A week ago I noticed that when I brake, there is a steam coming from under the hood (driving in rain). Now if I do some seriously agresive driving, I see smoke coming from my brakes and rotors get extrimely hot. What's going on? Any ideas?

 

Since you have rims now, the calipers are now much more in open space. It is just a combination of the heat and cool weather during the rain. Kinda like how you can see your breath when it is really cold.

 

Nah, that is not it. It's dry now and I have SMOKE coming out of my rotors after some agressive braking. The car is not shaking when I brake so no warped rotors either.

 

if you DO drive your Lexus hard, your brake could be smoking. Consider the LS 400 is a very heavy car, weight in about 4000 pounds so slow it down take a lot of work

 

yeah if you have rims, they are probly heavier than stock. causing more heat. also check for leaks. sometime break fluid could be leakin onto the rotors causing smoke

 

check for brake oil leak.

dc

 

Check your Caliper Pins. Make sure they are greased good and not sticking. I see alot of cars with brake jobs were the pins were not greased and they were seized or dry. Further, if the pins seize or are dry...your pads will wear out faster,your rotors will warp,your car will pull to one side.your car will shake on the highway,your gas milage will go down. I use Molykote M77 made by Corning which is specified in most factory service manuals.