Lexus RX Brake Issues
Link to Club Lexus thread on Brakes
After removing the wheel, in this case, one can see a scored disk. The pad has probably been worn down and not replaced soon enough. The disk can be turned (smoothed out) or replaced. Some may leave it as is and just install new pads, letting the new pads do some smoothing - not recommended as the disk must maintain a minimum thickness to be safe.
The pads can be inspected and replaced by separating the caliper piston from the rest of the caliper housing. Remove the lower slide-pin bolt and swing the caliper piston up to clear the disk as below.
With the caliper piston swung up, tie it off with wire (coat hanger will do nicely). The pads remain on the disk and may be removed for inspection.
For pad replacement it is very easy and does not require removing the entire caliper, just swing it up and out of the way.
Rear Caliper Problem
On my particular RX, which lives in the northeast with plenty of road salt, both rear calipers developer a problem. On both inner sides of the rear disks, I noticed rust on the inside disk surfaces. Unusual because the pads always clean off the surfaces. After pulling apart the calipers, it became clear the calipers were not floating properly on the slide-pins and therefore the inner pads were not being pressed against the inner surfaces of the discs. The inner surfaces were heavily rusted.
To correct this, the disks were removed and cleaned. But the problem was caused by the slide pins becoming stuck and no longer sliding. Shown below the pins can be removed and cleaned, lubricated with high temp brake grease and reassembled. The brakes are working great now!
Inspect both sides of the disk. The rear disks are a solid piece. The front disks are ventilated (cooled). The rear disks are easily removed by just pulling them off the hubs. The front are a different story.
For full inspection, removing the entire caliper may be necessary.
Always support the caliper to avoid putting strain on the hydraulic line.
Took me a while to realize what was going on here!
Here is an unusual front brake problem. I had a strong vibration from a wheel when braking, hard to tell which wheel. As I was inspecting the brakes and disks, I had to actually look twice at this front disk before I notices the problem...
Yes, after 129k miles the ribs had rusted through on about 1/2 of the disk. The cracked ribs allowed the disk sides to compress when braking, thus causing a major vibration as the disk turned since the other half of the disc maintained the original thickness.
Yup, rotors had to be replaced! Interesting that I have driven many vehicles over 100k miles, some as much as 300k and have never seen this before. Must be a new kind of road salt ;-)