CHAPTER 3 TABLE OF CONTENTS CHAPTER/SECTION PAGE OVERHAUL I. RECOMMENDED OVERHAUL PERIODS 3-1 1 A. GENERAL... 1 B. HYDRAULIC PUMP... 1 C. DISC BRAKE CALIPERS... 1 D. BRAKE BOOSTER PUMP... 1 E. MASTER CYLINDER... 1 F. PLANETARY REDUCTION HUBS... 1 II. STEER AXLE 3-2 1 A. DISCUSSION... 1 B. INSPECTION AND OVERHAUL... 1 III. HYDRAULIC PUMP 3-3 1 A. DISCUSSION... 1 B. HYDRAULIC (STEERING) PUMP ASSEMBLY REMOVAL:... 1 C. HYDRAULIC (STEERING) PUMP ASSEMBLY INSTALLATION:... 1 IV. MASTER CYLINDER DISASSEMBLY AND ASSEMBLY 3-4 1 A. MASTER CYLINDER REMOVAL... 1 B. DISASSEMBLY... 1 C. INSPECTION AND REPAIR... 2 D. ASSEMBLY... 2 Chapter 3: Overhaul Sept. 1995 p. 1
IV. MASTER CYLINDER DISASSEMBLY AND ASSEMBLY 3-4 1 E. BLEEDING THE MASTER CYLINDER... 3 F. MASTER CYLINDER INSTALLATION... 3 V. FOUR WHEEL DISC BRAKES 3-5 1 A. BRAKE PAD REPLACEMENT... 1 1. Preparation:... 1 2. Rear Caliper Removal... 1 3. Brake Pad Removal... 2 4. Cleaning and inspection:... 2 5. Brake Pad Installation... 4 6. Caliper Installation... 4 7. Check-Out:... 5 B. CALIPER OVERHAUL... 6 1. General Layout; Front... 6 2. Removal... 6 3. Disassembly... 7 4. Cleaning and Inspection... 8 5. Reassembly... 8 6. Installation... 9 7. Check-Out:... 9 C. FRONT ROTOR... 9 1. Rotor Removal... 9 2. Cleaning... 10 3. Inspection... 10 4. Reassembly... 10 5. Installation... 10 6. Check Out... 10 D. BLEEDING THE DISC BRAKE SYSTEM... 11 1. General... 11 2. Manual Bleeding... 11 3. Pressure Bleeding... 11 4. Check-Out... 12 E. REAR WHEEL DISK BRAKE SPECIFICS... 12 1. Caliper Removal... 12 2. Rear Caliper Assembly... 13 Chapter 3: Contents Sept. 1995 p. 2
I. Recommended Overhaul Periods A. GENERAL The following overhaul periods are approximate and can vary greatly due to different operating conditions. Units operating in extreme conditions such as high or low temperatures, long periods of sustained operation, continued operation in sand or dust or continued exposure to sea air or moisture require careful, regular inspections. Overhaul periods may be adjusted with time and experience in operating this tractor. If an overhaul of a component or system is anticipated or required, the procedures that cover that component or system should be read and fully understood prior to attempting any part of the overhaul. B. HYDRAULIC PUMP Overhaul when internal or external leakage is evident or after 5,000 hours. C. DISC BRAKE CALIPERS Calipers should be overhauled if piston seizure is evident, if leakage occurs around piston boot or if uneven braking persists after troubleshooting brake lines. D. BRAKE BOOSTER PUMP Booster pump components (i.e. pump section and motor section) can be replaced more easily and economically than overhauling. Refer to troubleshooting section to isolate brake booster problems. E. MASTER CYLINDER Refer to troubleshooting section to isolate problems with master cylinder. Master cylinder should be rebuilt if piston gasket damage is evident and when significant brake pressure is being lost after all other possible causes have been eliminated. F. PLANETARY REDUCTION HUBS Hubs should pass roll test and leak test before being deemed service worthy. Refer to Final Drives supplement, chapter 5. Chapter 3: Overhaul Sept. 1995 Section 3-1 p. 1
