Clutches GMC Pickup R2500

DESCRIPTION

The hydraulic clutch consists of a driven plate, pressure plate, a diaphragm-type spring, and a release bearing.

The hydraulic clutch has a master cylinder with a separate reservoir. The clutch pedal moves master cylinder push rod and a secondary cylinder at the clutch housing moves clutch fork and release bearing.

TRANSMISSION APPLICATION

BLEEDING HYDRAULIC CLUTCH SYSTEM

Note. Never use fluid which has been used or bled from the system to fill reservoir.

1. Fill reservoir with clean DOT 3 brake fluid. Disconnect slave cylinder from bellhousing, leaving line attached. Hold slave cylinder at a 45 degree angle with bleeder screw facing up.
2. Have an assistant depress clutch pedal while you open bleeder. Close bleeder and release pedal. Repeat sequence until all air is removed from system. Make sure master cylinder reservoir stays full during bleeding process.

CHECKING HYDRAULIC CLUTCH SYSTEM

Check hoses for cracks, wear or other damage. Check hydraulic cylinders for loose mounting and signs of leakage. Clutch pedal travel should be at least 8" (203 mm). Secondary push rod travel, at clutch fork, should be at least 1" (25 mm). If necessary, bleed hydraulic system.

Removal ("C", "K", "R" & "V" Series)

1. Disconnect negative battery cable. On 2WD models, remove shift lever boot attaching screws and slide boot up shift lever. Place transmission in Neutral and remove lever.
2. On 4WD models, remove center console, shift boot, boot bridge, and selector switch. On all models, raise and support vehicle. On 4WD models, remove skid plate and disconnect vacuum harness.
3. Remove drive shaft(s). Disconnect speedometer cable and wiring from transmission. Remove clutch slave cylinder. Support transmission and remove transmission mount bolts.
4. Remove exhaust pipes, crossmember and any other components needed for clearance. Remove dust cover bolts. Remove transmission mount bolts. Carefully remove transmission and transfer case (if equipped).

Installation

To install, reverse removal procedure. Lightly coat input shaft splines with high temperature grease.

Removal ("M, "S" & "T" Series)

1. Disconnect negative battery cable. Remove shift lever boot. Shift transmission in Neutral. Disconnect shift control rods (if equipped). Remove shift lever.
2. Raise and support vehicle. Remove brake cable for clearance. Mark drive shaft for reassembly reference. Remove drive shaft.
3. Disconnect speedometer cable and wiring from transmission. Disconnect exhaust pipe. Support transmission. Remove support braces and skid plate (if equipped). Remove other components, as needed, for clearance.
4. Remove clutch slave cylinder from transmission. Remove crossmember. Remove bolts holding transmission to engine. Remove transmission from vehicle.

1. To install, reverse removal procedure. Lightly coat input shaft splines with high temperature grease to aid in reassembly.
2. Shift transmission into high gear. Install support braces. Tighten braces to clutch housing before tightening to transmission. Install new seal on speedometer cable. Adjust shift linkage. Add transmission lubricant.

Removal

1. Remove transmission. Remove slave cylinder from bellhousing. Remove screws and flywheel cover. Remove bellhousing. Remove clutch fork and release bearing. Remove ball stud or clutch fork retainer if worn or damaged.
2. Install clutch pilot in clutch disc during removal. Mark flywheel, clutch cover, and pressure plate lug for reassembly reference. Evenly loosen clutch bolts one or 2 turns at a time until clutch plate spring tension is released. Remove clutch pilot, clutch cover, and disc.

1. Support clutch disc and pressure plate on flywheel with clutch pilot. Make sure index marks on pressure plate and flywheel are aligned. Tighten bolts evenly and in sequence to avoid distortion.
2. Remove pilot. Lubricate ball stud and fork fingers with high temperature grease. Lubricate O.D. groove and pack grease into I.D. recess of release bearing.
3. If clutch fork retainer is being replaced, install retainer so that fingers and tabs fit into release bearing groove and retainer wraps around flat side of ball stud. Reverse removal procedure to complete installation.

Clutch Assembly & Pilot Bearing Borg Warner 77 MM transmission is shown. Scheme 1

1. Disconnect negative battery cable. Remove steering column covers or panel. On "C", "K", and "S" series, remove A/C duct from lower left side of instrument panel.
2. On all models, disconnect push rod from clutch pedal. Disconnect reservoir hose at master cylinder. Remove master cylinder retaining nuts. Remove master cylinder.

To install, reverse removal procedure. Bleed system. Refer to BLEEDING HYDRAULIC CLUTCH SYSTEM .

Scheme 2

Removal & Installation

Raise and support vehicle. Disconnect and cap the hydraulic line at the slave cylinder. Remove the slave cylinder. To install slave cylinder, reverse removal procedure. Bleed hydraulic system. Refer to BLEEDING HYDRAULIC CLUTCH SYSTEM .

Scheme 3

Disassembly & Inspection

1. Pull back rubber dust cover and remove snap ring from cylinder. Extract push rod. Shake out plunger and spring assembly. Pull out reservoir (adapter) and seal. (Scheme 2)
2. Remove spring from nose of plunger. Remove seal support, front seal, and shim from plunger. Be careful not to damage plunger surface. Clean all parts with clean brake fluid.
3. Make sure cylinder bore is smooth to touch. Inspect bore for visible ridges or scores. Master cylinder must be replaced if scored or damaged.

Reassembly

1. Lubricate seals and cylinder bore with clean brake fluid. Fit back seal into groove in plunger. Install front seal on plunger with flat side against shim. Install seal support and spring.
2. Carefully install plunger assembly into bore. Depress plunger with push rod and seat snap ring in groove. Lightly grease inside of dust boot and install. Put reservoir seal into master cylinder and press reservoir into place.

1. Remove push rod and rubber dust cover. Remove retaining snap ring. Shake plunger and spring assembly out of the cylinder. Carefully remove the seal from the plunger. DO NOT damage plunger surface. (Scheme 3)
2. Clean all parts in clean brake fluid. Inspect cylinder bore for ridges or scratches. Bore must be smooth to touch. Replace cylinder if bore does not pass inspection.

Place seal in groove on plunger. Lubricate bore and seal with clean brake fluid. Slide spring and plunger assembly into cylinder bore. Depress plunger far enough to install snap ring in groove. Lightly grease inside of dust boot and install boot. Install push rod.

ADJUSTMENTS

The hydraulic clutch system is nonadjustable.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

See also:
• BLEEDING HYDRAULIC CLUTCH SYSTEM