POWER ASSISTED SYSTEM (POWER STEERING) > Steering Gearbox
1. BASIC INSPECTION
1. Clean all disassembled parts, and check for wear, damage, or any other faults, then repair or replace as necessary.
2. When disassembling, check the inside of gearbox assembly for water. If any water is found, carefully check the boot for damage, input shaft dust seal, adjusting screw and boot clips for poor sealing. If faulty, replace with new parts.
(1) Bend of input shaft
(2) Damage on serration
If the bend or damage is excessive, replace the entire gearbox assembly.
(1) Crack or damage
If the outer wall slips, the lip is worn out or damage is found, replace it with a new one.
Rack and pinion
Poor mating of rack with pinion
(1) Adjust the backlash properly.
By measuring the turning torque of gearbox and sliding resistance of rack, check if rack and pinion engage uniformly and smoothly with each other. (Refer to “Service limit”.)
(2) Keeping the rack pulled out all the way so that all teeth emerge, check teeth for damage.
Even if abnormality is found in either (1) or (2), replace the entire gearbox assembly.
(1) Bend of rack shaft
(2) Bend of cylinder portion
(3) Crack or damage on cast iron portion
Replace the gearbox assembly with a new one.
(4) Wear or damage on rack bush
If the free play of rack shaft in radial direction is out of the specified range, replace the gearbox assembly with a new one. (Refer to “Service limit”.)
(5) Wear on input shaft bearing
If the free plays of input shaft in radial and axial directions are out of the specified ranges, replace the gearbox assembly with a new one. (Refer to “Service limit”.)
Crack, damage or deterioration
(1) Looseness of ball joint
(2) Bend of tie-rod
Damage or deterioration on dust seal
Adjusting screw spring
(1) Damage to flared surface
(2) Damage to flare nut
(3) Damage to pipe
2. SERVICE LIMIT
Make a measurement as follows. If it exceeds the specified service limit, adjust or replace.
When making a measurement, vise the gearbox assembly by using ST. Never vise the gearbox by inserting aluminum plates, etc. between vise and gearbox assembly.
Sliding resistance of rack shaft:
400 N (41 kgf, 90 lb) or less
3. RACK SHAFT PLAY IN RADIAL DIRECTION
0.19 mm (0.0075 in) or less
L: 5 mm (0.20 in)
P: 122.6 N (12.5 kgf, 27.6 lb)
0.3 mm (0.012 in) or less
0.15 mm (0.0059 in) or less
L: 5 mm (0.20 in)
P: 98 N (10 kgf, 22 lb)
4. INPUT SHAFT PLAY
In radial direction
0.18 mm (0.0071 in) or less
P: 98 N (10 kgf, 22 lb)
In axial direction
0.5 mm (0.020 in) or less
P: 20 - 49 N (2 - 5 kgf, 4 - 11 lb)
5. TURNING RESISTANCE OF GEARBOX
Using the ST, measure the gearbox turning resistance.
Maximum allowable resistance:
Less than 9.33 N (0.95 kgf, 2.10 lb)
Difference between right and left sliding resistance:
Less than 20%
6. OIL LEAKING
1. If the leak is found, it is necessary to thoroughly remove the fluid from the suspected portion and turn the steering wheel from lock to lock about thirty to forty times with engine running, then make comparison of the portion immediately after and several hours after this operation.
2. Inspect leakage from “a”
The oil seal is damaged. Replace the valve assembly with a new one.
3. Inspect leakage from “b”
The torsion bar O-ring is damaged. Replace the valve assembly with a new one.
4. Inspect leakage from “c”
The pipe is damaged. Replace the faulty pipe or O-ring.
5. If leak is other than a, b, c and if oil is leaking from the gearbox assembly, move the right and left boots toward tie-rod end side, respectively, with the gearbox assembly mounted to the vehicle, and remove fluid from the surrounding portions. Then, turn the steering wheel from lock to lock thirty to forty times with the engine running, then make comparison of the leaked portion immediately after and several hours after this operation.
(1) Leakage from “d”
The cylinder seal is damaged. Replace the rack bush with a new one.
(2) Leakage from “e”
There are two possible causes. Take the following step first. Remove the pipe B assembly from the valve housing, and close the circuit with ST.
Turn the steering wheel from lock to lock thirty to forty times with the engine running, then make comparison of the leaked portion between immediately after and several hours after this operation.
• If leakage from “e” is noted again:
The oil seal of pinion and valve assembly is damaged. Replace the pinion and valve assembly with a new one. Or replace the oil seal and parts that are damaged during disassembly with new ones.
• If oil stops leaking from “e”:
The oil seal of rack housing is damaged. Replace the oil seal and the parts that are damaged during disassembly with new ones.
2017-02-20 18:50:38 2017-06-19 10:25:05