I thought I'd share this story for archival purposes should anyone run into the same somewhat unique situation.
I purchased my RX last april, so I've owned it just less than a year. From day one the brake pedal had a lot of travel and felt mushy, and it seemed it took a slight more force on the pedal than any other car I've owned.

I brought it to a local Toyota dealer the first week I owned it. The confirmed the pedal felt 'a little soft', and suggested a brake fluid exchange, but also felt it wasn't outrageously abnormal. I then did other repairs they suggested with a private mechanic, who also spent time with the car and said brakes and fluid were fine and not to mess with it. I then took it t a Lexus dealer for a recall, and again mentioned the brakes to them and they said it seemed normal, and suggested the brake fluid flush again.

Ultimately, the car drives great and I've accepted it as 'normal'. However, I had my tires rotates at a Mavis of all places, and they notice abnormal pad wear on one side. The mechanic suggested the caliper maybe seized. I'm not a fan of Mavis and they always find things 'wrong' that urgently need to repaired, but rarely are they issues that are significant. They did however have a brake flush special for about $39, so I figured it was worth it and it needed fresh fluid anyhow. It made absolutely no difference to the pedal feel.

I ordered a caliper for about $40 from rockauto, and replaced it today. Low and behold, after putting on the new caliper and quick bleed from that one line the brakes feel PERFECT! There is virtually no pedal play now whatsoever, and the it takes nearly any effort to bring the car to a quick stop.

I suppose in the defense of all the mechanics, this tell tale sign of uneven brake pad wear could easily be missed when all the pads are new. I'm not sure if there are any other things that would make this obvious, but I'm really happy the brakes feel like new.

I also ended up replacing all the pads on the front, as I suspected only the passenger side of the car was doing all the work. Sure enough, when I looked at those pads they barely had life left (with about 10,000 miles on the pads). The pads came in a set anyhow, so I replaced those.

I feel I saved thousands here - the roadmap for Toyota was brake fluid flush, then a master cylinder, and finally a brake booster. I'm guessing it would of added up to over a $1000 going down this road and the brakes would of felt exactly the same.

It took about an hour to get everything done, I will note the caliper replacement was a complete package with the caliper mount. However, my impact wrench wouldn't budge the 17mm bolts holding on the caliper mounting bracket, and it looked in fine condition so I didn't mess with it - didn't want to risk stripping screws or shearing it off.

I did take video of the caliper replacement, and in turn pad replacement (2004 Lexus RX330). I'll post it soon and share it with anyone who might be interested. It was fairly straightforward.

 

Thanks for the info....

 

Wow! very interesting. thank you.

 

The entire caliper is not that much harder to replace if you already know how to replace rotors and pads. just need to make sure the brake fluid is bled afterwards though! one of the pins was seized on an accord i was working on. rather than hurt myself trying to get it off i just ordered a new caliper on rockauto just like you and the job took less than an hour to swap it, and bleed the side.

 

Correct - the caliper is very easy to replace. I was away this weekend, but I will update this post with a video of the job very soon.

To bleed the system, I used a simple $5 bleeder tool from Harbor Freight. Replacing only one caliper, there should be no need to bleed the entire system, only the one line that is introduced to air (of course if you go pumping the pedal without a caliper you will suck in a lot of air and liekly need to bleed all the lines). It took about 6 bleed cycles of pump, pump, pump, hold pedal , open valve for a second, close valve. The last two were for good measure, I didn't see anymore bubbles. This is a two man operation to bleed the system.

 

Had the same problem on a 2005
I would push the brake and it would feel mushy. Then with more force it would go further down almost do the ground.
I lubricated all the pins on the caliper.. One was very dry.
Changed the pads which had more than 50% life
FYI: autozone has pads with lifetime warranty. Cashier says whenever they wear down just bring the in and get new ones.

 

Glad to hear it was an "easy" fix. Just because they're Lexus/Toyota trained mechanics, doesn't make them All-Knowing geniuses.

 

Thanks guys, having the same problem with my 08 GS 350,
Had the breaks checked today at Mavis visually and everything looks almost new ..

 

This has beeen a problem on nearly everyLexus I’ve had, being in the rust belt doesn’t help and the pins seize, usually can get away with cleaning these instead of replacing the whole caliper, but the Rx was the exception where both rear calipers were shot. Now every time I switch snow tires over, I clean the pins too, regardless of whether or not there are symptoms that they are sticking

 

Caliper slide pins seizing are a problem on just about every brand of car, not just Lexus. Usually you will notice that one pad on a wheel is wearing out faster than the other. Considering that all cars have this problem, I'm surprised that it has never been fixed.

 

Thanks for all the help, I just did drop the car off at the local muffler shop, the mechanic said he had no issues with the breaks