by John Logan in the July 2005 RootesReview

You don’t need a fancy brake bleed contraption or even a helper if you want to bleed your Tiger or Alpine brakes. It’s called the Gravity Method. This method will work with other cars that don’t have large vertical loops in the brake lines, valves that can trap a lot of air, or master cylinders mounted low like an open wheel race car. This method is meant for bleeding a system that has been in use, not a bone dry system you are filling for the first time or flushing.

Where does the air come from?

Often air can be suspended in the brake fluid after a complete refilling or flushing. After a few days or weeks, the air will come out of suspension and gravitate towards the master cylinder. There it will rise through the fluid and escape. It may, however, go through the lines to the brake wheel cylinders where it will be trapped. Air in the system will cause a spongy brake pedal with excessive travel.

Here is the process. First, loosen the master cylinder cap so air can easily enter. Check the fluid level in the master cylinder. Then open a wheel cylinder bleed valve. Air will come out first, then a few seconds later the fluid will start flowing. The longer it takes for the fluid to come out, the more air there was in the cylinder. Don’t worry, air can’t flow into the bleed valve because of the hydrostatic pressure caused by the fluid in the reservoir at the higher elevation.

This process does not require that you start with the cylinder furthest from the master cylinder, as would be the normal procedure. You can do any number of cylinders until you have achieved satisfactory pedal pressure.

Try it. It works!

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