ukrkoz

Son has now 07 LS.
We bought it with very strong vibration, when braking, pointing towards the rotors issue.
Seller showed a receipt from a shop, saying that the rear pads and rotors were replaced. Not sure when, how long ago.
I replaced front rotors yesterday.
That vibration is mostly gone but, there is still some slight back-for jerk braking. Literally, back for, like as if ABS is engaging. Like brakes grab and let go. Nothing major, car is very driveable, but it can be noticed.
Front rotors were toasted. Instead of nice grey, they were dark brown shade, pointing towards major overheating. NO DRAG spinning wheels though. Looks like previous owner laid on brakes heavy.
Anyhow. I am trying to find out, how long ago rear rotors were replaced, maybe we simply need to turn them.
Otherwise, what would cause that light grab/go shimmy?

Boykie

ABS unit on the way out.

ukrkoz

There is no ABS lights when this happens. As in - NO warning lights whatsoever, and, otherwise, ABS shows them, when wheels slip and traction kicks in.

alsuwaidi

I would first reset the Brake memory and then reprogram the ABS.
If that doesn't solve it or if it comes back again after a while I would recommend replacing the brake fluid ASAP to avoid problems. Then reprogramming the ABS. (use Lexus procedure to replace fluid to avoid problems and ensure full bleed)

There are multiple threads here explaining the bleeding with valuable PDFs containing the procedure.

Is the vibration happening when braking at low speed? or at high speeds only?

swfla

iTrader: (1)

Not disagreeing with Boykie, but new rotors and brakes can be warped if not bedded in correctly. I had this issue when I bought my used car. The rears rotors and brakes had been replaced by previous owner recently at Lexus. Rock Auto has great options. I had a shudder, so replaced them again. Solved the problem. Turning rotors isn't an option, too thin, especially if warped.

Gerf

How would you go about doing that?

alsuwaidi

You’ll need toyota software “Techstream” to do that.

Gerf

I've seen the reset memory for different systems , are you using flash files to update the ecu ? I'm not sure what you mean by re programming the abs.

Striker223

Actuator offset learning most likely

ukrkoz

I think I got it figured
I looked at the previous owner repair slip and they replaced only ONE rotor, rear left.
Safely bet, the rear right is giving that shimmy. Beats me, why they replaced just one. And a cheapo one to that, $65. I guess, the left one was worn out. I'll check for binding.

KISS.

Boykie

Son's car? Heck, get all 4 original toyota rotors and matching new pads. It's your son. These are brakes. Car weights 5000lbs.

Striker223

The Toyota rotors and pads are some of the worst options, they warp easily and the compound fades quickly and dusts a lot.

swfla

iTrader: (1)

You missed the point. Boykie's advice of new brakes and rotors for the man's son is sane advice.

Bigguy818

When I bought my Lexus last year end of august, it had so much vibration /brake pulsing and at the time I had the shop re surface my rear rotors then voila, car drives and stops like a dream.

The technician that resurfaced my rotors said they were messed up and had to be changed in the next brake job.
here I am a year later and 12k miles later and my Lexus Ls 460 drives like like a dream and puts a smile on my face every day on my way to and from work.

start with resurfacing the rotors and I hope that helps.
cheers.

alsuwaidi

6 months ago I’ve did a DIY flush of my brake system using Techstream following the repair manual. Then reprogrammed the ABS. The old fluid was 4 years old. Brake fluid is supposed to be changed every 2 years since it attracts moisture from the environment. Right away I’ve noticed the ABS’ priming sound is whisper quiet, not like before where you’d hear it from a mile away. Also, the braking performance improve dramatically that I’ve decided to flush the brakes of all the other cars at home(the LS was the hardest to do).
Last month, I replaced the control arm Bushings, two days later the brake system light came on. I restated the car and it was gone. Then the ABS started acting weird. Sometimes it will brake normally and suddenly it will apply very strong brakes that the whole car would shake. So I drove home pulled my laptop and reset the brake memory then reprogrammed ABS and problem is gone.