1996 Lexus LX 450 Spongey Brake Pedal Issue (1 Viewer)

[BigCarSmolBoy]

Hi all, I'm coming to ask for help with my car. I've sunk 3k so far into trying to fix this issue but it still persists. Here are all the things I've had replaced by the mechanic.

• New Brake Master Cylinder
• New Brake Master Booster
• Adjusted Brake Master Booster
• Replaced RHS and LHS (Front) Calipers
• Replaced RHS and LHS (Front) Rotors
• Replaced RHS and LHS (Front) Brakepads
• Multiple Brake Fluid Flushes with visual inspection of lines. No rush or leaking, they are still good to go.

I'm not sure if this is a contributing factor to the Spongy Brake, but I was told that the front axle is leaking on both sides.

Additionally, the car has a little over 463,000 mi.

The issue with the car is that when I brake, it doesn't feel responsive. The car slows down rather than being able to stop fast, if that makes sense. When you hold the pedal, it slowly sinks to the floor, especially when I'm braking.

I've posted in other numerous places, and they all suggest it has something to do with the ABS, but I get more opinions.

Thank you for your help.

 

[nukegoat]

First, 80 brakes suck

Secondly, if you can hold down the brake pedal and it slowly sinks then I suspect your "new" master cylinder aint so fresh

 

[SNLC]

Rubber lines possibly. If old they can swell when you brake.

If lifted, LSPV can make it feel like the brakes suck. Adjust the LSPV or better yet dump it and put in a proportioning valve.

What kind of driving do you do? There is such a thing as pads glazing.

New aftermarket rotors can sometimes take some time to break in, before this they feel kind of weak.

Cheers

 

[MLX450]

Somewhere there is a thread where you have to activate ABS, bleed brakes, (do this several times).
463K miles! wow! I would replace all rubber brake hoses and check the booster and its vacuum hose (cracks/leaks). There are reports that brake boosters fail out of the box, especially if you get aftermarket ones.

 

[KenH]

reman booster ?

 

[Kay9Cop]

I had a similar issue in my 4Runner. I could bleed and get a firm pedal, but as soon as I actually used the brakes while driving it would go soft. It was air in the ABS circuit. During braking the circuit would open and allow unbled air into the brake system. I used Toyota’s Techstream software to activate the circuit during the bleeding process and the problem went away. I don’t have a CEL on my new to me LC, so I haven’t hooked up Techstream to see if that function is available on the LC. Others can probably chime in on bleeding the ABS.

You may want to have your brakes bled by the dealer and make sure they use their software to bleed the ABS as well. If you ask about bleeding with Techstream and they seem confused, go to another dealer. I went to a dealer with my 4Runner that said they would do it, but it came back with spongy brakes. I had them re-do it and I stayed for the process, only to see them just bleed the old fashioned way.

 

[Kay9Cop]

Oh, and the poor man’s way to do it without the software is to hit a gravel road, activate your ABS, and bleed again. Repeat about a dozen times and you should have most of the air out.