Section No. F.1
Section No. F.2
Section No. F.3
Removal and replacement
Section No. F.4
Section No. F.5
Dismantling the mainshaft
Section No, F.6
Section No. F.7
Fault diagnosis
Section No. F.8
Modified gears

Section F.1


The gearbox has four forward speeds and one reverse, and synchromesh is incorporated on second, third and top gears.

Top gear is a direct drive; third and second are in constant mesh; first and reverse are obtained by sliding spur pinions.

Section F.2


The gearbox oil level should be checked by the dipstick every 3,000 miles (4800 km.) and topped up if necessary.

The filler plug, which incorporates the dipstick, is located beneath a rubber cover, and is accessible when the floor mat and rubber cover have been raised.

Every 6,000 miles (9600 km.) the gearbox, and overdrive if fitted, should be drained and refilled with fresh oil.

Drain plugs are provided in the base of the gearbox and overdrive. Ensure that the drain plugs are kept clean and do not forget to replace them after draining.

The capacity of the gearbox is given in General Data.

Section F.3


  1. Turn the battery master switch, which is situated inside the luggage compartment, to the off position.
  2. Inside the car remove the seat cushions and release the clips securing the padded arm rest to the central tunnel.
  3. Unclip and roll back the carpet over the short gearbox tunnel to expose the twelve screws securing the tunnel to the body of the car. Un-screw the setscrews and remove the tunnel and its carpeting.
  4. Unscrew the six setscrews, three on either side, which secure the carpet covered bulkhead and remove the bulkhead.
  5. Using a suitable tool tap back the locking washer on the propeller shaft flange bolts and remove the bolts.
  6. Unscrew the four setpins from the gearbox mounting brackets (see Fig. A.3, Section A), also unscrew the speedometer cable at its connection to the gearbox.
    Note. – When an overdrive gearbox is fitted it will also be necessary to unclip the cable to the gearbox switch and release it at its terminal on the switch.
  7. Working beneath the vehicle remove setpins (1) Fig. A.4, Section A, and unscrew the nuts (2) and (3) to release the stabiliser bar.
  8. Detach the clutch slave cylinder from the gearbox bell housing by removing the two securing setpins. The slave cylinder push rod is released from the clutch operating lever by the removal of the securing clevis pin.
  9. Remove the starter motor as described in Section N
  10. Place suitable supports underneath the gearbox bell housing and engine sump, and unscrew the nuts, bolts and setpins securing the bell housing to the engine backplate.
  11. Withdraw the gearbox first motion shaft from the flywheel bearing and clutch by gently easing the gearbox rearwards.
    If the unit does not detach itself readily it will be necessary to raise the rear of the engine.
  12. The replacement of the gearbox is a reversal of the removal procedure. Section F.4

Section F.4


  1. Remove the dipstick. Unscrew the breather from the overdrive unit, if fitted. Drain the oil from the gearbox and overdrive by removing the drain plug beneath each unit.
  2. Unscrew the speedometer drive from the right- hand side of the rear extension.
  3. Unscrew the seven short and one long bolt and remove the clutch housing.
  4. Remove the three nuts threaded on studs mounted on the gear lever cup. With the removal of these nuts the cup may be withdrawn together with the three washers and three distance pieces located on the studs.
  5. Withdraw the gear lever from the gearbox.
  6. Unscrew the thirteen bolts securing the side cover to the gearbox housing and remove the cover; there are two dowels locating the cover. Take care not to lose the three selector balls and springs which will be released as the cover is withdrawn.
  7. Unscrew the eight bolts and remove the rear extension.
    Note. – For models fitted with overdrive.
    Once the overdrive unit has been separated from the gearbox (see Section G.10, the removal of the

Fig. F.1. Components of the Gearbox.
Fig. F.1. Components of the Gearbox.

