Manual Rack & Pinion Service

Fig. 3 Components of rack & pinion steering gear:

Disassembly

Before disassembling, measure starting torque in neutral (center) position using torque wrench and suitable socket for reference during reassembly.
1. Remove tie rod assembly as follows:
a. Remove bellows band, then the bellows.
b. Unstake tie rod with chisel, then remove left side ball joint.
c. Move rack fully to right, then remove left tie rod.
d. Remove right tie rod by repeating steps a through c. Never reuse a removed tie rod.
2. Remove locknut from yoke plug, then yoke plug using tool No. MB990607-A, or equivalent.
3. Remove yoke spring, cushion rubber and support yoke from gear housing.
4. Remove oil seal and snap ring, then pinion with bearing.
5. Remove bearing retainer snap ring from pinion, then bearing using tool No. MB990783, or equivalent.
6. Remove rack from gear housing.

Assembly

1. Press bearing onto pinion using tool No. MB990783 or equivalent, then install snap ring.
2. Apply multipurpose grease to rack, pinion, bushing, needle bearing and all other sliding surfaces. Do not seal off air passage in housing with grease.
3. After installing rack into gear housing, install pinion in mesh with rack.
4. Select and install appropriate snap ring to minimize axial play of pinion. Snap rings are available in thicknesses of 0.063, 0.066 and 0.069 inch.
5. Apply grease to oil seal lips, then install into gear housing.
6. Apply grease to dented portion of support yoke and sealer to yoke plug, then install support yoke, cushion rubber, yoke spring and plug into gear housing. Adjust yoke plug with rack in neutral position using tool No. MB990607-A or equivalent and torque to 5-11 ft. lbs., then back off 30-60°. Secure yoke plug with locknut, then torque locknut to 36-51 ft. lbs.
7. Install tie rod assembly as follows:
a. After tightening tie rod to rack to 58-72 ft. lbs., secure by staking rack keyway with punch.
b. Install bellow to gear housing, then secure with band. Tie rod side clip band should be installed after adjustment of toe-in.
c. Measure full rack stroke (lock to lock). The stroke should be 5.43 inches (138 mm). Refer to image for standard dimensions of tie rod and rack and pinion assembly. The full stroke of rack determines maximum steering angle.
d. Torque tie rod locknuts to 36-40 ft. lbs. (49-54 Nm).
8. Preload of pinion should be measured by turning pinion at rate of a revolution every 4 to 6 seconds using tool No. MB990228. Preload should be 3.6-9.6 in. lbs. (.4-1.1 Nm). The rack starting force should be 11-66 lbs. If measured values are not within specifications, replace cushion rubber and yoke spring and readjust as in step 6. Pinion preload should be measured over full stroke of rack.