GEARLESS CENTRE DIFFERENTIAL

26 Hume Reserve Court, North Geelong Vic. 3215Phone:(03) 5272 2844Fax: (03) 5272 2633

DEDICATED LOW RANGEGCD

for

TOYOTA LANDCRUISERHZJ 75/78/79

INSTALLATION MANUAL

FULL-TIME 4X4 TRANSFER CASE CONVERSION

PTY. LTD. ABN 30 079 688 181

GEARINGYNAMICSD

S e e o u r w e b s i t ew w w. g e a r i n g d y n a m i c s . c o m

E m a i l : s e r v i c e @ g e a r i n g d y n a m i c s . c o m

DEDICATED LOW RANGE GCD

THIS SEQUENCE APPLIES ONLY TO MANUAL/MECHANICAL TYPE TRANSFER CASE.

NOTE: Transfer case does not need to be removed from the vehicle for GCD installation.

1. REMOVE FRONT AND REAR PROP SHAFTS

2. MEASURE TRANSFER TURNING TORQUEWith the gearbox in neutral and transfer in LOW, measurethe turning torque and record the result.

3. REMOVE FRONT AND REAR COMPANION FLANGES.(a) Using hammer and chisel release staked part of nut.(b) Using SST hold the companion flange whilst removing lock nut.(c) Remove the companion flange from shaft.

4. REMOVE THE DRIVE SHIFT LEVER AND DUST BOOT.

5. REMOVE 4WD INDICATOR LIGHT SWITCH.Re-use as oil plug. Switch will not be needed with vehicle in constant 4WD.

NOTE: The wires can be bridged to provide the dash indicator light.

6. REMOVE THE PLUGS, SPRINGS AND LOCKING BALLS.(Mechanical shift type only)Replace the screw plug only. Other items not required with GCD.

7. REMOVE SPEEDO DRIVEN GEAR AND CABLE.

8. REMOVE POWER TAKE-OFF COVER.This allows access to the transfer case bolts.

9. REMOVE REAR OUTPUT SHAFT REAR BEARING RETAINER.(a) Remove and retain speedo drive gear.(b) Spacer is NOT required with GCD.

10. REMOVE IDLER GEAR SHAFT LOCK PLATE.

11. REMOVE TRANSFER REAR CASE. (a) Remove the bolts(b) Using a plastic hammer split and remove the transfer case half.

NOTE: Use extreme caution in splitting the case, keeping the split even so that the case does not jam. The separation is helped by tapping the idler shaft in.

12. REMOVE REAR OUTPUT SHAFT ASSEMBLY. Remove shift fork and shaft and slide out assembly.Shift fork and shaft are not needed with GCD.

NOTE: Gear box must be in neutral.

13. REMOVE IDLER SHAFT O-RING.

14. REMOVE REAR OUTPUT SHAFT FRONT BEARING RETAINER.

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PTY. LTD. ABN 30 079 688 181

GEARINGYNAMICSD

DISASSEMBLY PROCEDURE

DISASSEMBLY

15. REMOVE CLUTCH SLEEVE WITH SHIFT FORK AND SHAFT.Discard these parts as they are not needed with the GCD.

16. REMOVE FRONT OUTPUT SHAFT.A new shaft is supplied with the GCD.

NOTE: If the transfer case is new or near new the bearing and seal need not be disturbed.

17. REMOVE TRANSFER HIGH AND LOW SHIFT OUTER AND INNER LEVER.Discard these parts.

NOTE: A WELSH PLUG is provided in the KIT to block off the shaft hole.

18. REPLACE REAR OUTPUT SHAFT FRONT BEARING OUTER RACE.A new cup is supplied in GCD KIT No. 30209.

19. REPLACE REAR OUTPUT SHAFT REAR BEARING OUTER RACE.A new cup is supplied in GCD KIT No. 32010X.

Install the ORIGINAL shim into the rear bearing retainer.

NOTE: A 75 series low range GCD can be installedinto a 78 series transfer case by replacingthe 78 series idler gear with a 75 seriesidler gear.

LOW RANGE OUTPUT GEAR75 SERIES 38 TEETH78 SERIES 41 TEETH

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ASSEMBLY

1. REPLACE FRONT OUTPUT SHAFT OIL SEAL.(Only if necessary).

2. REPLACE THE FRONT OUTPUT SHAFT BEARING.(Only if necessary)(a) Remove the oil seal.(b) Using a screwdriver, remove the snap ring.

3. INSTALL NEW GCD FRONT OUTPUT SHAFT.Using a plastic hammer, drive in the front output shaftuntil the flange, nut and washer can be started.Pull shaft through with the nut. Remove the nut priorinstalling companion flange.

