V10_P70
05-14-2003, 08:28 AM
Looking to see what modifications that have been performed on the braking systems of 1998-2003 CV, GM or MM. The stock P71 brake distance should be around 148 ft after heat soaking the brakes from 90-0. Here is the test procedure:
BRAKE TEST OBJECTIVE
Determine the deceleration rate attained by each test vehicle on twelve 60 – 0 mph impending skid
(threshold) stops, with ABS in operation if the vehicle is so equipped. Each vehicle will be scored on
the average deceleration rate it attains.
BRAKE TEST METHODOLOGY
Each vehicle will make two decelerations at specific predetermined points on the test road from
90 – 0 mph at 22 ft/s2, with the driver using a decelerometer to maintain the deceleration rate.
Immediately after these “heat-up” stops are completed, the vehicle will be turned around and will
make six measured 60 – 0 mph impending skid (threshold) stops with ABS in operation, if so
equipped, at specific predetermined points. Following a four 4-minute heat soak, the entire sequence
will be repeated. The exact initial velocity at the beginning of each of the 60 – 0 mph decelerations,
and the exact distance required to make each stop will be recorded by means of a non contact
optical sensor in conjunction with electronic speed and distance meters. The data resulting from the
twelve total stops will be used to calculate the average deceleration rate which is the vehicle’s score
for this test.
DECELERATION RATE FORMULA
Initial Velocity*(IV) squared (IV)2
Deceleration Rate (DR) = 2 times Stopping Distance (SD) = 2 (SD)
EXAMPLE:
Initial Velocity =89.175 ft/s (60.8 mph x 1.4667*)
Stopping Distance =171.4 ft.
(IV)2 (89.175)2 7952.24
DR= 2(SD) = 2(171.4) = 342.8 = 23.198 ft/s2
Once a vehicle’s average deceleration rate has been determined, it is possible to calculate the
stopping distance from any given speed by utilizing the following formula:
Select a speed; translate that speed into feet per second; square the feet per second figure by
multiplying it by itself; divide the resultant figure by 2; divide the remaining figure by the average
deceleration rate of the vehicle in question.
EXAMPLE:
60 mph = 88.002 ft/s x 88.002 = 7744.352 / 2 = 3872.176 / 23.198 ft/s2 = 166.9 ft.
*Initial velocity must be expressed in terms of feet per second, with 1 mile per hour being equal to 1.4667 feet per second.
BRAKE TEST OBJECTIVE
Determine the deceleration rate attained by each test vehicle on twelve 60 – 0 mph impending skid
(threshold) stops, with ABS in operation if the vehicle is so equipped. Each vehicle will be scored on
the average deceleration rate it attains.
BRAKE TEST METHODOLOGY
Each vehicle will make two decelerations at specific predetermined points on the test road from
90 – 0 mph at 22 ft/s2, with the driver using a decelerometer to maintain the deceleration rate.
Immediately after these “heat-up” stops are completed, the vehicle will be turned around and will
make six measured 60 – 0 mph impending skid (threshold) stops with ABS in operation, if so
equipped, at specific predetermined points. Following a four 4-minute heat soak, the entire sequence
will be repeated. The exact initial velocity at the beginning of each of the 60 – 0 mph decelerations,
and the exact distance required to make each stop will be recorded by means of a non contact
optical sensor in conjunction with electronic speed and distance meters. The data resulting from the
twelve total stops will be used to calculate the average deceleration rate which is the vehicle’s score
for this test.
DECELERATION RATE FORMULA
Initial Velocity*(IV) squared (IV)2
Deceleration Rate (DR) = 2 times Stopping Distance (SD) = 2 (SD)
EXAMPLE:
Initial Velocity =89.175 ft/s (60.8 mph x 1.4667*)
Stopping Distance =171.4 ft.
(IV)2 (89.175)2 7952.24
DR= 2(SD) = 2(171.4) = 342.8 = 23.198 ft/s2
Once a vehicle’s average deceleration rate has been determined, it is possible to calculate the
stopping distance from any given speed by utilizing the following formula:
Select a speed; translate that speed into feet per second; square the feet per second figure by
multiplying it by itself; divide the resultant figure by 2; divide the remaining figure by the average
deceleration rate of the vehicle in question.
EXAMPLE:
60 mph = 88.002 ft/s x 88.002 = 7744.352 / 2 = 3872.176 / 23.198 ft/s2 = 166.9 ft.
*Initial velocity must be expressed in terms of feet per second, with 1 mile per hour being equal to 1.4667 feet per second.