Tech Library - Showa Fork Oil Change

A useful technical article from Derek

Changing the Oil on Showa forks

You will need the big washer with a slot cut in it, a length of wire (I used electrical cable) and a something to pull the spring down with (a couple of screwdrivers in my case but I have now made a special tool to make this part easier). Most importantly you will either need to grow a third arm or enlist a helper.

Here are my home made special tools


Loosen the fork top nuts first while the legs are still clamped in the yokes.

Deal with one leg at a time. Clamp the bottom of the leg in with soft jaws and undo the top nut. The upper part of the fork will slide down leaving the damper rod and spring attached to the nut. There is a tubular spacer between the spring and top nut, also a plastic piece. Insert a screwdriver into each hole in the spacer (or use the special tool) and push down to compress the spring. This will allow your third hand to insert the slotted washer to under the locknut so that the spring remains compressed enough to undo the top nut from the damper rod.

Having removed the top nut, get your third hand to remove the slotted washer while you once again compress the spring. You can now release the spring and remove it and the spacers - note their positions and that the spring has the closed coils at the top. Empty all the old oil out and pump the damper a few times until it is all out.

Now the fun begins. With the spring out fill the tubes to recommended level (492cc ± 2.5cc OR 94mm from the top of the fork tube with the tube fully down) I used 5 weight fork oil. Pump the damper rod about 9 or ten times. Do this very slowly because oil will spout out the orifice in the top of the rod once the damper is full as you pull the rod up. Re-check the level and adjust as necessary. Then, after replacing the spring the right way round, tie a length of wire to the top of the damper rod and thread it through the spacer and plastic bit and use it pull the damper up through them. Tighten the compression damper adjustment all the way in , this will help keep the damper rod extended while you do the next bit. Now get your third hand to hold up the damper rod and slip the slotted washer in place while you compress the spring as before. I found the easiest way was to tie the wire to the garage roof leaving my assistant to simply insert/remove the washer as required.
Before refitting the top nut, screw the rebound damper screw all the way out and then back in again by 14 clicks. Screw the top nut all the way down on damper rod and then tighten the locknut. Remove the wire and slotted washer, lift up the fork upper tube and screw the top nut back in (Ideally it should have a new o-ring).
Refit the stanchion to the bike at the same level as before, tighten the yoke clamps and then the top nut.
Repeat for the other leg. When the forks are back on the bike remember to reset the rebound, compression and preload settings.
Hope this is of help. Have fun and see if you can do it without drenching yourself and the workshop with fork oil :-)

'03 ST4s ABS

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