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Dj
Dj, ASE Certified Technician
Category: Toyota
Satisfied Customers: 1910
Experience:  ASE Master Tech, 30+ years in automotive repair.
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Tundra: I got a 2007 Toyota tundra with a soft pedal, just

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I got a 2007 Toyota tundra with a soft pedal, just replaced brakes all around pads and rotors, replaced front calipers, bleed the brakes and still have a spongy pedal.
but with the truck off its as hard as a rock
Hello and thank you for requesting me.
Did your truck have a soft pedal before the brake work?
How much brake bleeding have you done and what method did you use? Pressure bleeder or pump it up, hold it, crack the valve?
I should have read all of your notes. When you bleed the brakes, do you still get air or does the fluid look good?
Customer: replied 2 years ago.
It had a spongy pedal before the work has been done did vacumm and hold and crack bleeding
Customer: replied 2 years ago.
fluid look good
OK, here's the theory behind the problem.
Fluid doesn't compress. So when you push down on the pedal, the fluid moves and presses the brake pad or brake shoe against the rotor or the brake drum.
When you have excessive movement (spongy pedal) it's because of one or more of the following:
There's air bubbles in the system and the bubbles will compress.
There's excessive movement of a brake pad. For example, the rotor can move because the bearings are loose allowing the rotor to twist when the brakes are applied.
There's excessive movement of a brake shoe. This could be brakes that are out of adjustment which would cause the piston in the wheel cylinder to move more than normal.
The flexible brake lines have deteriorated and expanding when the brakes are applied. The rubber hoses have cords running through the rubber. This keeps them from expanding. If the cords are broken the hose will expand in diameter when the brakes are applied, causing excessive movement.
Out of all of these, air trapped in the lines some place is by far the most common. And the ABS actuator is a favorite spot. Toyota makes a special tool to activate the solenoids while bleeding the brakes to get air out of the actuator.
I've had much better luck with a power bleeder. You can move a lot of fluid with one and sometimes that fast movement is enough to pick up the bubbles and move them to the bleeder. Check the ABS actuator and the rear proportioning valve for bleeder screws. Any high points in the system can hold air bubbles, especially if the brake fluid is moving slowly when you bleed the system.
So on this one, I would hook up a power bleeder, put a clear tube from the bleed screw to to a clear plastic bottle and bleed the ABS actuator, then the proportioning valve, then the rear brakes.
If that doesn't fix it, pinch off the flexible brake hose to the front brakes, then pinch off the flexible hose on the rear brakes. This can help to isolate where the problem is. If you pinch off the rears and the pedal gets solid, then you know that's where the problem is.
What the front flexible lines while somebody else is stepping on the brakes. Do they swell up?
Do the front calipers move when the brakes are applied? Does the rotor flex?
Take a look at these things and let me know what you find.
DJ
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