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II. STEER AXLE A. DISCUSSION If tractor has been properly lubricated and maintained and has not experienced damage to the steering system, the steering components will provide many hours of service without an overhaul. Should overhaul be required, follow the procedure below: WARNING: OBSERVE ALL SAFETY PRECAUTIONS DISCUSSED IN THE SAFETY SEC- TION OF THIS MANUAL! B. INSPECTION AND OVERHAUL Jack up the front end of the tractor using normal jacking procedures (i.e., chock rear tires, apply hand brake, and place blocks under tractor front bumper). Inspect the steering linkage rod for damage. Also check for wear of the linkage rod ball joints by grasping the rod and shaking it. If the linkage rod ball joints are loose, replace the rod. 1. Bearings and Seals Grasp the top and bottom of each tire and shake it in and out while observing the hub and spindle area to detect any wobble or looseness. If any wobble or looseness is noted in the hub and the spindle is rigid, the wheel bearings and seals should be adjusted by tightening the hub retainer nut. If excessive noise is experienced after adjustment, the bearings and seals should be replaced as follows: (c) (d) (e) (f) Remove the front wheels by removing the lug nuts on each wheel. Remove disc brake caliper. Remove the grease cap, cotter pin, outer hub retainer nut, nut lock and inner hub retainer nut. Grasp the hub and slide it off the axle shaft. Remove the inner and outer seals and bearings from the hub and wipe the hub interior clean. Inspect hub interior surfaces (bearing races) for scoring. If the races are scored or worn, replace with new races. (g) Install new bearings and seals into the hub, packing the bearings with lithium-based grease, and replace the hub onto the axle shaft. (h) (i) (j) Replace caliper. Secure the hub with the retainer nuts and nut lock and replace the hub cap. Install the wheel. Chapter 3: Overhaul Sept. 1995 Section 3-2 p. 1
II. STEER AXLE B. INSPECTION AND OVERHAUL (CONT): 2. A-Arm Bushings Removal/Replacement: Note: This procedure written with the assumption that both sets of bushings to be changed. Spindle assemblies do not have to be removed for this procedure, however a-arms will be quite heavy. Procedure is written as if spindles are to be left intact on a-arms. a. Chock rear tires, jack front end of vehicle. Secure front with jackstands under front frame. b. Remove tires. c. Remove tie rod. Note: Use jack stands, floor jacks or individual jack stands to support a-arms before disconnecting tie rod. d. Remove calipers: (1) Remove upper king pin cover (two bolts). (2) Unbolt and tie-off calipers. e. Remove lower shock bolt. Note: This bolt also holds bottom link of spring limiter chains. f. Remove (2) main a-arm pivot bolts. Remove a-arm assembly. g. Remove old bushings; press-in new bushings. Note that bushings are located at the tips of the U-shape. The span between the U- tips must be bridged so that arms are not bent during pressing. Rig a secure steel bridge between the arms, or contact Tug Manufacturing regarding special tooling. h. Reassemble a-arm(s) but do not tighten pivot bolts. i. Rotate a-arm into place, attach bottom shock bolt with chain limiter. Tighten securely. j. Tighten a-arm pivot bolts securely. k. Reassemble remaining components in reverse order from disassembly. 3. Tie Rod Ends: Grasp the sides of the wheel and shake it from side to side while observing the rod ends. If excessive movement is observed in the rod connection ends, replace the connecting rod ends as follows: Chapter 3: Overhaul Sept. 1995 Section 3-2 p. 2
(c) Disconnect the rod ends from the spindle arms, removing the cotter pins and retainer nuts. Remove the connecting rod and remove the rod end retainer clamps. Screw the new rod ends approximately 1/4 inch into each end of the rod. (d) (e) (f) Install the connecting rod to the spindle arms, securing the connecting rod ends to the spindle arms with the two (2) retainer nuts and cotter pins. With the wheels pointing straight forward, adjust the toe-in by turning the connecting rod until the centerline-to-centerline distance across the back of the tires is 0 to 1/8 inch longer than the centerline-to-centerline distance across the front of the tires. After the toe-in adjustment has been accomplished, install the rod end clamps, securing the connecting rod adjustment. Chapter 3: Overhaul Sept. 1995 Section 3-2 p. 3