4. REPLACE FRONT DRIVE SHIFT FORK OIL SEAL WITH 35MM WELSH PLUG. Supplied in GCD KIT.

5. REPLACE TRANSMISSION REAR OIL SEAL.(Only if necessary)Apply MP grease to the oil seal.

6. REPLACE REAR OUTPUT SHAFT OIL SEAL.(Only if necessary)Apply MP grease to the seal lip.

7. REPLACE HIGH AND LOW GEAR SELECT OIL SEAL WITH 13MM WELSH PLUG Supplied in the GCD KIT for this purpose.

8. REPLACE SPEEDOMETER DRIVEN GEAR OIL SEAL.(Only if necessary)Oil seal depth: 20mm (0.79 in).

NOTE: A pre-assembly of the transfer case is necessary to set theoutput shaft preload correctly.

9. INSTALL REAR OUTPUT SHAFT FRONT BEARINGRETAINER WITH NEW BEARING CUP IN PLACE.

10. INSTALL INTEGRAL GCD REAR OUTPUT SHAFT ASSEMBLY.

11. INSTALL TRANSFER REAR CASE.(a) Stick thrust washer onto transfer rear case with MP

grease.(b) Place new gasket on the front case.(c) Install the rear case.

12. INSTALL SPEEDOMETER DRIVE GEAR.

NOTE: Original spacer is no longer needed.

13.. ADJUSTING REAR OUTPUT SHAFTBEARING PRELOAD ( TURNING TORQUE(a) Install the new GCD bearing cup into the Speedo Drive

Bearing Retainer using the original Toyota shims.

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ASSEMBLY

ADJUSTING REAR OUTPUT SHAFT BEARING PRELOAD

14. TEMPORARILY INSTALL SPEEDO DRIVE HOUSING (a) Install the Speedo Drive Housing torquing up only 3 of the

bolts.NOTE: Align the Speedo Drive opening in the position it was

when removed ( about 7 o'clock )

(b) With the gearbox still in neutral,using a torque meter, measurethe output shaft preload or starting torque.NEW BEARING : 13-21 in.lb., 1.5-2.4 N.m.

(c) If the preload is outside these specifications remove the SpeedoDrive Housing and alter the shims under the bearing cup.

NOTE: A SHIM PACK IS PROVIDED IN THE GCD KIT FORTHIS PURPOSE

(D) When the rear output shaft preload is correctly adjusted, torqueup the 6 bolts to TORQUE: 25ft.lb, 34Nm

15. INSTALL IDLER SHAFT O-RING AND LOCK PLATE.(a) Align the shaft groove to the bolt hole.(b) Install O-ring on the shaft groove.(c) Using plastic hammer, drive in the shaft.(d) Install the lock plate and bolt.TORQUE THE BOLT: 130 kg-cm (9 ft-lb, 13N.m)

16. INSTALL FRONT AND REAR COMPANION FLANGES.(a) Install the companion flange.(b) Using SST to hold companion flange, install the

companion flange lock nut.TORQUE: (94 ft-lb, 127N.m)

(c) Stake companion flange lock nut.

17. INSTALL POWER-TAKE-OFF COVER.(a) Install the cover with gasket.(b) Apply liquid sealer to the two bolts and install and

torque as follows:TORQUE: (12 ft-lb, 17N.m)(c) Install and torque the other bolts.

TORQUE: (14 ft-lb, 19N.m)

18. INSTALL SPEEDOMETER DRIVEN GEAR.TORQUE: (9 ft-lb, 13Nm)

19. INSTALL FRONT AND REAR PROP SHAFTS.

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GCD OPERATIONAL TEST

The GCD is designed to un-lock and re-lock the common drive to front and rear axles when one axle attempts to overdrive the other axle during cornering.

NOTE: The above de-coupling action operates in both forward and reverse gears.

DE-COUPLE SIMULATION

1. With the vehicle chocked for safety at the REAR wheels raise a front axle wheel off the ground. The gearbox should be in neutral.

2. FIRST LIGHTLY rotate the PROP- SHAFT of the raised axle both clockwise and anti-clockwise.

Observation: The transfer case common axle drive should be solid and not capable of independent drive.

3. NOW FIRMLY rotate the driveshaft of the raised axle and the de-coupling can be felt as the prop-shaft breaks out and spins freely. Reverse the rotation of the raised axle prop-

shaft and the re-coupling will occur.

4. Lower the raised axle and repeat the steps to check the REAR axle.

FOR OPTIMUM PERFORMANCE

NOTE: 1. It is very important that all 4 wheels are of matching diameter for optimum traction and performance.

2. During cornering, the GCD may be heard indexing as it un-locks and re-locks. This is quite normal.

GCD KIT PARTS LIST

02 1030 (75) 1 x GCD unit comprising of case, CDA assembly and rear output02 1040 (78) shaft assembled complete with bearing cones.02 1170 1 x Front output shaft02 1220 1 x Bearing cup - 32010X02 1230 1 x Bearing cup - 3020902 1250 1 x Welsh plug - 13mm02 1260 1 x Welsh plug - 35mm02 1270 1 x Gasket -Speedo Housing- 36152-6003002 1280 1 x Gasket- Transfer Case half 36143-6002002 1210 2 x Locknuts 90179-2200502 1300 1 x Installation Manual02 1340 1 x Caution sticker

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