Fig. F.1. Components of the Gearbox.
Fig. F.1. Components of the Gearbox.
  1. Synchromesh sleeve.
  2. Baulking ring.
  3. Synchronizer spring.
  4. Synchronizer ball.
  5. 3rd and 4th speed synchronizer.
  6. Baulking ring.
  7. Locking plate.
  8. Needle rollers.
  9. Third speed gear.
  10. Second speed gear.
  11. Needle rollers.
  12. Gear washer.
  13. Locking plate.
  14. Baulking ring.
  15. 2nd speed synchronizer.
  16. First speed gear.
  17. Plunger spring.
  18. Gear plunger.
  19. Main shaft.
  20. Thrust plate.
  21. Thrust washer.
  22. Needle rollers.
  23. Washer, roller.
  24. Spacer, roller.
  25. Laygear.
  26. Washer.
  27. Thrust plate.
  28. Layshaft.
  29. Interlocking balls.
  30. Selector ball and spring.
  31. Bearing nut.
  32. Bearing nut lockwasher.
  33. Bearing spring plate.
  34. Bearing plate.
  35. Bearing circlip.
  36. First motion shaft bearing.
  37. First motion shaft.
  38. Needle rollers.
  39. Joint washer.
  40. Side cover dowel.
  41. Drain plug.
  42. Gearbox casing.
  43. Bearing housing.
  44. Locating peg.
  45. Joint washer.
  46. Gear lever.
  47. Nut and washer.
  48. Cup.
  49. Rubber washer (thick).
  50. Steel washer.
  51. Rubber washer (thin).
  52. Distance piece.
  53. Side cover.
  54. Washer.
  55. Gear lever locating screw.
  56. Rubber dust covers.
  57. 1st and 2nd speed fork.
  58. Screw for fork.
  59. 3rd and 4th speed fork rod.
  60. 1st and 2nd speed fork rod.
  61. Interlocking pin and rivet.
  62. Reverse fork rod.
  63. 3rd and 4th speed fork.
  64. Reverse shaft.
  65. Bush.
  66. Reverse gear.
  67. Locking screw.
  68. Selector plunger.
  69. Selector plunger spring.
  70. Detent plunger.
  71. Detent plunger spring.
  72. Reverse fork.
  73. Controlshaft locating screw.
  74. Locking washer.
  75. Control shaft.
  76. Control lever.

adapter plate is accomplished by unscrewing the eight setpins mounted in the recess in the adapter plate.

The overdrive pump cam should slide freely along the third motion shaft thus giving access to the circlip holding the distance piece to the rear adapter plate. Remove the circlip and slide the distance piece off the shaft. The adapter plate should now pull away from the gearbox, together with the rear main bearing. It may be necessary for one operator to hold the gearbox vertically by the adapter plate whilst a second operator taps the third motion shaft until the ball race in the adapter plate is free of the shaft.

  1. Cut the locking wires and unscrew the fork retaining screws. Remove the shifter shafts and forks in.the following order :–
  1. The reverse shaft and fork together with its selector and detent plungers and springs.
  2. Top gear shifter shaft only.
  3. First and second shaft and fork.
  4. Top gear fork.

Take care not to lose the two interlock balls, normally located one at each side of the centre shifter shaft, which will be released when the shaft is removed.

  1. Unscrew the reverse shaft locating screw and push out the shaft; lift the gear from the box.
  2. Tap out the layshaft and allow the gear to rest in the bottom of the box.
  3. Withdraw the first motion shaft assembly; note that there are 16 spigot rollers.
  4. Withdraw the mainshaft rearwards.
  5. Lift out the layshaft gear and thrust washers.

Section F.5


  1. Slide the top and third gear from the forward end.
  2. Depress the plunger locating the third gear locfiag plate, rotate the plate to line up the splines and slide it from the shaft. Extract the plunger and spring, and slide off the third speed gear and its 32 rollers.
  3. Unscrew the main shaft nut; remove the nut, locking washer, speedometer drive gear, bearing with housing and distance collar.
  4. Slide the first and second speed hub, second speed interceptor and first speed gear rearwards from the shaft; if the first speed gear is withdrawn from the hub, take care to hold the balls and springs located in holes in the hub.
  5. Depress the second gear locking collar plunger and rotate the collar to line up the splines; slide the collar from the shaft and extract the two halves of the second gear washer, retaining the spring and plunger.
  6. Withdraw the second speed gear and its 33 rollers from the shaft.
  7. To dismantle the first motion shaft assembly,tap up the locking tab, unscrew the nut and remove the bearing.

NOTE.–The method of dismantling and reassembling the overdrive gearbox is the same as that described for the standard gearbox, with the exception that no speedometer drive gear or locking washer and nut is fitted.

