IPA Tools 7884 Disc Brake Analyzer - Manual

5. On Integral ABS systems with 4 wheel disc brakes, you will see the
following on the #7884.
(a) Normal pressure on the #7884 when installed in the front, even
after pumping the pedal 20 to 30 times with the key off indicates a
depleted boost assist and accumulator pressure. However, you
must remember that master cylinder pistons supply the front brakes
at all times. A high hard pedal will be present but you will still have
front brakes even with the key off.
(b) With the system charged (accumulator charged), turn the key off.
Install the #7884 the rear calipers and pump the brakes. As long
as you have power assist, you should show pressure to the rear
caliper pads. When the accumulator pressure is depleted, you will
lose power assist and rear brake pressure at the same time. The
key must be off. Approximately 20 to 30 applications will deplete
the pressure.
TROUBLESHOOTING CHART
INDICATION Possible Cause Action
Un even pressure
reading on
gauges.
1. Rear Brake djustment
2. Stuck Proportioning valve
Frozen Caliper Piston or Slide
1. Adjust Rear Drum rakes
2. Replace Proportioning valve
Replace Brake Caliper
Needle drops
slowly.
1. Imploded Brake Hose.
2. Frozen Brake Caliper
If the gauge needle drops slowly open
the bleeder, valve, if the needle
then drops quickly the brake hose
is imploded and should be
replaced. If the needle still hangs
when the bleeder is open, replace
the caliper.
Pressure Readings
are low but
even.
1. Both rear drum brakes are
badly out of adjustment.
2. Bad Master Cylinder.
3. Bad Power Booster
4. ABS System in need of repair
1. Adjust Rear Brakes.
2. Test and replace Master Cylinder.
3. Test, repair or replace power
booster.
4. Test and repair ABS system.
IPA Disc Brake System Analyzer Manual #7884 v02
Disc Brake System
Analyzer #7884
NOTE!
#7884 diagnoses and tests disc brake operations and efficiency.
There is no pressure chart available because caliper pressure is
relative to the weight mass and pressure applied to the brake peddle
which is not repeatable. Rather than looking for a specific pressure
number, look for brake pressure imbalance that can cause uneven
brake ware.
The #7884 is factory sealed; removing the gauge from the tool or use
other then what it was designed for voids the warranty.
Tests:
ƒ
STICKY BRAKE CALIPER PISTONS
ƒ STICKY BRAKE CALIPER SLIDES
ƒ AIR IN THE HYDRAULIC SYSTEM
ƒ PROPORTIONING VALVE OPERATIONS
ƒ IMPLODED (RESTRICTED INTERNALLY) FLEXIBLE BRAKE HOSES
ƒ BYPASSING OR INTERNALLY LEAKING MASTER CYLINDERS
ƒ REAR LINING TO DRUM INCORRECT ADJUSTMENT
ƒ UNEVEN BRAKE PAD WEAR
INSTRUCTIONS
Before installing the #7884:
1) Determine the type of brake system that is used on the vehicle.
The two major types are: (1) split diagonal and (2) split front to rear.
This is a necessary step so you follow the correct repair
procedures after obtaining test results.
2) Determine if the disc brake pads are of the type that can be
removed without removing the caliper/caliper bracket or if removal
of the caliper is necessary, remove the disc brake pads.
3) Zero the red pressure tell tail needle on each gauge by turning the
center knob to the left until the red needle just contacts the black
needle at 0 psi.
INITIAL TESTING
1. On both front wheels, remove the inner disc brake pad and install
the load cell (the rectangular end) of the #7884 place of the inner
pad. Be sure to have the raised round load cell piston facing away
from the brake caliber piston and centered on the disc brake caliper
piston. Depending on the diameter and style of piston, it may be
necessary to place a shim such as the metal portion of a worn disc
pad between the piston and the #7884.