Porsche 928 Workshop Manual page 229

928 Differential, Transaxle System
39
Procedure
3. Perf. transverse lock measurement
(locking torque to pressure ratio)
Testing concl. I important information
- Transmission cold / parking brake
released, no gear (driving position)
selected
- Before starting measurements,
close lock once for a short time
(activate full pressure)
- To measure the locking torque,
rotate only in forward direction!
Always measure across adapter
plate at left-hand rear hub
- Lock right-hand rear wheel fully
using the service brake
- Measure breakaway torque / locking
torque at the specified test pressures
using the torque wrench. Do not jerk
when rotating. Advance carefully
from bottom (low value) lo top
until the breakaway torque / lock-
ing torque is reached.
- Establish test pressures using
System Tester 9288, clocking the
transverse lock solenoid valve.
(Drive links /Check transv. lock menu)
Test pressures / measuring process
Measurem. 1 = press. between 0...5 bar
Measurem. 2 ="
" 10...20 bar
Measurem. 3 =" " 20...40 bar
Measurem. 4 = breakawaytorque
500 Nm (369 ftlb) mini-
mum, with pressure held
at 60 bar or above
Measurem. 5 = check pilot pressure
transverse lock. Specified
value approx. 3.0...4.5 ba
Execution I Notes
- Observe testing conditions indicated in opposite
column
- Switch on System Tester. Select "Check transv.
lock"
- Fully close transverse lock by applying approx.
20 pulses (gauge pressure =140...180 bar).
Pressing operating button at tester once = 1 pulse
- Switch to pressure release position and start with
measurement no. 1
- Measurement 1 = gauge pressure 0...5 bar
Set torque wrench to approx. 5 Nm and use
adapter plate to connect to left-hand rear wheel
hub (No. 7). Observe clicking direction of torque
wrench.
While performing measurements, actuate service
brake to ensure that the right-hand rear wheel is
fully locked. Turn torque wrench carefully (i.e.
avoiding jerks) in forward direction.
If the wheel hub does not yet rotate when the
torque wrench clicks the actual locking torque has
not yet been reached.
Adjust torque wrench to higher value and repeat
operation.
The actual locking torque (actual value) is achieved
when the wheel hub turns and the moment when
the torque wrench starts to click is just about
reached.
II the wheel hub turns but the wrench does not yet
click, the torque set at the wrench is too high
(actual locking torque is lower).
l
PSD-Diagnosis / Troubleshooting
D39 - 209
Printed in Germany . XXVII, 1991