PAGE 9 © Copyright Hewland Engineering Limited 2001-2009
a) Determine the correct fixture settings to achieve the correct backlash at a given bearing pre-load.
(See illustrations on following pages)
It is assumed that the pinionshaft is fitted and set at the correct position inside the maincase.
Build the differential and then press the bearing inners (7) onto the journals and mount the crownwheel onto it. Fit spacer (22) into the
maincase bearing bore, followed by a nominal amount of shim (21). A good starting point is probably 0.040”
Fit the dummy bearing outer track SK-1715 to the maincase followed by the diff assembly. Fit the second dummy bearing outer track
SK-1715 to the setting fixture and position onto the maincase. Secure the fixture to the maincase using all 12 nuts (55) and torque to
35Nm.Ensure that the pinionshaft does not run out of backlash whilst tightening the sideplate fixing nuts and add shim if necessary.
Please note that it is important to use all nuts torqued to the correct setting, as this affects backlash readings.
Fit the nut (SK-1718-A) to the setting fixture (SK-1718-B or SK-2066 for JFR) and wind it by hand into position behind the bearing until
a firm ‘stop’ is felt. Use a suitable rod to engage in the hole in the nut if necessary. Unwind the nut by a quarter turn, then whilst rotat-
ing the pinionshaft backwards and forwards, wind the nut in by hand until a firm stop is felt. This is important as it ensures the diff is
correctly seated in it’s bearings. With a marker pen mark the position of the ‘0’ line on the nut on the setting fixture.
This is the 0 bearing pre-load point.
Undo the setting fixture nuts (55) by half a turn or so to release the pressure from the maincase. Wind the nut (SK-1718-A)back into
the fixture to the position where the line marked on the fixture lines up with the number on the nut that equates to the pre-load that is
required.
The nut has a number of lines scribed on it and the number next to it is the pre-load in thousandths of an inch. For example 10 equates
to 0.010”.
The specified pre-load is 0.010” to 0.013” which is ‘10’ to ‘13’ on the nut.
CW& Pinion backlash setting
And Differential bearing pre-load setting
Special Tools Required: SK-1718-A, SK-1718-B (for JFR use SK-2066), SK-1715 and SK-1913-A
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