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III. HYDRAULIC PUMP A. DISCUSSION Hydraulic pump should be overhauled after 5000 hours or when internal or external leakage is evident. The hydraulic pump assembly can be divided into three main components. (Refer to figure on page 2). Reservoir, pump section & motor. Disassemble and replace all worn or damaged parts. B. HYDRAULIC (STEERING) PUMP ASSEMBLY REMOVAL: CAUTION! SIDE PANELS ARE HEAVY! REMOVE CAREFULLY 1. Disconnect battery, remove right side access panel. 2. Disconnect electrical wiring. 3. Remove (4) mounting bolts: Use long extension rachet and matching wrenches below tractor. CAUTION: WIPE ALL CONNECTIONS CLEAN PRIOR TO OPENING SYSTEM. CAUTION: CAP OR PLUG ALL OPEN PORTS AND LINES. NOTE: USE BACK UP WRENCHES ON ALL MATING FITTINGS. 4. Gently rotate pump to reveal access to hydraulic line connections. 5. Use tape to label lines (in & out). 6. Remove hydraulic lines at elbows. 7. Remove pump & reservoir assembly. C. HYDRAULIC (STEERING) PUMP ASSEMBLY INSTALLATION: 1. Place pump & reservoir assembly into floor of right side service bin, reservoir end toward rear of vehicle. 2. Attach hydraulic lines at elbows. 3. Attach assembly to floor using (4) mounting bolts: Use long extension rachet and matching wrenches below tractor. 4. Connect electrical wiring. 5. Top off hydraulic fluid in reservoir. 6. Replace right side access panel. Chapter 3: Overhaul Sept. 1995 Section 3-3 p. 1
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Ref. Part Description No. No. No. Req'd 1 03142 PUMP ASSEMBLY, Gear Code 62 1 02625 PUMP ASSEMBLY, Gear Code 51 1 02650 PUMP ASSEMBlY, Gear Code 43 1 02624 PUMP ASSEMBlY, Gear Code 42 1 02629 PUMP ASSEMBLY, Gear Code 05 1 02659 PUMP ASSEMBLY, Gear Code 03 1 2. 02352 O-RING, Industrial (3-5/8 x 3-7/8 x 1/8) 1 3. 00075 PARTS KIT, Check Valve (main) 1 4. 02159 SEAL 1 5. 03766 PARTS KIT, Relief Valve 1 6. 03427 SWITCH, Solenoid, 12 VDC, 3-post grounded to can 1 03481 SWITCH, Solenoid, 12 VDC 3-post (coated) grounded to can 1 03336 SWITCH, Solenoid, 12 VDC, 3-post insulated ground 1 03340 SWITCH, Solenoid, 12 VDC, 3-post (coated) insulated ground 1 03335 SWITCH, Solenoid, 12 VDC 4-post isolated ground 1 03342 SWITCH, Solenoid, 12 VDC 4-post (coated) isolated ground 1 03467 SWITCH, Solenoid, 24 VDC, 3 post, grounded to can 1 03652 SWITCH, Solenoid, 24 VDC, 3 post, (coated) grounded to can 1 03343 SWITCH, Solenoid, 24 VDC 3 post insulated ground 1 03344 SWITCH, Solenoid, 24 VDC 3 post (coated) insulated ground 1 7. 01349 STRAP, Motor-Solenoid 1 8. 07683 SCREW, Round Head Machine 10-32 x 1/4 2 9. 08111 MOTOR, Electric, 12 VDC 1 08112 MOTOR, Electric, 12 VDC 1 08120 MOTOR, Electric, 24 VDC 1 10. 02318 BEARING, Base, motor 1 11. 07625 NUT, Hex 5/16-24 1 12. 07781 WASHER, Lock 5/16" 1 13. 07737 WASHER, Star 1/4" 4 14. 07795 WASHER, Lock 1/4" 2 15. 07738 SCREW, Hex Head Cap 1/4-20 x 6-1/2" 2 16. 02238 BRACKET, Mounting 1 17. 04559 BRACKET, Plate Mount 5.00" C to C 1 04560 BRACKET, Plate Mount 3.25" C to C 1 18. 07894 Socket Head Cap, Thread forming, torx drive, 5/16-18 x 1-1/8 2 19. 07717 SCREW, Hex Head, thread forming 1/4-20 x 1-3/8 2 20. 01134 SCREEN, Filter (suction) 1 21. 01209 TUBE, Filter Suction 3/8 NPT 90 Deg. 1 22. 01329 ADAPTER, Pump Mounting Bracket 1 23. 01274 TUBE, Return (1/8 NPT) 1 24. 06661 RESERVOIR, 4-1/2" Dia. x 8", 76 cu in usable 1 06663 RESERVOIR, 4-1/2" Dia. x 10", 102 cu in usable 1 06665 RESERVOIR, 4-1/2" Dia. x 12", 127 cu in usable 1 25. 06678 RESERVOIR, 5" x 5" x 10", 211 cu in usable1 06663 RESERVOIR, 5" x 5" x 12", 249 cu in usable 1 06665 RESERVOlR, 5" x 5" x 15", 306 cu in usable1 26. 01143 PLUG, Vent (plastic) 1 03866 PLUG, Vent, 3/8" NPT 1 27. 01482 TUBE ASSEMBLY, Downspout, return (1/4 NPT Mx F) 1 28. 07703 SCREW, Thread Forming 10-24 x 3/8" 6 Chapter 3: Overhaul Sept. 1995 Section 3-3 p. 3