Section F.6



  1. Smear the shaft with grease and assemble the 33 second speed gear rollers; slide the second gear into position.
  2. Replace the plunger and spring. Fit the two halves of the second gear washer and slide the collar on to the splines. Depress the plunger and push the collar into position, locating the lugs of the washer in the cut-outs of the collar; rotate the collar to bring the splines out of line.
  3. Replace the balls and springs in the second and first speed hub; depress the balls and slide the first speed gear on to the hub; refit the assembly to the shaft.
  4. Refit the bearing distance collar, the bearing and housing, the speedometer drive gear key and gear, locking washer and nut. Tighten the nut and tap over the locking washer.
  5. Fit the third gear and its 32 rollers to the shaft; replace the plunger and spring and the third speed locking plate; rotate the plate to bring the splines out of line.
  6. Fit the balls and springs to the top and third speed hub and slide the striking dog into position on the hub.
  7. Replace the hub, striking dog and interceptors on the shaft.
Fig F.2 Assembling gear and synchronizer.
Fig F.2 Assembling gear and synchronizer.
Fig F.3 Securing the third motion shaft gears.
Fig F.3 Securing the third motion shaft gears.
  1. Gear. 2. Baulking ring. 3. Synchronizer. A. Hole for spring. C . Location peg. D. Locking washer. B. Spring. E. Peg located in washer.


  1. Fit the distance tube to the layshaft gear with a washer at each end of the tube.
  2. Smear the rollers with grease and position them in the gear. Place the thrust washers and plates in position at each end of the gear.
  3. To retain the rollers in position, a length of round bar of layshaft diameter and just long enough to hold the thrust washers and plates, should be inserted in the gear assembly.
  4. Place the gear in the box and allow it to rest at the bottom.


  1. Insert the mainshaft assembly from the rear of the box.
  2. Position the first motion shaft rollers and the first motion shaft assembly in the box.
  3. Lift the layshaft gear into position, locating the thrust washer tags in the grooves provided. Push the layshaft through the housing and gear, and withdraw the retaining bar as the shaft pushes it out of the gear. The cut-away portion of the shaft must be aligned to fit the groove in the bell housing provided to prevent the layshaft from turning.
  4. Refit the reverse gear and shaft and tighten the setscrew. Place the top gear shifter fork in the box. Replace the first and second gear shifter fork and shaft.
  5. Replace one interlock ball above the first and second shifter shaft and insert the top gear shifter shaft.

  1. Position the remaining interlock ball, holding it with grease and refit the reverse fork and shaft together with its selector and detent plungers and springs.
  2. Screw in the fork setscrews, tighten up and wire.
  3. Bolt the rear extension into position, using a new gasket if necessary. Note that the plain bearing plate is fitted against the bearing.

Note. – For models fitted with overdrive :–

Slide the adapter plate, together with its bearing and paper joint washer, along the third motion shaft. Fit and tighten down the eight setpins securing the adapter plate to the gearbox.

Fit the distance piece which covers the space between the rear main bearing and the groove allocated for the circlip, and fix on the latter.

  1. Refit the selector balls to the holes in the gearbox housing and the springs in the holes in the side cover.
  2. The gear lever together with its cup, washers and distance pieces may now be attached to the side cover. Ensure that the ball of the lever makes a good fit with its mating socket.
  3. Refit the cover, fitting a new gasket as required. Observe that the top right-hand setpin is longer than the other twelve.
  4. Refit the clutch housing with plain bearing plate against the bearing. Refit the speedometer drive, breather and dipstick.

Section F.7


(a) Jumping out of Gear

(b) Noisy Gearbox

(c) Difficulty in Engaging Gear

(d) Oil Leaks

Broken change speed fork sod spring Excessively worn fork rod groove Worn coupling dogs Fork rod securing screw loose Insufficient oil in gearbox Excessive end play in laygear Damaged or worn bearings Damaged or worn teeth

Incorrect clutch operation

Damaged joint washers Damaged or worn oil seals Front, rear or side covers loose or damaged

Section F.8


Commencing at engine number 11342, the gears were modified to increase their rigidity.
In earlier versions of this modification the laygear was fitted with plain bushes, but this was later replaced by a layshaft assembly with needle roller bearings.

The modified gears are only interchangeable with earlier types in complete sets.