Defender 90 NAS. Manual — part 60

57

STEERING

2

OVERHAUL

6. Remove set screw retaining rack pad adjuster.
7. Remove rack adjuster and pad.
8. Remove sector shaft adjuster locknut.
9. Remove four bolts from sector shaft cover.

10. Screw in sector shaft adjuster until cover is

removed.

NOTE: Sealant is applied to hexagon
socket to ’tamperproof’ sector shaft
adjuster.

11. Slide out sector shaft.

12. Remove piston, a bolt screwed into piston will

assist removal.

13. Remove input shaft dirt excluder.

14. Remove worm adjuster locknut using ’C’ wrench

LRT-57-007.

15. Remove worm adjuster using wrench

LRT-57-006.

16. Tap splined end of shaft to free bearing.
17. Remove bearing cup and caged ball bearing

assembly.

18. Remove valve and worm assembly.
19. Remove inner bearing cage, cup and shim

washers. Retain shims for reassembly.

NOTE: Should difficulty be experienced,
warm casing and bearing assembly. Cool
bearing cup using a mandrel and tap

steering box on a bench.

STEERING

3

OVERHAUL

Steering box seals

20. Remove circlip and seal from sector shaft

housing bore.

CAUTION: Do not remove sector shaft
bearings from casing. Replacement parts
are not available. If sector shaft bearings

are worn, fit a new steering box.

21. Remove dirt excluder, circlip and seal from input

shaft housing bore.

CAUTION: The use of a seal puller is
recommended to prevent damage to
casing, and possible oil leaks.

INSPECTING

Piston

22. Discard all rubber seals and provide

replacements.

NOTE: A rubber seal is fitted behind
plastic ring on rack piston. Discard seal
and plastic ring.

Steering box casing

23. Examine piston bore for scoring and wear.
24. Examine feed tube.
25. Fit a new feed tube if damaged. Tighten union to

20 Nm, 15 lbf ft .

57

STEERING

4

OVERHAUL

Sector shaft assembly

26. Check there is no side play on roller.
27. If side play on roller exists fit a new sector shaft.
28. Check condition of adjuster screw threads.

Check adjuster end float. Fit new adjuster if end
float exceeds 0.15 mm, 0.006 in.

29. Examine bearing areas on shaft for excessive

wear.

30. Examine gear teeth for uneven or excessive

wear.

Sector shaft cover assembly

31. Inspect cover and bearing. If worn or damaged,

fit a new steering box.

Sector shaft adjuster locknut

32. The locknut is also a fluid seal. Fit new nut at

overhaul.

Valve and worm assembly

33. Examine bearing areas for wear. The areas must

be smooth and not indented.

34. Examine worm track which must be smooth and

not indented.

35. Check for wear on torsion bar assembly pin. No

free movement should exist between input shaft
and torsion bar or between torsion bar and
worm.

NOTE: Any sign of wear makes it essential
to fit new valve and worm assembly.

36. Examine valve rings for cuts, scratches and

grooves. The valve rings should be free to rotate
in grooves.

STEERING

5

OVERHAUL

37. If required, replace all three rings, using ring

expander LRT-57-019. The expander will not
pass over rings already fitted. Remove rings to
allow access without damaging seal grooves.

38. Warm rings and expander tool to aid assembly.

Fit rings to expander, slide expander over valve
and worm assembly. In turn fit rings to their
grooves. Remove expander, slide valve and
worm assembly into ring compressor
LRT-57-020and allow to cool.

Ball bearing and cage assemblies

39. Examine ball races and cups for wear and

general condition.

40. If ball cage has worn against bearing cup, fit

replacements.

41. Bearing balls must be retained by cage.
42. Bearing and cage repair is carried out by

complete replacement of assembly.

Rack thrust pad and adjuster

43. Examine thrust pad for scores.
44. Examine adjuster for wear in pad seat.
45. Fit new sealing ring to rack adjuster.

Rack and piston

46. Examine for excessive wear on rack teeth.
47. Ensure thrust pad bearing surface is free from

scores and wear.

48. Ensure piston outer diameters are free from

burrs and damage.

49. Examine seal and ring groove for scores and

damage.

50. Fit new ring to piston. Warm nylon seal and fit to

piston.

51. Slide piston assembly into cylinder with rack

tube outwards.