Thwaites SPRITE NIMBUS, Manual

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SERVICING 40M-3 GEARBOX - SPRITE/NIMBUS MODELS
RE-ASSEMBLY OF MAIN GEARBOX: CONTD.
5. Before pressing the ballrace into place, the layshaft must be supported by placing a
steel packing about 3/8" thick between the gear (item 78) and the casing, otherwise
the bush (item 76) will be driven out, and it will not be possible to press the ballrace
(item 70) into place. With the ballrace pressed fully home, and the circlip (item 68)
fitted, remove the packing and fit the snap ring (item 69). This positions the layshaft
correctly.
6. Now fit the mainshaft ballrace (item 57) and its circlip (item 58). Pass the mainshaft
through the front of the gearbox, and feed on, in this order, the sliding gear (item
44), the second speed gear (item 56), the spacer (item 40), and the output gear (item
39), (with the narrow boss outwards). They must all be located on their correct shaft
diameters as the shaft is entered into the ballrace. Press the shaft home.
7. Fit the primary shaft (item 26) and front extension housing (item 8).Important:
Note: the oil feed hole in the gasket (item 21) and the extension housing. These must
be properly aligned with the oil feed hole in the case. Fit the lower selector fork
(item 79) and shaft (item 55). It is an advantage when fitting the selector forks, to use
a short piece of ½" diameter rod, fitted through the fork to retain the ball and spring
in position. The fork, with the rod in place, is passed into the box, and the selector
shaft is then pushed through from the rear of the case, and the fork, pushing out the
piece of ½" rod in the process. Secure the shaft by means of the retaining plate (item
75) and position the fork in the neutral position. Fit the interlock plate (item 50) and
pick up one of the interlock studs (item 51) with a clevis pin. If the slot in the fork is
not in line with the plate adjust the position of the plate by screwing up or
unscrewing the interlock stud to correct the error. Adjust the opposite interlock stud
to suit, fit the remaining clevis pin and split pin up. The upper fork and shaft are then
fitted in a similar manner to the lower one. The retaining plate (item 75) being
removed and refitted so that it secures both shafts.
8. When this is correct the Welch plugs (item 77) should be smeared with suitable
sealing compound and driven home. NB. item 77 - sealing discs.
9. Move both selector forks, so that two speeds are engaged, and the gear train locked.
Fit spacer (item 30), refit the end cover (item 29) in its correct position, fit coup-ling
(item 33) and washers, and tighten and tab the coupling bolt. Put the forks back in
neutral and fit the top cover and gear lever assembly. If the flats on the sides of the
pivot ball are worn, or if the spring retaining plate (item 47) is worn on the
under-side, they should be replaced.
10. Check that each speed is easily obtained, and that the gearbox rotates freely in all
speeds.
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