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IV. MASTER CYLINDER DISASSEMBLY AND ASSEMBLY A. MASTER CYLINDER REMOVAL 1. Open Console door. 2. Remove brake lines from cylinder body. 3. Plug brake line ports or drain brake fluid into appropriate container. 4. Remove (2) mounting bolts and nuts. 5. Slide master cylinder off of push rod. When it is necessary to repair the master cylinder during the warranty period, replace the cylinder as a unit instead of overhauling the cylinder with a service repair kit. B. DISASSEMBLY 1. Clean the outside of the master cylinder and remove the reservoir cover and reservoir diaphragm. Drain any fluid left in the cylinder. Be careful with brake fluid as it damages painted surfaces. Chapter 3: Overhaul Sept. 1995 Section 3-4 p. 1
IV. MASTER CYLINDER DISASSEMBLY AND ASSEMBLY B. DISASSEMBLY(CONT) 2. Remove the push rod boot (if equipped), from the groove at the rear of the master cylinder, and slide the boot away from the rear of the master cylinder. 3. Remove the snap ring holding the pistons in the cylinder body. 4. Remove the push rod (if equipped), and primary piston assembly from the master cylinder. Discard the piston assembly, including the boot (if equipped). WARNING: USE LOW AIR PRESSURE TO REMOVE THE PISTON. HIGH PRESSURE COULD RESULT IN DAMAGE OR PERSONAL INJURY. 5. Using an air hose in the rear brake outlet port of the cylinder body, carefully blow the secondary piston out of the cylinder body. Remove the return spring, spring retainer, cup protector and cups from the secondary piston. Discard the cup protector and cups. C. INSPECTION AND REPAIR 1. Clean all parts in clean isopropyl alcohol or Rotunda Brake Parts Washer (model 650016) or equivalent, and inspect the parts for chipping, excessive wear or damage. Replace them, if necessary. When using a master cylinder repair kit, use all the parts provided. 2. Check all recesses, openings and internal passages to be sure they are open and free of foreign matter. 3. Inspect the hydraulic master cylinder bore for etching, pitting or rust. Replace the master cylinder if any of these conditions exist. D. ASSEMBLY 1. Remove the master cylinder from the vise. Check the outlet ports for brass burrs and remove, if present. 2. Dip all the parts except for the cylinder body in clean ESA-M6C25-B extra heavy duty brake fluid or equivalent and lubricate the bore walls with brake fluid. 3. Assemble the secondary cup and 0-ring back-to-back in the grooves near the end of the secondary piston. Assemble the cup protector, primary cup, spring retainer and secondary piston return spring on the other end of the secondary piston. 4. Install the secondary piston assembly in the master cylinder. Wet the seals with the brake fluid and use caution when inserting the piston assemblies into the bore to prevent damage to the seals. Chapter 3: Overhaul Sept. 1995 Section 3-4 p. 2
