Brakes
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In most cases the vacuum required to operate a power brake vacuum booster should be at least 18" for best results. In most cases anything less than 14" of vacuum will not be enough. Using a vacuum reservoir is not a very good substitute for inadequate vacuum. In cases where there's not enough vacuum, a vacuum pump may be used, or the system changed to manual brakes. | In most cases the vacuum required to operate a power brake vacuum booster should be at least 18" for best results. In most cases anything less than 14" of vacuum will not be enough. Using a vacuum reservoir is not a very good substitute for inadequate vacuum. In cases where there's not enough vacuum, a vacuum pump may be used, or the system changed to manual brakes. | ||
− | If space is a problem, a dual diaphragm booster might be enough smaller in diameter to help. | + | If space is a problem, a dual diaphragm booster might be enough smaller in diameter to help, as long as the booster has sufficient pressure to do the job. |
− | + | ||
+ | ====Some guidelines from MP Brakes:==== | ||
+ | A midsize GM car with disc brakes in the front and drum rear brakes will require at least 900-1,000 psi to the wheels to lock them up. The pressure output of the booster is directly proportional to its diameter, the larger the booster the greater the power assist. | ||
+ | |||
+ | The following assumes 18 in/Hg of vacuum at idle, and 120 psi of pedal force: | ||
+ | *Four wheel disc = 9" dual diaphragm (1200 psi) | ||
+ | *Front disc/rear drum = From the 9" dual (1200 psi) down to a minimum of a 7" dual (900 psi) | ||
+ | *The 8” dual diaphragm booster makes 1,000 psi | ||
+ | *9” single diaphragm 900 | ||
+ | *7” dual diaphragm 900 | ||
+ | *7” single diaphragm 800 | ||
+ | |||
===Brake lines and fittings=== | ===Brake lines and fittings=== | ||