This past weekend went up to Big Bear Lake, and on my way down from the mountain i felt the brakes start to pulsate. As i continue to drive the pulsating got worse just as i had a warp rotor. Also, i have heard the chirping and so called dying seal calls when pushing on the brakes. I searched the forum and it sounds like it can be the brake actuator. I checked the pads they are still above 40%. Any one have experience with similar issue? Thanks

 

Did the pulse go away once the brakes cooled off? I overheated my brakes last year going down a mountain with a trailer. We just got burnt brake smell with no rotor warp. We are still on the original brakes and rotors at 95k miles.

 

Wasnt the anti lock system cutting in was it ?

Chris

 

No ABS use that day. It was a twisty 20 mph downhill mountain road. 1500 lbs of trailer was pushing us down pretty fast and we had to use the brakes a lot. Mechanical brakes get used more the slower you go with our hybrids.

The hybrids regenerative brakes work great above 30 mph and we never overheated on any of the faster down hill runs. Additional air flow also helped at higher speeds. There were several times where we were going down hill at a constant 75 mph and the engine was off for 10+ minutes!

 

Rotors don't warp. However, friction pad material does transfer unevenly to the rotors when the pad material reaches its effective temperature limit and causes pulsing. The conditions you mention can easily cause this to happen.

 

I had the same problem after about 15 minutes of downhill travel coming out of the mountains into Borrego Springs. Once the car had cooled down, the problem went away. Not sure if this is a warning indicator or a characteristic of brake overuse. I attempted to alleviate the problem by shifting down from D to B. Previously in winter weather, I never had a problem with an hour of downhill driving from Big Bear Lake. Anyone know why this happened?

 

I just had this yesterday going down a mountain for 20+ minutes.

When the battery reached full charge, (selector in D) the car switched over to more conventional braking as it wouldnt use any regenerative braking. After a while of using the regular brakes i felt the pulsing. It does feel like a rotors being warped, but i dont think its that. I ended up putting the selector to B to engage regenerative braking even when the battery is full. This seemed to have solved the issue but im still curious as to why it felt like i had warped rotors.

 

So are they still pulsating now or did it go away? Riding the brakes down a long grade will heat up the rotors a lot and if too hot, I would suspect them to start warping.


Even if the pads still have life, the rotors can get warped. Of course I've experience this far more on my Chevrolet vehicles vs the Lexus.

 

I guess i am not the only owner had this issue. To answer the question about rotors being warped due to the potential heat on riding the brakes. After the trip I went to my dealer and I had them examine the rotors and they were fine. After that trip 2-3 years ago I went back up to Big Bear Lake again, but in a different time of the year. It was in the early spring and much cooler, and the problem was no as significant as the previous trip I took in Summer. Based on few owner's comments in this thread I do believe temperature is a factor contributing to this pulsating issue. Once it is cooled the problem went away, and it performs fine. Also, my second trip up I had my brakes fluid replaced in a routine service few months before the trip. If temperature is the culprit I believe brake fluid can be a factor as well.