Renewing The Gearbox Extension Oil Seal; Refitting The Gearbox - MG MGA Twin Cam Workshop Manual

Fit the layshaft and thrust washers. Line up the cutaway portion of the front end with the layshaft
locating groove in the front cover.
Fit the reverse gear and shaft; tighten and lock the Set Screw.
Refit the front end cover, replacing the bearing shims that were removed on dismantling. Refit the
clutch lever and fork. Fit the selectors to the shifter shaft rear ends. Bolt the shifter shaft locating block
to the rear face of the gearbox; replace the balls and springs and insert the shifter shafts.
Position the gear change forks in the box in the following sequence: reverse, first and second, third
and top. Push the shifter shafts into the box and through the forks; insert, tighten, and wire up the set
screws.
Position the selectors on the rear ends of the shifter shafts; insert, tighten, and wire up the set screws.
Refit the gearbox rear extension. Locate the change speed gate in the gearbox and fit the side cover,
using a new joint as necessary.
Screw in the speedometer drive gear assembly, plugs and breather.
The remote control assembly is fitted to the gearbox, and the gearbox filled with oil, after the power
unit is installed in the chassis.
F.9 RENEWING THE GEARBOX EXTENSION OIL SEAL
Remove the four bolts securing the propeller shaft front universal joint to the gearbox flange.
Hold the flange steady with Service tool 18G34A and remove the nut and spring washer.
Remove the flange.
Using Service tool 18G389 with adaptor 18G389B, withdraw the old seal.
Use Service tool 18G134 with adaptor 18G134N to fit the new seal.
Refit the flange, nut, and spring washer
F.10 REFITTING THE GEARBOX FRONT COVER
To prevent oil leaking past the gearbox front cover oil seal the cover must be correctly fitted to ensure
that the seal is concentric with the first motion shaft. When refitting the cover proceed as follows.
Clean off the cover and examine it carefully for burrs and bruising, particularly around the bore, stud
holes, and machined surfaces. Check the flat surfaces for twist and warp and correct it if necessary. If
the condition is too bad to correct, fit a new cover.
Remove and discard the front cover to gearbox gasket and clean off the flat surfaces around the base
of all studs.
Offer the front cover (less oil seal) to the gearbox and push it fully home on the studs. The cover
should be free to move in all directions, and points at which the holes may be binding on the studs
must be relieved until the cover is free to float.
Remove the cover and, using Service tool 18G134 with adaptor 18G134N, fit the oil seal so that its lip
faces inwards towards the gearbox. Lightly grease and fit a new gasket to the gearbox front face, then
fit the centralizer (Service tool 18G598) to the bore of the front cover and push it in until it is tight.
Lightly oil the seal and pass the cover over the first motion shaft, taking particular care not to cut or
damage the knife edge of the sea).
Keep the centralizer firmly in position, push the cover onto the studs, and fit the spring washers and
nuts, tightening the nuts finger-tight only. Use a suitable socket spanner and long extension to tighten
the nuts a half-turn at a time by diametrical selection until all nuts are fully tightened.
Remove the centralizer and refit the clutch operating components.
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