Overhaul Procedure
A. DISASSEMBLY1. With the power steering rack assembly removed from the car, hold the rack over o drain container, loosen the clamps on both bellows boots and pull back the boots to allow fluid to drain out.
2. With a 14 mm flare nut wrench, disconnect the two seal and feed tube assemblies and then, still over the drain, use the Stub Shaft Holding Tool MB213043 to run the rack back and forth to the extremes of its travel to purge all power steering fluid from the cylinder.
3. Clean the power steering unit thoroughly to remove all dirt. NOTE: It is important that the gear be clean as possible, because dirt and dust must not be allowed to get into the spool valve or cylinder during overhaul.
Take time now to be sure your workbench and tools are hospital-clean and that dust is not likely to be stirred up in the work area while you are performing the overhaul. Have a good supply of clean shop rags available.
Remember that some parts are not replaceable (rack housing and pinion shaft, for example) and if these are damages, the entire gear will have to be replaced.
4. Mount the rack in the holding fixture MIT307112 clamped in a bench vise, and then remove the return tube from the valve body.
5. Pull back the boots, and unstake the tab washers with hammer and chisel.
FIGURE 5:
6. Remove the tie rods from the rack (32 mm wrench) (Fig. 5).
NOTE: Hold the rack with a 22 mm wrench so that it doesn't twist in the housing.
7. Turning the Stub Shaft Holding Tool, retract the rack to allow access to the end housing assembly. Note that the end housing is staked in place. Relieve the staking with a punch. Then, with Wrench MIT213038, undo the end housing and remove it.
8. Loosen the staking holding the cylinder locking nut. Then, using Spanner MIT307098, loosen the nut and unscrew it.
NOTE: The cylinder tube is indexed to the gear housing with a stopper pin. To prevent damage to the stopper pin hole in the gear housing when loosening the cylinder locking nut, hold the feed tube fitting with a wrench.
9. Pull the cylinder from the gear housing.
10. With a 24 mm socket, remove the pinion housing end plug.
NOTE: The end plug is staked in place. Remove the staking before loosening the plug.
11. Remove the 17 mm self-locking nut from the pinion shaft, holding the shaft with the Stub Shaft Holding Tool and a 3/8" socket handle.
12. Loosen the rack support cover locking nut.
13. Using Tool MB990607-01, (found on the "Steering" Tool Board) unscrew the rack support cover.
14. Remove the spring and rack support.
15. Loosen and remove the cap screws (12 mm hex) retaining the valve housing and pull the valve housing off the pinion housing.
16. Using a brass drift, tap the threaded (lower) end of the pinion shaft to drive the pinion and valve assembly out of the pinion housing.
17. Withdraw the rack from the rack housing.
18. Using a brass drift, tap out the pinion shaft lower bearing.
19. Now invert the housing and tap out the pinion shaft upper bearing and seal.
20. Using Bearing Seal Remover MIT213048, remove two seals - one from the rack housing and another from the end housing.
NOTE: It will be necessary to expand the tool by screwing in the expanding screw as far as it will go in order to grip the seal tightly enough to remove it.
FIGURE 16:
CAUTION: The tool must not be inserted so deep that it expands into the housing bore (See Fig. 16). If if does, the bore will be damaged, and the tool will not expand far enough to pull the seal.
FIGURE 17:
21. Using Valve Housing Bearing Remover MIT213039 and Handle MB990938-01, drive the bearing and seal from the valve housing (Fig. 17).
22. Remove the teflon seals from the spool valve and the rack. NOTE: The old seals can be cut off with a razor blade or sharp knife.
23. Clean all parts thoroughly. NOTE: Now is a good time to discard all bearings, seals, Orings, and teflon rings removed from the gear to avoid the possibility of mixing-up old and new parts.
B. INSPECTION
24. Inspect the rack.
a. Check tooth face for wear.
b. Check the oil seal contact surface for damage.
c. Check to see the rack is straight.
25. Inspect the pinion.
a. Check condition of the pinion gear teeth.
b. Check the oil seal contact surface for wear.
26. Inspect the rack housing.
a. Check for damage, nicks, especially in the oil seal area, etc.
27. Inspect the bellows boots on the tie rods. If they are cracked or deteriorated or have holes or cracks in them, replace them.
C. ASSEMBLY
28. Open the seal kit and remove the four teflon rings that will be used on the spool valve.
29. Heat up the rings in a cup of hot water ( > 130 degrees F.) Slip Piston Seal Expander MIT307100 over the end of the spool valve. Then slip on the first of the teflon rings. Compress the teflon ring into the groove with your fingers. Then, remove the installing tool and slide Pinion Seal Sizer MIT213046 over the seal carefully to compress it into the groove.