5. Install the primary piston assembly in the master cylinder. Push the primary piston inward and tighten the secondary piston stop bolt to hold the secondary piston in the bore. 6. Position the stop plate and snap ring on the primary piston. Depress the primary piston and install the snap ring in the cylinder body. 7. Bleed the master cylinder. E. BLEEDING THE MASTER CYLINDER Before installing the master cylinder on the vehicle, bleed the unit as follows: 1. Support the master cylinder body in a soft-jawed vise and fill both fluid reservoirs with ESA-M6C25-A extra heavy duty brake fluid or equivalent. 2. Install plugs in the front and rear brake outlet ports. Bleed the rear brake system first. 3. Loosen the plug in the rear brake outlet port. Depress the primary piston slowly to force the air out of the master cylinder. Tighten plug while piston is depressed to prevent air from entering the master cylinder. 4. Repeat this procedure until air ceases to exit at the outlet port. 5. Repeat steps (3) and (4) for the front brake outlet port with the rear brake outlet plugged. 6. Tighten the plugs and attempt to depress the piston. The piston will resist depression after all air is expelled. 7. Install the cover and diaphragm assembly, being sure the cover retainer is tightened securely. Remove the plugs. F. MASTER CYLINDER INSTALLATION 1. Open Console door. 2. Slide master cylinder onto push rod. 3. Mount cylinder body using (2) mounting bolts and nuts. 4. Unplug cylinder brake line ports. 5. Attach brake lines to brake line ports. Chapter 3: Overhaul Sept. 1995 Section 3-4 p. 3
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V. FOUR WHEEL DISC BRAKES The following illustrations and procedures apply specifically to the M3 front disc brakes. To accomodate the specific requirements of the specialized rear end, a different brake caliper has been designed into the M3 rear disk brakes. In general, the following procedures can be applied to the rear brakes as well. For specific rear brake information, refer to section E at the end of this section. A. BRAKE PAD REPLACEMENT Inspect the brake linings any time that the wheels are removed. Check both ends of the outboard pad by looking in at each end of the caliper. These are the points at which the highest rate of wear normally occurs. However, at the same time, check the lining thickness of the inboard pad to make sure that it has not worn prematurely. Look down through the inspection hole in the caliper to view the inboard pad. Whenever the thickness of any lining is worn to the approximate thickness of the metal backing, all pads on the axle should be replaced. 1. Preparation: For front service, chock rear wheels and raise front of vehicle. For rear service, chock front tires and raise rear. 2. Front Caliper Removal (c) Remove 2/3 of brake fluid from master cylinder reservoir. Push the piston back into its bore. This can be accomplished by using a C-clamp. Using 3/8" allen wrench, loosen and remove (2) mounting (retainer) bolts (see figure 1). Lift the caliper off the rotor and position on drive axle so that the brake hose will not support the weight of the caliper. Figure 1 Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 1
V. FOUR WHEEL DISC BRAKES A. BRAKE PAD REPLACEMENT 2. Caliper Removal (cont.): (d) (e) NOTE: If only brake pads and linings are being replaced, omit step (d). Disconnect brake line from caliper and plug openings in caliper and line to prevent fluid loss and to keep out contamination. (See Figure 2.) Inspect mounting bolts for corrosion. If corrosion is found, use new bolts when installing caliper. 3. Brake Pad Removal Remove the inboard pad and spring from piston. Dislodge the outboard pad and remove from caliper. Remove sleeves from mounting bolt holes and discard. Remove the four rubber bushings from the grooves in each of the caliper ears and discard. (See Figure 3.) 4. Cleaning and inspection: Figure 2 Examine the piston area for fluid leaks by looking for excessive moisture around boot area. Check dust boot for cracks, cuts or other damage that would affect its ability to seal piston bore. If leaks are present or boot shows damage, the caliper should be overhauled. See specific section. If no defects are found, wipe clean the inside of the caliper including the four ears where bushings are to be installed. Wipe the outside surface of the dust boot so that when piston is pressed to bottom of bore, boot will fold back without coming out of groove. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 2
