it isn't a brake issue is because I've replaced rotors, twice, in less than 24 hours, and the problem still persists.
Update...she returned from a day trip. Said sometimes she felt the vibration...sometimes it wasn't there at all. Only at highway speeds. I hope it isn't that actuator. Time to do some more reading

 

Firm believer in the road force balance. If techs do all the required steps as trained, it is much more effective. It detected a 41lb variance in one of my tires. They indexed the tire and situated it on the best position on the wheel..respun and it dropped below 26lbs of excessive force. Car rides smooth as glass AFTER a "zero'd out" traditional balance.

As far as brakes..I had raybestos advanced technology rotors installed on the rear of my old ls460 with akebono proact pads..they were great! I had a similar vibration issue on another car that would come up after a fix..found out I had a caliper partially stuck and it heated up the rotor constantly. .check even proper torque on wheels at 103 ft lbs and also make sure caliper is not sticking

Sent via Club Lexus Mobile App

 

At this point I'm leaning toward an alignment issue. The chances off getting 4 rotors that would be out of spec are slim. The vibration occurs not so much due to speed, but unloading the rear of the car at speed. I'm thinking something is out in the rear. When slowing down from speed, the weight shift to the front of the car unloads the suspension and changes the geometry and starts the vibration.
I know for sure the rotors that were first on the car did have a low spot. I saw them on the lathe with my own eyes. So hopefully I was fighting two problems and I'm half way there. If so looks like ill have an extra set of rotors. Side note...from what I can see the autozone rotors are identical to the raybestos advanced rotors, other than the black coating on the rotor hat.

 

Fixed it.
It was the *front* rotors. Who knew. After reading and reading and taking things about a few times I figured it had to be the front. My thinking was I know for a fact the rears are flat. I took the front rotors off. Both had low spots around .004". Wouldn't think that small of a difference would be that big a deal but when it's turning at 65-70mph it becomes noticeable. But why no steering wheel shake? Because these cars have electric steering! While the system give output similar to a hydraulic system it won't receive input like a hydraulic system. Keep that in mind if diagnosing brake issues on something with electric assist. I didn't see one article anywhere that mentioned a problem like that. Oh well...brakes are smooth as glass and comfortably slow the car

 

Good job, glad you solved your issue. Welcome to the club.

 

Thanks for the welcome! Next up is the wind noise fix. Ill take care of that this weekend