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R380
1
DESCRIPTION AND OPERATION MANUAL TRANSMISSION
Description
The all synchromesh five speed manual gearbox unit,
is married to a LT230T two speed transfer gearbox.
All the gears including reverse run on needle roller
bearings and the main, layshaft and primary shafts
are supported by tapered roller bearings.The whole of the geartrain is lubricated through
drillings in the shafts, supplied by a low pressure
pump driven from the rear of the layshaft. The gear
change has a single rail selector and spool type
interlock. The main and transfer gearboxes ventilate
through nylon pipes, which terminate high up in the
engine compartment to prevent water entry when the
vehicle is operating in adverse conditions.
1. Mainshaft 1st gear
2. Mainshaft 2nd gear
3. Mainshaft 3rd gear
4. Primary input shaft
5. Mainshaft 5th gear
6. Layshaft
7. Mainshaft
8. Lubrication pump9. Drain plug
10. Ventilation pipe
11. Single rail gear shift
12. 1st/2nd synchromesh
13. Oil seals
14. 3rd/4th synchromesh
15. 5th gear synchromesh
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R380
1
FAULT DIAGNOSIS MANUAL GEARBOX
Symptom - Gear jumps out of engagement (any
forward gear)
1.Check condition and security of transmission
and engine mountings.
2.Check in situ, gear lever and selector
adjustments.
3.In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4.Check action/operation of main selector rail and
forks.
5.Check condition of synchromesh and gear dog
teeth.
6.Check main and layshaft end floats bearings and
adjustments.
7.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Reverse gear only jumps out of
engagment
1.Check condition and security of transmission
and engine mountings.
2.Check in situ, gear lever and selector
adjustments.
3.In situ, remove gearshift and check selector rail
yoke security.
Also check selector detent spring tension and
both spool retainers.
Suspect internal fault
See remove and overhaul procedure.
4.Check action/operation of main selector rail and
reverse lever.
5.Check condition of reverse gear, angled
bearings and shaft.
6.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.Symptom - Excessive force required to engage or
change gear, vehicle stationary or moving.
1.Check lubricant specification and level, if low do
not top up at this stage.
2.In situ, lubricate gear mechanism, and check
selector adjustments.
3.In situ, remove gearshift and check selector rail
is free and that the yoke is secure. Also check
selector detent spring tension and both spool
retainers.
4.Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh unit or baulk rings
on affected gears. See remove and overhaul
procedure.
Symptom - Noisy gear engagement, vehicle
stationary.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults
Symptom - Noisy gear selection, vehicle moving.
1.Confirm that clutch operation is satisfactory.
2.Establish which gear/gears is causing noise.
3.Check lubricant specification and level, if low do
not top up at this stage.
4.Drain lubricant and check for contamination or
metal particles.
Suspect worn synchromesh. See remove and
overhaul procedure.
5.Check condition of synchromesh unit, springs
and cones for distortion and wear. Also check
dog teeth for damage and cone mating surface
on gear for signs of overheating.
6.Check condition of all gearbox components,
ensure clearances and adjustments are correct
on reassembly.
Symptom - Noise from gearbox in neutral, which
changes tone or becomes worse when clutch is
depressed.
See CLUTCH, Fault diagnosis, Clutch
Noise - Mechanical Faults
Page 403 of 976

R380
1
REPAIR R380 MANUAL GEARBOX
Service repair no - 37.20.02
Remove
WARNING: Where the use of a
transmission hoist is necessary, it is
absolutely essential to follow the
manufacturer's instructions to ensure safe and
effective use of equipment.
1.Install vehicle on a ramp [hoist].
2.Disconnect battery earth lead.
3.Remove centre console.
See CHASSIS AND
BODY, Repair, Centre Console
4.Remove sound insulation from top of
transmission tunnel.
5.Remove bolt and remove upper gear lever.
6.Remove screws securing gear selector lever and
high/low selector lever draft excluders.
7.Remove draft excluder clamp rings.
8.Remove handbrake cable clevis pin clip and
clevis pin.
9.Remove 'C' clip and cable adjuster.
10.Select low range to prevent gear lever fouling
tunnel when removing gearbox.
11.Remove bolt securing gearbox breather pipe clip
to cylinder block.
12.Remove bolts securing fan cowl to radiator.
13.Release fan cowl from radiator and lay over fan
blades.
14.Raise ramp [hoist].
15.Drain oil from main gearbox and transfer
gearbox.
See SECTION 10, Maintenance,
Under Vehicle Maintenance
16.Remove exhaust front pipe(s).See MANIFOLD
AND EXHAUST SYSTEM, Repair, Exhaust
System Complete
17.Release intermediate exhaust pipe(s) from
mountings and tie aside.
18.Remove bolts securing clutch slave cylinder.
19.Release slave cylinder from clutch housing and
collect spacer.
20.Mark propeller shaft drive flange relationships for
reassembly.
21.Disconnect front and rear propeller shafts from
transfer gearbox. Tie shafts aside.
22.Remove clamp and disconnect speedometer
cable from transfer gearbox.
23.Release handbrake cable from transmission
tunnel.
24.Temporarily support transmission in a way which
enables the crossmember to be removed and a
hoist cradle to be fitted.
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37MANUAL GEARBOX
2
REPAIR 25.Remove nuts and bolts securing transmission
cross-member to chassis.
26.Remove nuts and bolts securing cross-member
mountings to transmission.
27.Remove cross-member.
28.Manufacture an adapter plate to dimensions
given in service tool section and attach it to a
transmission hoist. To achieve balance of the
transmission unit when mounted to hoist, it is
essential that pointA,is situated over lifting hoist
ram. Drill holesBto suit hoist table. Secure the
transmission unit cradle at pointCusing the
lower bolts retaining transfer gearbox rear cover.
Raise hoist just enough to take weight of
transmission.
29.Lower hoist sufficiently to allow transfer gearbox
selector lever to clear transmission tunnel
aperture.
30.Disconnect differential lock switch connectors.
31.Disconnect reverse lamp switch connectors.
32.Remove clips securing gearbox breather pipes
to harness.
33.Support engine under sump with a jack.
CAUTION: Use a wooden block to protect
sump.
34.Remove bell housing nuts.
35.Withdraw transmission whilst ensuring all
connections to engine and chassis are released.36.Remove transmission assembly from hoist
cradle and position safely on a bench.
37.Remove breather pipes. Discard pipe union
sealing washers.
38.Remove 'Nyloc' nut, and remove bolt, securing
lever to high/low shaft.
39.Collect spacer washer.
40.Remove 2 clips and remove differential lock
lever link.
41.Remove lower locknut from high/low operating
rod.
42.Place a sling round transfer box and attach to
hoist.
43.Remove nut and 5 bolts securing transfer
gearbox to extension housing.
44.Withdraw transfer gearbox.