Figure 3: Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 3
V. FOUR WHEEL DISC BRAKES A. BRAKE PAD REPLACEMENT (CONT.): 5. Brake Pad Installation (c) (d) (e) Using Delco Silicone Lube No. 179-651, lubricate new sleeves, new rubber bushings, and bushing grooves. Install rubber bushings in all four caliper ears. Note: It is essential that the new sleeves and rubber bushings which are included in each Delco pad kit be used, and that lubrication instructions be followed to insure proper functioning of the sliding caliper design. Use Delco Tool, J-22835, to install the sleeve. Position the sleeves so that the end toward the pad is flush with the machined surface of the ear. Attach pad retainer clip to inboard pad lining so that spring vee is on inner arc of pad. Install inboard pad and lining as shown. (See Figure 4.) Position outer arc of pad against inner arc of caliper. Depress spring vee to collapse it and enable it to slip inside of piston cup. Snap pad into place. Figure 4 Clip outer pad into place opposite inner pad. Make sure that the tab at the bottom of the pad is engaged in the caliper cut-out. 6. Caliper Installation Position caliper over rotor and line up holes in caliper ears with holes in the mounting bracket. Make sure the brake hose is not twisted or kinked. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 4
Lubricate both ends of the mounting bolts with Delco Silicone Lube No. 179-651. Start the bolts through the sleeves in the inboard caliper ears and mounting bracket, making sure that the ends of the bolts pass under the retaining ears of the inboard pad. Push the bolts through to engage the bushings in the outboard caliper ears, while threading the bolts into the mounting bracket. Tighten bolts. (See Figure 5.) (c) (d) (e) (f) (g) 7. Check-Out: Figure 5 Torque bolts to 40.7-61.0 N-m (30-45 ft.-lbs.) Remove temporary plugs from brake pipe and fittings, connect brake pipe to caliper. Torque to 20 N-m (15 ft.-lbs.). If brass bolt and block were removed with brake pipe, unplug fittings and install bolt and block using (2) new copper washers. Torque to 40 N-m (30 ft.-lbs.). Fill master cylinder and bleed hydraulic system. After installing caliper, set caliper by applying heavy force to brake pedal. Check brake pedal for sponginess or hard pedal. Drive vehicle slowly and make several slow speed stops. (c) (d) Check all brake fluid line fittings and caliper areas for fluid leakage. Correct any discrepancies before returning vehicle to service. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 5
V. FOUR WHEEL DISC BRAKES B. CALIPER OVERHAUL 1. General Layout; Front Figure 6 2. Removal Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 6
See Pad Replacement Section. Removal of the caliper for overhaul is the same as for Pad replacement except that it will be necessary to disconnect the brake hose. 3. Disassembly Move the caliper to a work bench for overhaul. (c) (d) (e) (f) (g) (h) Drain fluid from caliper. Remove pad and spring clip from end of piston. Before beginning caliper disassembly, thoroughly clean exterior using denatured alcohol. Support caliper in a vise and pad caliper interior with shop cloths. Use a piece of 1x 6 soft pine to prevent piston from coming out completely (See figure 7). Use just enough compressed air in caliper brake line port to force piston out. Excessive air may cause piston to be blown out of bore and become damaged. Warning! Use of compressed air without wood block may result in damage to the piston and/or personal injury. Figure 7 Remove wood block. Gently work piston the rest of the way out of bore. Use a screwdriver to pry boot out of caliper as shown. Use care to avoid scratching the caliper bore (See Figure 8). (i) (j) Remove piston seal from caliper bore. Use a piece of wood or plastic (a wooden toothpick is ideal) so as not to damage caliper bore. Remove bleed valve. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 7
