Dear fellow Ducati enthusiasts, Currently I’m overhauling the Showa front fork of my 1992 750 Supersport. It’s the non-adjustable one, model GD 031 if I’m not wrong. So far, the inner tubes have been chromeplated and I have found all necessary replacement parts and seals except for the seal mounted in the bottom slider (see images). This seal is not included on the Ducati parts list. (And no, it's not number 19 on the image below as that's the lock ring wrongly referred to as 'gasket'). Is there a Ducati part number for the seal which sits in the bottom slider? Or has anybody got the exact measurements (besides the inner diameter of 41 mm) and especially an advice what rubber specification to look for? After having removed the bottom sliders by heating them up and burning the threadlocker I'd like to also remove the seals and not re-use them. Thanks!
Ronald, I have messed about with different set of forks in the past, I presume the inner stanchion screws into the bottom bit. Is the seal you are referring to not just an o-ring? Cheers Gaz
Hi Gaz, it's indeed about the o-ring in the bottom bit into which the stanchion is mounted. I'm always a bit careful with rubber parts if I don't have a replacement yet. So I have not taken out the seal yet, but it looks like a plain o-ring to me.
It should be pretty easy to get out. You may be OK with finding your own replacement if not I work with o-rings quite a lot, if you measure the o-ring section and the stanchion o.d. we should be able to find something off a well known web site. Nitrile or Viton will be ok. If you have a little pick you could look at hooking it out. Or a paper clip bend 5mm at the end, just file the paperclip end so it is rounded and smooth and there are no burrs on it. But it may look OK and you choose to leave, no problem. Sometime I press a bit of blue tack into groove and measure that to get the groove width. That should correspond to the o-ring size and depth. Cheers Gaz
Hi Gaz, Got it: inner O-ring diameter 39,0 mm and o-ring section 2,0 mm. Further, I was advised by a suspension specialist to order either NBR70 or NRB90 o-rings (nitrile indeed). Thanks for your support! Kind regards, Ronald
Ronald, That's good. 90 is quite hard and probably will have difficulty finding them. 70 is standard and you will get them most places. I will have a look at size and see what standard it is, but looks like your sort. Cheers Gaz
