Specifications, Service and Repair of Farm and Lawn Tractors


Laycock and Rockford clutch for Case IH Tractor 385/485/585/685

Tractor models may be equipped with a Laycock pressure plate assembly and an 11 inch (279 mm) single plate dry disc engine clutch plate.

Tractor models may be equipped with a Rockford pressure plate assembly and a 12 inch (305 mm) single plate dry disc engine clutch plate.

On tractor models not equipped with cab, all tractors have mechanical clutch operating linkage. On models equipped with cab, engine clutch is hydraulically operated.

Case IH Tractor Adjustment

Models Without Cab

PEDAL HEIGHT. Clutch linkage is identical on all models Case IH 385/485/585/685 tractor without a cab. However, adjustment dimensions for Laycock clutch 11 inch (279 mm) differs from dimensions for Rockford clutch 12 inch (305 mm).

To adjust the clutch linkage, loosen locknut (2), Remove return spring and clevis pin.

Adjust clevis (3) on rod until the following dimensions are obtained with clevis connected:

Laycock Clutch

C. Free travel - 1-1/4 in. (32 mm)
E. Full travel - 4-17/32 in. (115 mm)
D - 6-5/16 in. (160 mm)

Rockford Clutch

C. Free travel - 1/2 in.(12.7mm)
E. Full travel - 4-21/32 in.(118mm)
D - 7-1/16 in.(179 mm)

Reconnect return spring and tighten locknut. Loosen locknut and adjust safety start switch (5) until there is a clearance between safety start switch and clutch pedal of 9/32 inch (7 mm). Tighten locknut.

Models With Cab

PEDAL HEIGHT. To adjust the clutch pedal height on models with cab, disconnect line from master cylinder. Unbolt master cylinder and loosen lock-nut (1) on push rod (4). Loosen locknut on stop bolt (2), then turn stop bolt counterclockwise several turns.

Raise master cylinder and rotate push rod with fingers as required. Install master cylinder and tighten retaining bolts. Measure distance from floor pan (mat removed) to pedal.

Fig.8. Engine clutch pedal height adjustment on models equipped with cab

Distance should be 7-7/8 to 8-1/8 inch (199 to 205 mm). If not, readjust push rod to obtain correct dimension. Then, tighten locknut on push rod. Turn stop bolt (2) until it contacts clutch pedal, turn bolt clockwise an additional 1/4 turn and tighten locknut.

Check safety start switch position. Loosen locknut and turn switch in or out as required so that switch button is pushed inward when clutch pedal is fully depressed.

Tighten locknut. Reconnect lines to master cylinder. Fill reservoir and bleed air from.

Case IH Tractor Clutch cylinders

To remove clutch master cylinder, first disconnect battery ground cable. Then, press inward on lock pins and remove instrument panel front cover.

RRemove screws from both sides of instrument panel, raise and support instrument panel. Disconnect pedal return spring. Place a container under instrument panel to catch the fluid.

Disconnect lines from Case IH 385/485/585/685 tractor master cylinder. Unbolt master cylinder from bracket and raise the cylinder. Loosen locknut and turn push rod counterclockwise from the clevis. Lift out master cylinder.

To disassemble the master cylinder, first remove locknut from push rod (7), Remove rubber boot (10), snap ring (9), retaining washer (8) and push rod (7). Remove plunger and spring assembly from cylinder housing (1).

Remove seals (2 and 6) from plunger assembly. Clean and inspect all parts. A service kit consisting of seal (1), wave washer (4), seal (6), retaining washer (8), snap ring (9) and rubber boot (10) is available.

If plunger or cylinder housing shows signs of scoring or other damage, renew cylinder assembly. Reassemble and reinstall by reversing disassembly and removal procedures. Bleed air from system. Adjust pedal height.

To remove clutch slave cylinder, remove floor mat and inspection panel from floor. Disconnect hose from slave cylinder. Remove linkage return spring. Remove the two snap rings and linkage pin. Unbolt and remove slave cylinder.

