The Spongy Brake Fix

Yes Virginia, brakes can bleed themselves**
So I learned a trick this week which is kind of cool. It's kind of cool, because it takes very little effort to achieve rock hard brakes, after bleeding, or if your brakes are spongy from previous brake work.

I came upon this trick after installing new calipers on the Geo. I didn't quite have the firm brakes that I had expected, and so I searched around online and came upon the mention of this 83 year old man who had advised an individual on the web, just to put a brick on the brake pedal overnight. Surely that can't work I thought, but I was wrong.

A lot of people do this trick on motorcycles with a zip tie, to the brake lever. Google it, and you find this measure of self-bleeding actually works (there are a few deniers). No one seems to know how it works though, though air-bubbles have been seen in the morning following the release of the brake lever. (Note this is not a replacement for traditional bleeding, but often used in addition to it, to achieve better results.)

To me it does make sense, you're compressing the air and the brake fluid. The air becomes dissolved in the fluid (like the fizz in soda). At the same time,  gravity wants to separate the heavier, more dense brake fluid molecules from the lighter air molecules (buoyancy), and under the pressure of a compressed overnight brake pedal, these molecules use the brake fluid as molecular "tunnel" in their dissolved state to arrive just under the brake plunger. In the morning when the brick is removed from the pedal and as the pressure is reduced (much like a can of soda opening), the dissolved air is released (Henry's Principle) past the plunger, into the master cylinder, and subsequently into the atmosphere.

This technique of self-bleeding overnight (not to be substituted for real, traditional bleeding prior to this trick,) works. Air is released, and the firmness doesn't subside with time. It worked perfectly in the Metro, but being the skeptic I was, I had to try it on my Taurus.

My Taurus is very special. It's a rusty Ohio car, and I've never gotten the brakes to bleed right. Likely due to a rusty proportioning valve, I've chosen to deal with spongy brakes for some time. I knew, if this truly worked, and it wasn't placebo, then this was the car to test it on:

How to fix mushy brake pedals.
Note: if doing this on a incline, be sure the master cylinder (aka the front of the vehicle) is facing uphill. The master-cylinder should be at the highest point of the brake system to ensure this works the best.

Step 1: Pin the brake pedal.
 I used a metal pole, placed between the top of the pedal and the seat-back. I used the power-seats to compress the pedal.

Step 2:
Un-do the brake light fuse, or the negative terminal to the battery.

Step 3:
Wait 12-24 hours. Most perform this overnight and it works fine,

(no need to remove brake cap)

...and you know what, it worked. I've never had as firm of brakes on the Taurus as I do now.

Considering the lack of information on this topic, and the fact it almost was lost for all-time by an 83 year old man, I figured it was worth a re-post here.

Got spongy brakes? Give it go, there's nothing to lose, and everything to gain.


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