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PART
3-3-
POWER STEERING
3-35
put shaft bore of the housing posi·
tioned horizontally, then it can be
easily seen when the seal is fully in
against the retaining shoulder of the
bore. It shorlld be noted that this
shoulder is very small and an excessive
assembly load could push the seal
right through the bore making the seal
unusable. Under no circumstances can
a seal be fitted by pushing it straight
into its bore from the input shaft end.
4. To replace the input shaft
bearing, first press the bearing into
the bearing spacer ensuring that
it
is
pushed hard up to the shoulder in the
bearing spacer bore. It is preferable to
use a new bearing spacer when fitting
a new bearing as a reused spacer often
fails to provide any interference fit
between the bearing and/or the
housing. If a loose fit does result, a
new bearing spacer must be used.
S. Fit the bearing and spacer as·
sembly into the housing using the
same service mandrel as used for the
seal, but
only
push
the
assembly to
within about one
tenth
of an inch
from the seal. This can be observed
by parUy withdrawing the mandrel
and looking in through the input
.
shaft seal.
6. The final positioning of the
bearing spacer is carried out by plac·
ing the .010 inch service shim at the
end of the sleeve on the worm valve
and sleeve assembly and entering the
worm valve and sleeve assembly into
the housing. Fit the ball cage, race
and bearing adjusting screw and
tighten the bearing adjusting screw to
push the assembly fully home.
7. Remove the worm, valve and
sleeve assembly and discard the ser·
vice shims. The bearing spacer will
now be correctly positioned to pro·
vide a working clearance for the
sleeve.
8. The function of the bearing
spacer is to prevent any possibility of
the sleeve becoming disengaged from
the worm and as such it constitutes an
important safety feature of the gear.
9. As an additional safety feature,
the bearing spacer has a flange on its
outside diameter to limit the maxi·
mum distance it can be pushed into
the housing, in the event of a failure
of the high pressure seal in the
coupling sleeve. It is important that
the above procedure is adhered to
and no short cuts taken. If in doubt
as to the working clearance between
spacer and sleeve, this can be checked
by placing a small piece of plasticine
on the end of the sleeve, pushing the
worm valve and sleeve assembly fully
into place and immediately with·
drawing it. The plasticine will be
flattened to the thickness of the
clearance existing.
10. Wrap one layer of plastic insu-
lating tape around the valve splines to
prevent damage to the valve seal when
the worm, valve and sleeve assembly
is being fitted.
11. Position the steering gear hous-
ing with the input shaft and sector
shaft bores horizontal.
12. Enter the worm valve and
sleeve assembly in through the bearing
adjusting screw bore and feed the end
of the valve through the valve seal
fig. 52
Bearing
Spacer
Shim in Place on Valve
being careful not to turn the seal
inside out. Push the assembly home
with the thumbs
-
do not hammer
under any circumstances.
13. Turn the steering gear so that
the input shaft is vertical and the bore
for the bearing adjusting screw upper·
most.
14. Drop the bearing cage in posi·
tion on the worm track.
.
15. Enter the bearing race into the
bearing race bore and push carefully
home, keeping the race square as it is
pushed down the bore. Only light
tapping should be required; if efforts
become high remove the bearing race
again by tapping out the worm valve
and sleeve assembly and start again.
N.B. It is advisable to break the sharp
edge on the bearing with a fine stone
·
to avoid damage to the adjusting
screw bore during fitting.
16. With the bearing race fully
home, place the rubber seal on the
race and fit the bearing adjusting
screw. Tighten the adjusting screw
sufficiently to remove end float. (Pre·
load is not necessary at this stage.)
17. Set the gear with the input
shaft and sector shaft bores hori-
zontal.
18. Position the rack pad in the
rack adjusting screw.
19. Carefully enter the piston rack
assembly into the bore of the housing,
being careful not to allow the rack to
touch the bore and support the end
of the rack from inside the housing,
whilst easing the teflon seal past the
threads at the end of the bore. The
piston may be cocked slightly to
assist in passing the teflon seal past
thre~rl~
.
•
0. Position the rack in its mid
p<;snlon ready for assembly of the
sector shaft.
21. Refit the piston cover ensuring
that the rubber seal is not damaged.
If the seal
is
damaged it must be
replaced with a new seal. Using the
Tool No.
XA-374SA tighten the
piston cover to 2040 ft. lbs torque,
ensuring that the spanner
is
pushed
firmly against the cover at all times.
(Refitting of this cover may be left
until fitting of the sector shaft is
completed if required.)
·
22. Position the steering gear as-
sembly so that the input shaft and
sector shaft bores are horizontal.
23. Check that the rack pad is cor·
rectly positioned in the rack adjusting
screw, and position the piston rack
in
its mean position; i.e. with the centre
tooth gap immediately opposite the
sector shaft bearing bush. (i.e., in line
with the rack pad.)
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