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View Full Version : Brakes, test procedures and tips


rx4ur7
01-22-2010, 12:07 PM
Test for brake booster:
Checking without a tester. Check the 3 tests in order.
(1)
1-With engine stopped, depress pedal several times
2-Start engine with pedal depressed
3-The unit is good if the pedal moves down very slightly immediately after the engine starts

(2)
1 start the engine
2- stop the engine after it has run for 1 or 2 minutes
3- Depress the brake pedal by applying normal force
4- the unit is good if the stroke is long the first time the pedal is depressed and becomes shorter as the pedal is depressed repeatedly (as long as rear drum brakes are adjusted properly, to compensate for non-adjusted rears, apply e-brake fully before perfoming this test)

Note If the results of this next test are unsatisfactory, check for damage or improper installation of check valve or vacuum lines. If a problem is found make repairs then repeat test.

(3)
1-Start engine
2-Depress pedal by applying normal force
3- With pedal depressed, stop the engine
4-Keep pedal depressed for ~ 30 seconds
5-The unit is good if there is no change in pedal height.

If it is still pulling to the right, there is something wrong with the left front brake system.
If the pedal is rock hard, check for stuck caliper, wheel cylinder or improperly installed pad.

Air in master

Now if you ran the master dry and you have air it - that can become a not so fun job.

84/85 factory MC's came with bleeders which should work. But there have been exceptions. If bleeding that and the rest of the system does not work you have a couple of options:

1- bench bleed the master either by removing it and doing it in the vise or doing it in the car. On the car can be messy. Have plenty of rags about to pack under the master.

This next one can be done but can be tricky

2- open all 4 bleeders
2a- press the pedal to the floor quickly, hold it there (I have used the stomp method-caution with this)
2b- close all bleeders
2c- release pedal slowly
repeat as needed.

Really helps to have 2 people on this one, can be done by one but is not fun. Trust me I know.
Using 4 bleeder bottles is the best and cleanest way to do this one.

If you stomp you better have some really good tight tubing on the bleeders. Otherwise you will spray everthing on either side of the vehicle with brake fluid. And you will ruin the paint on your 911 or Dino.