Squeeling Noise

[KY350]

I'm getting a squeeling noise coming from the left hand side of the car. Due to Lexus noise insulation, I cannot hear the nosie when the windows are up. But when the windows are lowered, I can clearly hear the noise and it occurs at low speed, higher speed and turning left or right.

I checked the brakes last weekend and while the pads are lowish on material, they are still useable. So I don't suspect any noise from the pads. All the wheel nuts are on tight.

It doesn't sound like a wheel bearing noise either as that is usually a growning type of noise and this is a high pitched squeel. Any ideas on what may be causing the noise?

[nc211]

Have you had your rotors turned recently? I think rotors becuase I have had a horrible squeeling from my front driver's side brake, when going in reverse, for a long long time. It would change tone when turning the wheel. Last weekend I had the front rotors turned, and no more squeeling. I had no vibration in the brake pedle to make me think they were warped....but they were. Now the car is straight as an arrow and no squeeling. You might want to have the front rotors turned. The pads gently ride on the rotors, and if they're even slightly warped, or hot-spotted, it can squeek like that.

[KY350]

Thanks for the response nc211.

I've had the car for 2 years and not replaced the rotors or the pads in that time. I think i'll take the car to the mechanics shop for a diagnosis as I cannot even tell if the noise is coming from the front or rear left of the car.

[KY350]

Time to conclude this little sqeeling noise.

I had time to check my rear brake pads again. Took off the outside pad on the left rear of the car and while the pad material is low, its still useable. In fact, I noticed that there is a metal wear indicator on the pad and the pad material was still a couple of millimeters above the wear indicator. When I checked the inside pad, I noticed that the pad was worn down to the metal indicator tab and the tab was freshly worn. However, the pad material on this inside pad was as thick as the outside pad, which was still 2mm away from the wear indicator. So I simply pushed the metal wear indicator tab on the inside pad back away from the pad surface by approx 2mm to even it up with the outside pad. Reinstalled pads and test drove the car - no noises.

Summary - if you have a constant squeeling noise on acceleration / desceleration, turning left or right, then check your pads as one or more are likely worn down to the metal wear indicator tabs, which cause a horribly loud squeeling noise to notify you to change pads.

BTW - does anyone know what the thickness of a new rotor for a 91 LS 400 is supposed to be (front and rear)? Also, what thickness on a worn rotor would be considered out of spec and necesitate replacement rotors?