Spongy brake pedal - help!

[2002_thundercloud]

Two years ago I did a tundra 231 rotor and caliper upgrade and used good stuff. I have fully bled the system at least three times and still, to get good pedal feel, have to give the pedal a light pre-pump before the pedal feels "just right". I don't buy into the caliper fluid volume difference argument I read somewhere because the piston diameter between the 4Runner and tundra calipers is the same and the diameter of the pistons and their travel during brake application is what accounts for fluid volume, right?.... Think about it for a second...The caliper switch should have no impact on pedal travel.

I believe some air has made its way up to a coupler between the MC and calipers and will not flush out down to the calipers using the old fashioned pedal bleed method OR some air has made its way up to the ABS VSC solenoid area and again, the old fashioned pedal bleed method can't remove it.

Now that you have read that, let me reiterate....VERY Consistently, a light quick primer pump of the pedal produces a PERFECT feeling brake pedal. Without that little primer, the pedal is awkward with very little feedback, as if the rears are working harder than the front.

I asked my local Toyota dealer to bleed them per the TSM and the service manager said they "don't do that" and offered no other help.

So the question: can the clever garage mechanic perform a similar bleed procedure where the ABS / VSC solenoids are activated so that air is pushed to and out of the caliper without expensive Toyota tools?

Thanks,
Todd

 

[Mynameistommy510]

Activating the abs by doing some hard braking on a dirt road or wet road safely, than bleeding all brakes as soon as possible has worked for some people. This is assuming you have a good MC, good cylinders in your calipers, both rear wheel cylinders are good, and no openings in your brake lines.

 

[AZ4Running]

Sounds like you either have air in the system still or a bad/bypassing master cylinder. Pedal bleeding the brakes is the best way ime to get all the air out. Have somone slowly pump the brake pedal 3-5 times and hold down while you crack open each valve on the brakes. Start at the right rear then left rear then right from lastly left front. Be sure to keep the bake res full or you wiol suck air in and have to start all over. If this does not work i wouod try a new master cylinder.

 

[DocW8494]

Replace the Master Cylinder - be sure to bench bleed prior to install. Cheap simple way to at least start the isolation of the systems.

 

[nevada]

Two years ago I did a tundra 231 rotor and caliper upgrade and used good stuff. I have fully bled the system at least three times and still, to get good pedal feel, have to give the pedal a light pre-pump before the pedal feels "just right". I don't buy into the caliper fluid volume difference argument I read somewhere because the piston diameter between the 4Runner and tundra calipers is the same and the diameter of the pistons and their travel during brake application is what accounts for fluid volume, right?.... Think about it for a second...The caliper switch should have no impact on pedal travel.

I believe some air has made its way up to a coupler between the MC and calipers and will not flush out down to the calipers using the old fashioned pedal bleed method OR some air has made its way up to the ABS VSC solenoid area and again, the old fashioned pedal bleed method can't remove it.

Now that you have read that, let me reiterate....VERY Consistently, a light quick primer pump of the pedal produces a PERFECT feeling brake pedal. Without that little primer, the pedal is awkward with very little feedback, as if the rears are working harder than the front.

I asked my local Toyota dealer to bleed them per the TSM and the service manager said they "don't do that" and offered no other help.

So the question: can the clever garage mechanic perform a similar bleed procedure where the ABS / VSC solenoids are activated so that air is pushed to and out of the caliper without expensive Toyota tools?

Thanks,
Todd

adjust the rear brakes properly.

if you have air in the system, it will never pump up solid. it might bring the pedal up higher, but the pedal will still be spongy.
what you are describing, sounds like rear drum brakes being out of adjustment.

 

[absalom]

Was this ever resolved?