30. Repeat the process, adding a spacer MIT213042 or MIT213047 before each successive ring until all four are installed.
FIGURE 21:
31. Remove the larger teflon ring from the kit, heat it in the cup of hot water, and install it on the rack, using tool MIT213044 (Fig. 21): slide the heated ring over the tool as you did with the spool valve. Again, compress the ring into the groove by hand before using the sizing tool MIT213045
32. Clamp the rack housing in the holding fixture and slip one of the new seals over special tool MB213049 which is attached to handle MB990928-01. Then lubricate the outer rim of the seal with multipurpose grease, and install the seal into the rack housing.
NOTE: The green teflon ring on the seal goes toward the inside of the bore; the spring in the seal should be visible after the tool is removed.
33. Using the same tool, install the second of the two seals on the end housing. Replace the O-ring on the end housing with a new one from the kit.
34. Remove the rack housing from the holding fixture and put it on a clean, smooth flat surface such as the anvil of your bench vise.
35. Pack the new pinion shaft bearings with multipurpose grease, and using special tool MIT307101 on Handle MB990938-01, install the pinion shaft lower bearing into the housing.
36. Now, slip Pinion Shaft Upper Bearing Seal Installer MIT213049 over Handle MB990938-01 and then put the pinion shaft upper bearing seal on the tool. Lubricate the outside surface of the seal, and push the seal into the housing.
37. Lubricate the new pinion shaft upper bearing with multipurpose grease. Then, with tool MIT307101 on handle MB990938-01, install the pinion shaft upper bearing into the housing.
38. Slip the rack seal protector MIT213064 (long, clear plastic sleeve) onto the rack, and insert the rack into the housing through the seal. Remove the rack seal protector.
39. Lubricate the pinion gear with multipurpose grease and insert it into the housing so that the pinion engages with the rack. Use a brass or aluminum drift if needed to drive the pinion shaft into place.
40. Install a new O-ring in the recess around the spool valve.
FIGURE 31:
41. Obtain the new valve housing upper bearing MB243364 and seal MB243363 or MB350598 from Kit MB243343 and install them one after the other onto the valve housing, using tool MIT213041 and handle MB990938-01 (Fig. 31).
NOTE: the spring side of the seal goes toward the inside of the housing.
42. Lubricate the bore of the valve housing with Power Steering Fluid, and carefully slip the valve housing over the spool valve, taking great care not to damage the teflon rings in the valve. Install the attaching screws and torque them to 14-22 ft.lbs.
43. Hand-tighten the self-locking nut on the end of the pinion shaft. NOTE: Hold the pinion shaft with the Stub Shaft Holding Tool MIT213043 and a 3/8" handle while tightening the nut to 14-22 ft.lbs.
44. Apply semi-drying sealant (Permatex) to the threads of the plug, screw the plug into the housing, and tighten it to 36-51 ft.lbs. Stake the plug in two places.
45. Install the rack support, spring, and rack support cover. Tighten the rack support cover to 5-10 ft.lbs and then back off 30-60 degrees (1 flat maximum on the special tool). Using the stub shaft holding tool and an inchpound torque wrench, turn the stub shaft at a slow, steady rate from one extreme of travel to the other, watching the torque required to turn the shaft, The turning torque should be between 5 and 11 in.lb. throughout the travel. If not, tighten or loosen the rack support cover. When you are sure the turning torque is within the specified range, install the locknut and tighten to 36-51 ft.lbs.
46. Install a new O-ring on the rack housing.
47. Lubricate the teflon ring on the rack with power steering fluid, and install the cylinder assembly. Be sure the notch in the cylinder indexes with the pin in the housing.
48. Hand-tighten the cylinder nut and tighten it with spanner MIT307098 to 66-99 ft.lbs. (This is the actual reading of the torque wrench attached to the spanner). Stake the nut in place.
49. Slip the short rack seal protector MIT213040 over the end of the rack that protrudes from the cylinder.
50. Lubricate the inner diameter of the seal in the end housing and slip the end housing over the rack. Screw the end housing into the cylinder by hand. Then tighten it with Wrench MIT213038 to 58-72 ft.lbs.
51. Install the tie rod ends and nuts on the ends of the pinion shaft. NOTE: Hold the pinion shaft with the Stub Shaft Holding Tool MIT213043 and a 3/8" handle while tightening the nut to 14-22 ft.lbs.
52. Secure the nuts by staking the tab washers with a hammer.
53. Install the new O-rings on both sides of the banjo fitting on the long Seal And Feed Tube Assembly (Fig. 40A), and also install a new O-ring on the flared end of the assembly (Fig. 40B).
54. Install new O-rings on the shorter external tube.
55. Install the shorter feed tube first, then the longer one.
56. Install a new O-ring on the return tube and screw the return tube onto the valve housing. Before tightening the flare nut, orient the tube.
57. Remove the gear assembly from the holding fixture and reinstall it on the vehicle.