V. FOUR WHEEL DISC BRAKES B. CALIPER OVERHAUL (CONT.): 4. Cleaning and Inspection Figure 8 Thoroughly clean all parts not in repair kit with denatured alcohol. Inspect caliper bore for scoring, nicks, corrosion or wear. Use crocus cloth to polish out any light corrosion. Replace caliper housing if bore will not clean up using crocus cloth. Carefully examine the piston exterior for scoring, nicks, corrosion and worn or damaged surfaces. If any surface defects are detected, replace the piston. CAUTION: THE PISTON OUTER SURFACE IS THE PRIMARY SEALING SURFACE IN THE CALIPER ASSEMBLY. IT IS MANUFACTURED AND PLATED TO CLOSE TOLERANCE. REFINISHING BY ANY MEANS, OR THE USE OF ANY ABRASIVE IN THE FIELD IS NOT ACCEPTABLE. 5. Reassembly Lubricate piston assembly with clean brake fluid. (c) Position the seal in the caliper bore groove. Assemble a new boot into the piston groove so that the fold faces the open end of the piston. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 8
(d) (e) Press piston assembly into caliper bore using C-clamp (See figure 9). Be careful not to unseat the seal. Position outside diameter of boot in caliper counterbore and seat with Delco tool no. J-22904. 6. Installation Figure 9 Install caliper following instructions given in Pad and Lining Replacement Section. Bleed system. 7. Check-Out: (c) (d) C. FRONT ROTOR 1. Rotor Removal Check brake pedal for sponginess or hard pedal. Drive vehicle slowly and make several slow speed stops. Check all brake fluid line fittings and caliper areas for fluid leakage. Correct any discrepancies before returning vehicle to service. Rotor Removal (1) Chock the rear tires. Jack the front wheels off the ground. (2) Inspect the lug nuts which secure the wheel to the drive axle hub and remove. (3) Remove the cotter pin from the hub nut and remove the nut and washer. (4) Remove caliper assemblies. See specific section. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 9
V. FOUR WHEEL DISC BRAKES C. FRONT ROTOR 2. Cleaning (5) Slide the wheel hub and rotor off the axle. (6) Press rotor from hub. WARNING: NO SMOKING, FIRE OR OPEN FLAME IS PERMITTED IN AREAS WHERE ALCOHOL IS BEING USED. AVOID INHALATION OF FUMES. 3. Inspection (c) Clean rotor with alcohol. Use lint-free cloth to dry. Inspect weldments (rear only) for evidence of corrosion or cracking. Replace if cracked or severely corroded. Inspect rubbing surfaces for evidence of corrosion, pitted or scratches. Replace if scratched, corroded or pitted. Check the thickness and out of plane limits of the rotor. The minimum limit should be.885 inches (front). 4. Reassembly: Press hub onto lugs. 5. Installation (c) (d) Slide the wheel hub and rotor onto the axle. Replace caliper assemblies. See Specific Section. Replace axle nut and washer and replace cotter pin. Seal with silicone sealer. Replace wheel and secure with lug nuts. (e) Lower front wheels to the ground and un-chock rear wheels. 6. Check Out Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 10
