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Braking System - (Max 50 Points)
While bad brakes never stopped anyone, they are not that costly to repair or
replace. The 928 has four wheel disk brakes coupled with standard band brakes
for the emergency system. The hydraulic system is a duel master with an
equalizer. On the later models (US '86 up - Euro '84 up) an ABS system was
used.
Fluids and Leaks
 | Reservoir Check the reservoir for the proper level and any
discoloration. The brake fluid is a serviceable item and should
be flushed and refilled every couple of years - sooner if the car has been
driven in high performance conditions.
(Deduct 5 points for old or low brake fluid)
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| Hydraulic - Check master cylinder, calipers,
equalizer and flex lines for leaks. Sometimes the calipers will not show
any signs of leaks but on operation the fluid will be thrown on the inside of
the tires.
(Deduct 5 points for each leaking component)
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Hoses and Lines
| Flex Lines - The calipers are connected to the braking system by
rubber flex lines. On the earlier cars the lines were not protected and
had a tendency to scuff against the frame. Check all four hoses for
wear. Upgraded hoses have a protector that wraps around the hose that
looks like a spring. Hoses also age over time and should be replaced on
older cars with the upgraded lines.
(Deduct 2 points for each bad flex line)
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| Metal Lines - On cars that have experienced winter
conditions it is possible for the metal lines to be pitted and weak.
Inspect all of the metal lines for corrosion.
(Deduct 15 points for rusted brake lines)
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Pads and Rotors
| Brake Pads - Pads and rotors are designed as replaceable
components and as such are relatively cheap. Rotors should be smooth with
no ridges and the pads material about a half inch thick.
(Deduct 10 points for each axle that needs new
brakes)
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| Sensors - Each wheel has a
has a sensor that detects when the pad has worn out. On occasion people
will disable the sensors by crossing the wires turning off the brake pad warning
light. The sensors are wires that run out from the body to the
wheels. Check to be sure that they area actually connected and
working.
(Deduct 3 points for bad sensors or wiring)
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Emergency Brake
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Adjustment - The emergency brake should hold the car
on a hill with about five clicks. If the emergency brake is not working
properly the bands should be checked.
(Deduct 1 point for a bad adjustment)
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Brake Bands - There is an inspection hole in the
rear hub that allows access to the brakes, however, the wheel has to be
removed to use the inspection point.
(Deduct 5 points for worn or non
functioning emergency brakes)
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Power Brakes
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Brake Booster - The brake booster gives power
assist to the brakes. Unlike U.S. luxury cars the brakes on the 928 offer
an excellent feel of the road and will require more foot pressure than most
power brakes. The booster is located behind the master cylinder and has a
hose with a check valve. The booster can leak vacuum causing the engine to
run rough. Run the engine for a few minutes and shut it off for about five
minutes. The booster will
work for about three pumps before the pedal stiffens up.
(Deduct 7 points
for a bad booster)
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ABS - The ABS system started with the 1986 U.S.
model and 1984 Euro. There is a warning light on the dash that should come
on when the key is turned on and go off when the car is started. The ABS
System is located in the left front fender well. It is driven by sensors
on the axles.
(Deduct 20 points if the ABS light stays on)
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