Hi all, i am a GS owner from Hong Kong....

My GS has soft brake issue since i bought. The brake pressure is v low until i pump the pedal again immediately. I have searched a lot of threads in this forum and followed some solutions as you guys said. But the problem still exist and the situation is worsening.

I have changed the master brake booster, brake line, bleed the brake many times but no improvement at all. The garage has checked all calipers and said they are normal. So any solution for my brake? I need all your help~

 

Brake master cylinder. You need to get the entire unit replaced. For some reason, Lexus really dropped the ball in that area.....Judging from this issue, I'm going to assume you have 98-00 model?

 

I had the same issue. How do your brake pads look like? Do the inner ones look like they are wearing out faster than the outer ones? If it does, then your problem is the caliper bracket. Mine had the same issue when I bought it. I didn't go as far as replacing the master cylinder but I have replace the brake rotor, caliper, and pads. With the new pads on, it seemed like the pads were locked on the rotor. I realized that the people who have been changing the pads on my car only loosened the lower caliper bolt and removed the top one to flip the caliper down then threw pads in and flipped it back and called it a day. The problem is the lower caliper bolt ran dry of grease and rusted into the caliper bracket. So when you brake, only the top caliper bolt moves, the bottom doesn't. This is why it's important to lube ALL your caliper bolts/pins before reinstalling your pads. Let up know if this works for you. Keep us updated. The most annoying thing is when a member has a problem and they don't update the thread with the solution. It may be other things but your problem sound very similar to mine.