Spungy Brakes
11-21-21, 10:53 PM
#1
Driver School Candidate
Thread Starter
Spungy Brakes
I just recently purchased a 1999 RX 300. It has very spongy brakes and does not stop well. I have replaced Rotors, brake pads, and calipers on all four and The master brake cylinder. when I bled the brakes,I got all the air out of the system.
I still have the same spongy brakes
Any ideas?
I still have the same spongy brakes
Any ideas?
Last edited by bbambrough; 11-22-21 at 06:10 AM.
11-22-21, 09:43 AM
#2
Moderator
Going along with your diagnosis "spongy brakes", you have a bad hose or air in the system. Although you can bleed the air out by the old method, but if you have air in the ABS section, I would suggest that get a tool or go to a place where they can electronically operate the ABS to service mode. Remember the air bubble can still be way removed from the wheel.
Bad hose usually swell up (expand like a balloon) and not provide the full hydraulic transfer of volume to the slave. You have to jack up each end and watch each hose as some one pumps the brake.
There maybe other issues, but then they should not be termed as "spongy".
If you bought the vehicle from a dealer (new/old) then they are required to sell a safe vehicle. If it was a private sale then the responsibility is not on the seller.
Salim
Bad hose usually swell up (expand like a balloon) and not provide the full hydraulic transfer of volume to the slave. You have to jack up each end and watch each hose as some one pumps the brake.
There maybe other issues, but then they should not be termed as "spongy".
If you bought the vehicle from a dealer (new/old) then they are required to sell a safe vehicle. If it was a private sale then the responsibility is not on the seller.
Salim
The following 2 users liked this post by salimshah:
99RX300PDX (12-08-21),
Margate330 (11-22-21)
11-22-21, 10:20 AM
#3
Lexus Test Driver
I see this is your first post, so welcome to Club Lexus.
"Spongy brakes" is a very generic complaint so plz more effort and more description of how and what you mean by spongy, driving conditions, what type pads were installed, etc.
When I bled my brakes it took 1 1/2 quarts to get all the trash & air out of the lines. Without a special way to bleed the ABS- I found good success doing the bleed having a helper pump the brakes with engine off and then starting at front passenger side, rear passenger side, rear driver side, and lastly front driver side. I then start the car so I can use the power assist and repeat the process. The master reservoir doesn't hold much fluid so it's easy to run it dry doing this process and make lots more work for oneself so keep a hawk eye on the reservoir.
Add- when I flushed my brakes using this system it pulled out black juice with floaters while the fluid in my brake reservoir looked fresh and clean- go figure.
Getting the air and trash out of the ABS actuator is very important- there are many valves inside the actuator that can clog with trash and keep the system from holding pressue with sinking brake pedal.
Here is a teardown I did on an RX330 if you want to get an idea: https://www.clublexus.com/forums/rx-...s-invited.html
Like mentioned above, could have a bad hose and can be other things too like a leaky vacuum fitting at the brake booster, crappy brake pads(oem uses semi metallic), and the list goes on depending on what "spongy means".
"Spongy brakes" is a very generic complaint so plz more effort and more description of how and what you mean by spongy, driving conditions, what type pads were installed, etc.
When I bled my brakes it took 1 1/2 quarts to get all the trash & air out of the lines. Without a special way to bleed the ABS- I found good success doing the bleed having a helper pump the brakes with engine off and then starting at front passenger side, rear passenger side, rear driver side, and lastly front driver side. I then start the car so I can use the power assist and repeat the process. The master reservoir doesn't hold much fluid so it's easy to run it dry doing this process and make lots more work for oneself so keep a hawk eye on the reservoir.
Add- when I flushed my brakes using this system it pulled out black juice with floaters while the fluid in my brake reservoir looked fresh and clean- go figure.
Getting the air and trash out of the ABS actuator is very important- there are many valves inside the actuator that can clog with trash and keep the system from holding pressue with sinking brake pedal.
Here is a teardown I did on an RX330 if you want to get an idea: https://www.clublexus.com/forums/rx-...s-invited.html
Like mentioned above, could have a bad hose and can be other things too like a leaky vacuum fitting at the brake booster, crappy brake pads(oem uses semi metallic), and the list goes on depending on what "spongy means".
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