(c) (d) Check brake pedal for sponginess or hard pedal. Drive belt loader slowly and make several slow speed stops. Check all brake fluid line fittings and caliper areas for fluid leakage. Correct any discrepancies before returning vehicle to normal service. D. BLEEDING THE DISC BRAKE SYSTEM 1. General (c) 2. Manual Bleeding If the caliper was removed for overhaul, or if the brake hose or steel line was disconnected for any other reason, it will be necessary to bleed all air from the calipers and connecting lines. Prior to bleeding the system, it is important to check the master cylinder reservoir. Use hydraulic fluid, DOT 3, Extra Heavy Duty Brake Fluid to bring the level up to within one-eighth (1/8) inch of the top. Brakes can be bled either manually or with pressure bleeding equipment. CAUTION: FLUID WHICH IS DRAINED, FLUSHED OR BLED OUT OF A VEHICLE S BRAKE SYSTEM SHOULD BE DISCARDED. IS NOT SAFE FOR REUSE FOR ANY PURPOSE. Manual bleeding requires two people; one to pump the brake pedal and another to operate the bleeder valves. Make sure that the master cylinder is full. After the bleeder valve is opened, depress the brake pedal one full stroke, close bleeder valve, then allow the pedal to return slowly to the released position. Allowing the pedal to return too quickly may draw air into the system. Continue operating the pedal in this manner until caliper is bled. Refill the master cylinder and go on to next caliper. CAUTION IN ORDER TO INSURE THAT NO AIR CAN BE SUCKED BACK INTO THE SYSTEM, THE BLEEDER VALVE MUST BE CLOSED A THE END OF EACH STROKE, BEFORE THE BRAKE PEDAL IS RELEASED. Check the fluid level in the reservoir frequently during the bleeding procedure. 3. Pressure Bleeding If the equipment is available, the pressure bleeding is faster, since the master cylinder does not have to be refilled several times. Pressure bleeding equipment must be of the diaphragm type. That is, it must have a rubber diaphragm between Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 11
V. FOUR WHEEL DISC BRAKES D. BLEEDING THE DISC BRAKE SYSTEM 3. Pressure Bleeding (cont.): the air supply and the brake fluid to prevent air, moisture, oil and other contaminants from entering the hydraulic system. Install the special bleeding adapter to the master cylinder. Make sure that the pressure tank is at least 1/3 full of fluid. 4. Check-Out (c) (d) Position the tank so that its hose will easily reach the adapter on master cylinder of the vehicle being serviced, then make the air pressure connection to the tank (20 to 25 psi). Open the tank valve to bleed all air out of the hose before connecting it to the adapter. After making this connection, open the valve when ready to begin bleeding. CAUTION: DO NOT LIFT, MOVE OR SHAKE THE TANK AFTER AIR PRESSURE IS APPLIED. THIS MAY CAUSE AIR TO BECOME TRAPPED IN THE FLUID. Bleed front calipers. NOTE: Pressure bleeding process may be completed more quickly by lightly tapping the brake pedal when the bleeder valve is opened. This creates pulsations that tend to purge air from the system. Check brake pedal for sponginess or hard pedal. Drive vehicle slowly and make several slow speed stops. Check all brake fluid line fittings and caliper areas for fluid leakage. Correct any discrepancies before returning vehicle to normal service. E. REAR WHEEL DISC BRAKE SPECIFICS 1. Caliper Removal Jack rear of tractor, remove tire. Remove (2) caliper mounting bolts. (c) Slide caliper off top of rotor. Note: Pad replacement can be accomodated at this point without further disassembly. If further caliper service is required, refer to section A-2-(d) regarding handling of brake lines and fluid. Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 12
2. Rear Caliper Assembly See Figure 10 (below). Figure 10: Rear Caliper Exploded Assembly Chapter 3: Overhaul Sept. 1995 Section 3-5 p. 13
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