MANUAL GEARBOX - R380 (Description): DESCRIPTION AND OPERATION

MANUAL GEARBOX - R380

DESCRIPTION AND OPERATION

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Description

General
The R380 all synchromesh gearbox has five forward speeds and reverse and is mounted in line with the engine. The 
clutch bell housing  is bolted to the front of the gearbox and the transfer box is mounted at the rear.

Gearbox casings
Gearbox casings consist of a front cover, gearcase, centre plate and extension housing. All casings with the exception 
of the front cover are located to each other by dowels and sealed. Gearbox filler/level and drain plugs are located in 
the gearcase. 

Reverse lamp switch
 A reverse lamp switch is inserted into the extension housing. Selection of reverse gear will close the switch allowing 
current from fuse 25 to flow through the switch to illuminate the reverse lamps. The switch also provides a feed to the 
BCU and the electrochromic automatic interior mirror - if fitted; the mirror moving from the dimmed position if 
applicable.

Gearchange assembly
The gearchange assembly is bolted to the top of the gearcase, the upper gear lever being attached to the lower gear 
lever by means of a clamp bolt. The lower gear lever ball is housed in a Railko bush inserted in the gear change 
housing, the end of the lever locating in the selector yoke which is attached to the end of the selector shaft. Bias 
springs provide a positive return of the gear lever to the neutral position with selection of 1st/2nd and 5th/reverse gears 
being against bias spring pressure. Spring loaded detent balls fitted in the centre plate locate in grooves in the selector 
shaft to provide positive gear and neutral selection.

Lubrication
Lubrication is by an oil pump located in the extension housing and driven by the layshaft with additional lubrication 
being provided by splash. The pump directs oil via a filter and internal drillings in the output shaft to lubricate the 
components. On non UK and non European models, provision for oil cooling is by means of a thermostat housed in 
a cover bolted to the side of the extension housing. The cover incorporates tappings for connections to an oil cooler. 
On UK and European models, the thermostat and cover are replaced by an oil by-pass block.

Internal pressures produced within the gearbox are vented to atmosphere via a plastic breather pipe. The pipe is 
attached to the extension housing and is routed across the top of the gearcase and secured at the open end by a clip 
attached to the engine cylinder block.

Selector shaft and forks
Selector forks for 1st/2nd, 3rd/4th and 5th/reverse gears are located on a single selector shaft; the 1st/2nd and 3rd/
4th selector forks are inside the main gearcase whilst the 5th/reverse selector fork is inside the extension housing. 
Each of the selector forks locates inside its corresponding synchromesh hub.

Synchromesh assemblies
Each synchromesh assembly is located on the output shaft adjacent to its corresponding gears and comprises a 
synchromesh ring, hub, slippers and sleeve. The hubs and slippers are retained in the sleeves by means of spring 
clips. 1st/2nd and 3rd synchromesh assemblies are fitted with double synchromesh rings whilst 4th, 5th and reverse 
assemblies are fitted with single rings.

The gear train
The gear train comprises an input shaft, output shaft, layshaft and reverse idler shaft together with their appropriate 
gears and synchromesh assemblies.

The gear train input shaft, output shaft and layshaft are supported by taper roller bearings with all gears on the input 
and output shafts running on caged needle roller bearings. Layshaft gears are integral with the shaft with the 
exception of reverse/5th gears which are splined to the shaft and retained with a nut. 1st, 2nd, 3rd and 4th gears are 
shot peened to improve durability. The reverse idler shaft and gear are supported in the centre plate by a caged 
needle roller bearing. End-float of the output shaft and layshaft is controlled by selective shims located in the centre 
plate whilst reverse idler shaft end-float is controlled by a selective shim located behind reverse gear.