DS 19 OPERATION No. DS 334-3 Work on the gear control. Op. DS 334-3 239
TOOLS
D - Make sure that the distribution of pressure is correct for each gear.
Raise the front of the car with the engine running at accelerated idling speed. Engage 1st gear and observe the
clutch fork; it should move slowly towards the rear (engaged position).
Carry out the same procedure for the four other gears.
If the fork remains in the declutched position, it is necessary to repair the hydraulic gear selector.
NOTE - One can also carry out this operation by means of the test bench 2290-T (see Op. DS 334-0, paragraphs 6
to 12) or better still, check the leakage as indicated in the operation DS 391-0).
E - It is possible to check the operation of a removed hydraulic gear selector by means of the test bench 2298-T. . . . Test bench 2298-T
Dismantling (see Pl. 70).
28 Fix the hydraulic gear selector in a vice by the rear cover end (stand MR-3053-200, see Pl. 71, fig. 4) . . . . . . . . Stand MR-3053-200
29 Remove the nuts fixing the union plates of the pipe assembly connecting the hydraulic gear selector to the gear
change speed control.
Remove the gear change speed control and bracket. Remove the pipe assembly and seal plates. Replace the nut
fixing the bracket and the front cover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 mm spanner
8 mm box spanner
12 mm box spanner
30 To remove the front cover (5) :
Unscrew the screws and nuts progressively in order to avoid jamming the cover. Remove the cover, the springs
(4) and (7), the spring cups (8) and (9), the vellumoid joint, the ring seal (1) of the automatic gear control piston
(3) (on the first models only).
Remove the automatic clutch control piston (2).
NOTE - On the second assembly model, the synchronising pistons (11) are positioned by the spring cups (28) and
(29) and the pistons are slightly different (see fig. 6), the spring (30) is also different.
Remove the gear control valve (10).
Remove the 3rd speed synchronising piston (11) and its joint. Raise the 2nd speed piston (31) by pushing with
the clutch control valve (12). Immediately after their dismantling, put the pistons (3), (11) and (31) in a
wooden rack (rack MR-3053-210, see Pl. 71, fig. 3).
Clean the bores of the hydraulic gear selector with alcohol, blow out with compressed air.
Check the diameter of the bore at “d’ (see fig. 2), between the end of the selector and the first groove. Use the
plug gauge 2277-T (see Pl. 71, fig. 1), and check the diameter in several positions.
If the “not go” end can be inserted or if deep scratches exist in the bore, the selector is unusable . . . . . . . . . . Plug gauge 2277-T
31 To remove the synchronising pistons :
Rack MR-3053-210
Press on the valve (12) using a brass drift in order to remove the pistons. Place them in the rack in the order of Rack MR-3053-210
disassembly Brass drift = 5 mm dia.
Remove the auxiliary clutch control valve (12)
Length = 60 mm.
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