June 6 2024
Spent a bit of time checking the fork internals are right for the bike
Ages ago (1985?) replaced the Bitubo factory fitted dampers for FAC items which can apparently be serviced. At the same time I changed the single spring for the double spring dual rate option as fitted to the Spada.
These have the top fork bolt built in, unlike the originals which serve to locate the damper via an allen bolt through a separate large nut which screws into the chrome 35mm slider to create the top fixing for the fork internals.
Did some measurements and compared with Spada diagram (see picture) and apart from needing to preload the dual springs by about 10mm to locate the retaining circlip at the end of the fork, everything is as should be.
Over the years I've tried various methods of replacing the fork oil.
Draining is easy, just use a jack to raise the front wheel (wood boards under main stand), take out the wheel spindle, undo the bottom retaining bolts, and the old oil will ooze out.
Removing the whole wheel and mudguard and brake calipers is worth doing for ease of access. Adds about ten minutes to the job but might save fifteen. If you've done this tapping the fork leg (sleeve - #34 in exploded diagram below) down will make it run out real quick.
Refilling.
Undo the top fork bolt until it is possible to free the damper upwards (it may be necessary to tap the fork leg down as it tends to stick in place, so having the wheel calipers and mudguard off helps if this happens).
Put the bottom bolt back in and push it home. Find a way of holding it up there (a friend? a rubber wedge?). Pour in 60-80mm ATF into the gap between the top of the slider and the damper body as quickly as you can but giving it time to flow in).
Then immediately screw the top nut back into the slider and then, keeping a hand on the allen key at the bottom, push the fork leg up and tighten the bottom bolt. Tight. You may get a bit of leakage but not much can get out if you do all this quickly.
If you take the whole fork leg out all of this can be accomplished more easily, providing you find away of really getting the bottom bolt tight once the new oil is in.. With the fork out it is quite easy to clamp it upside down and find a suitable funnel and tube to do the refill from the bottom. (be sure to lift the leg a bit to create a space for the oil to flow in otherwise it will fill the screw hole and just come straight back out).
Note that the current set up has very tight rubber bushes at the top and bottom of the headlamp mounting bracket, which make pulling out the fork assembly very awkward. It helps a lot to undo the headlamp mounting bolts which allow these to be twisted a bit and frees the stiction so the forks can be pulled out with a strong downward pull and twisting action.
EXPLODED DIAGRAM
| 1 | 17 49 02 01 | 1 | Front fork |
| 2 | 14 50 45 02 | 2 | Upper cap |
| 3 | 90 70 62 38 | 2 | Gasket |
| 4 | 17 51 66 00 | 1 | Bush |
| 5 | 17 51 77 00 | 1 | Mark |
| 6 | 98 62 04 35 | 4 | Screw |
| 7 | 95 00 42 08 | 4 | Washer |
| 8 | 17 50 37 50 | 1 | Plate |
| 9 | 17 50 02 00 | 2 | Cap |
| 10 | 17 49 31 00 | 1 | Fork head |
| 11 | 98 62 25 35 | 5 | Screw |
| 12 | 95 10 08 37 | 1 | Washer |
| 13 | 10 51 34.01 | 1 | Nut |
| 14 | 14 49 46 00 | 1 | Cup |
| 15 | 92 24 92 25 | 2 | Taper roller bearing |
| 16 | 14 51 67 00 | 1 | Shim |
| 17 | 14 51 70 00 | 1 | Bearing ring |
| 18 | 17 49 40 00 | 1 | Fork yoke comp. |
| 19 | 17 49 27 00 | 4 | Rubber ring |
| 20 | 17 49 61 00 | 1 | R.H. stay tube |
| 21 | 17 49 62 00 | 1 | L.H. stay tube |
| 22 | 14 52 64 07 | 2 | Shock absorbeer |
| 23 | 92 63 01 06 | 2 | Self locking nut |
| 24 | 14 52 65 05 | 2 | Rubber ring |
| 25 | 90 27 10 14 | 2 | Snap ring |
| 26 | 14 52 76 00 | 2 | Cap |
| 27 | 14 52 78 00 | 2 | Tube |
| 28 | 14 52 79 00 | 2 | Tube end |
| 29 | 14 52 66 00 | 2 | Spring |
| 30 | 14 52 54 01 | 2 | Arm |
| 31 | 98 62 25 35 | 2 | Screw |
| 32 | 10 52 89 00 | 2 | Gasket |
| 33 | 98 62 24 22 | 2 | Screw |
| 34 | 17 52 25 20 | 1 | R.H. sleeve |
| 35 | 17 52 26 20 | 1 | L.H. sleeve |
| 36 | 98 62 05 40 | 2 | Screw |
| 37 | 92 60 22 10 | 2 | Nut |
| 38 | 98 62 03 12 | 2 | Oil drain screw |
| 39 | 95 10 01 16 | 2 | Washer |
| 40 | 90 40 35 47 | 4 | Seal ring |
| 41 | 14 52 45 00 | 2 | Dust guard |
| 42 | 17 55 02 00 | 2 | Rear suspension |
| 43 | 12 55 23 00 | 2 | Spring |
| 44 | 17 55 03 00 | 2 | Center head |
| 45 | 17 55 23 00 | 8 | Rubber bush |
| 46 | 95 00 42 15 | 4 | Inside washer |
| 47 | 95 10 03 37 | 2 | Outside washer |
| 48 | 92 60 22 10 | 2 | Nut |
| 49 | 95 10 02 55 | 2 | Outside washer |
| 50 | 98 05 44 16 | 2 | Screw |