To disassemble the slave cylinder, remove eye clevis (7). Remove rubber boot (6) and snap ring (5), then withdraw piston (4) with seal (3). Remove seal from piston.

Clean and inspect piston and cylinder housing (2) for scoring or other damage. If scored or damaged, renew cylinder assembly. A service kit consisting of bleed screw rubber cap (1), seal (3), snap ring (5) and rubber boot (6) is available.

Reassemble and reinstall by reversing the disassembly and removal procedures. When installing eye clevis (7) on piston (4), apply Loctite 270 to first three threads of piston rod.

Adjust eye clevis so that a distance of 3.4 inches (86.0 mm) is obtained between centers of cylinder mounting holes and eye clevis hole (with piston fully inward). Bleed air from system.

Fig.9. Clutch master cylinder used on models equipped with cab

1.Housing, 2.Seal, 3.Valve stem, 4.Wave washer, 5.Plunger, 6.Seal, 7.Push rod, 8.Retaining washer, 9.Snap ring, 10.Rubber boot

Fig.10. Clutch slave cylinder used on models equipped with cab

1.Bleed screw cap, 2.Housing, 3.Seal, 4.Piston, 5.Snap ring, 6.Rubber boot, 7.Eye clevis

Bleed Clutch System

To bleed air from system, remove bleed screw cap (1) and connect a length of transparent hose with its free end in Hy-Tran Plus fluid. Loosen bleed screw.

Fill reservoir with Hy-Tran Plus MS 1207 fluid to maximum level mark. Fully press and release clutch pedal. Repeat as required until fluid free of air bubbles flows through the hose. Then, tighten bleed screw while holding pedal down.

Make certain that fluid level In reservoir Is kept above minimum level mark during bleeding operation. Remove bleed hose and refill reservoir with fluid.

Overhaul Clutch

Fig.12. 11 Inch (279 mm) Laycock clutch. Four pad clutch disc and Six pad clutch disc

1.four pad clutch disc, 1A.six pad clutch disc, 2.Pressure plate, 3.Cover, 4.Spring cup, 5.Cup, 6.Finger, 7.Spring clip, 8.Cap screw, 9.Nut, 10.Wear clip, 11.Pin

To remove engine clutch, it is first necessary to detach (split) engine from clutch housing as follows: Disconnect battery cables and remove battery. Remove hood, grille and side panels. Disconnect tachometer cable, starter wiring and rear wiring connector. Shut off fuel and disconnect supply line and fuel return line.

Cap all openings. Disconnect injection pump speed control and shut off cables. Identify and disconnect oil cooler lines and steering lines and cap all openings. On tractors so equipped, disconnect heater hoses and air conditioning lines.

On Case IH 385/485/585/685 tractor equipped with front drive axle, remove drive shaft shield and front drive shaft. If available, attach a split stand under clutch housing and engine oil pan or block up under clutch housing and attach a hoist to engine.

Place wood blocks between front axle and front support to prevent tipping. Unbolt clutch housing from engine and move front half of tractor forward.

Fig.11. 12 Inch (305 mm) Rockford clutch

1.Clutch disc, 2.Pressure plate, 3.Spring seat, 4.Insulating washer, 5.Spring, 6.Spring cup, 7.Cover, 8.Finger, 9.Cap screw, 10.Washer, 11.Finger tension spring, 12.Pin

Unbolt and remove pressure plate assembly and remove clutch friction disc. Inspect the friction disc and if pads are worn to a point where there is less than 0.010 inch (0.24 mm) of material above rivet heads, renew the disc.

Inspect pressure plate for grooving and flatness. If plate is grooved more than 0.025 inch (0.64 mm) or if face is worn out-of-flat more than 0.006 inch (0,152 mm), renew pressure plate. Do not reface a worn pressure plate.

When reinstalling, reverse removal procedure. Clutch friction disc is marked FLYWHEEL SIDE for correct installation. Adjust clutch pedal height.