Hi guys,

Need help. I feel a slight brake pedal plusation when braking from highway speed, and the shifter **** oscillates as well. Any idea as to where is coming from? I check all four brake rotors with a dial indicator and the runout is less than 0.002", can't figure out what might be causing the plusation.

Appreciate any help.

DJL

 

automatic brake pressure distribution on later Lexus models.

My 01 AWD RX will often do as you describe on a slight downhill run while moderately braking, even worse if the street is wet. Pretty sure it's not the ABS kicking in.

 

Wwest,

Thanks for the reply, forgot to mention my SC400 is a 93. It just has standard ABS and traction control. Would a slightly sticky piston cause the pulsation? All pads are wearing evenly and I change the brake fluid every year.

DJL

 

Were the rotors new or turned?

If they were turned, you wouldn't necessarily have a runout issue when measured cold, but could still exhibit a rotor vibration when heated up. Turned rotors ALWAYS suck!

 

Just an idea, but could it mean that the calipers are not rebounding all the way back? I warped the rotors in front long time ago and then what you described developped. Then again, I am not a mechanic.

My solution to my problem is replacing the brakes with Supra TT brakes. The calipers are assemmbled sitting in their boxes. Can't wait to put them on.

 

You need new rotors. Were the rotors recently turned? Same thing happen to my SC. AutoZone has our rotors for $55 each or you could buy from Steve Ganz TRD rotors for $90 each

 

Stock rotors, never turned, no score marks of any kind. I bought the car new in 93, it has 96,000 miles.

Thanks for all the feedback.

DJL

 

What happen/work done before this vibration happen?
I had problem with my front brake (long story) but what you describe was exactly what happen to my car. Finally replace new rotors and problem when away.

 

Okay...

So it sounds like you factored out the brakes as being the real root cause of the pulsation. So that leaves just a few other things. Some said maybe the drivetrain....but I haven't seen that really make a difference on my SC. So I would next look at the wheels, and tires.

Are your wheels factory? If yes, have you balanced or checked them for round?

If no, then are the hubcentric and centered? Are they balanced and round?

That's my .02

 

ROTORs--
..front rotors vibrate steering wheel + shift ****
rear rotors pulsate brake pedal

Get those fixed with new pads and you'll be fine.

 

Have all 4 rotors turned if they have never been. After 96K miles, they need it reguardless if it solves the problem or not. You'll end up braking better. So for less than $20, it's a quick and cheap way to try to solve the problem.

 

I have this problem,
recently i changed my brake pads to new pads but i didn't get any work done to the rotors, the car is a sc400, 1992 and has 70k miles.
after changing all the pads i noticed that while braking at highway speeds there is a pulsing thru the brake pedal, could this be the ABS coming on?
if i'm just driving in the city i never get this feeling no matter how hard i hit the brakes.
whats the problem that i'm getting?

 

you changed the pads, didn't turn the rotors, and wonder why the brake pedal pulsates?

Odds:

ABS- 2%
not turning the pads like everyone else - 98%

............and lemme highlight the key phrase:

Of course it is the rotors, you alway have to turn them. The old pads have grooves worn into the rotors.