Manual Transmission/Transaxle: Description and Operation

Gearbox F380

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 automatic interior mirror - if fitted; the mirror moving to the dimming position.

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.

OPERATION

Drive is transmitted from the crankshaft, through the clutch to the gearbox input shaft which transmits drive via the layshaft to the output shaft in all gears with the exception of 4th gear which provides a direct drive from the input shaft to the output shaft. Drive from the gearbox output shaft is transmitted to the transfer box input shaft via a flange splined to the output shaft.