More about shocks (dampers, really)

[Recluse]

I have my shocks/dampers apart so I took some photos of the hex-style seal holder. It's a strange type of seal, kind of like a valve stem seal like SP3 thought. No internal metal reinforcing like a 'normal' oil seal would have, the only metal is the spring at the bottom. I guess the screw-on cap provides rigidity when it sandwiches the thick top rubber part into the holder? Hopefully my bearing supplier/seal house will have something similar or else the holders would need to be machined for standard oil seals as mentioned earlier in the thread. I might just clean and reuse the existing seals for now, they look pretty good actually.

oil_seal2.jpg

[SP3]

Thanks for posting that Recluse. Very interesting.

[DucRedux]

Thanks, Recluse, for posting the photo. (I’m not quite adept at that yet).
As you show, it is “button” type seal; that is, it has a wide flange which fits under the metal cap and then narrows into a dimension that fits into the holder socket. My measurements are different, however. The overall diameter is 22 mm, nominal, but the rod seal portion is 17 -17.4 mm OD with a depth of 5.5- 6.0 mm. If a seal of the latter, socket dimensions can be found, then a rubber washer, a “wiper ring” or seal backing ring with an ID of 10 mm can be placed under the cap to hold the now compound seal in place.

Manufacturers like SKF or Harwal in the US, http://www.harwal.com/, appear to make a dimensionally close hydraulic rod seal 10 (ID) X 18 x 0.57. This close match was found after exhausting my current eyeglass prescription scanning hundreds of diagrams, specs and sources. These manufacturers work through local distributors. I have located one in NJ. These seals are hydraulic rod seals, not oil seals and are “U”-shaped. The question is whether the snap fit tolerance of the design is large enough to accommodate placement into the 0.5 smaller diameter of the socket holder, or will the holder need boring to enlarge the socket?

[SP3]

All finished except for the pre-load decals. About ten times the effort any normal person would bother with. But, it's fun. New or really worked-over original parts. Ohlins fluid, new wear buttons for the shrouds, new seals, glass beaded springs (sprayed with WD-40 long-term corrosion inhibitor), polished the Al bits, powdercoated the steel shroud, polished shaft, valves completely apart/cleaned/assembled, 'honed' the piston tube with Scotchbrite, new preload collar balls, new chrome, and on and on.

[Dazoelry]

Thought I'd add my shock/damper rebuild.
The springs were already off.
I clamped the seal holder in a vice by its flats then unscrewed the body with a spanner on the mounting eye.

IMG_20210915_162954989rs2.jpg

The seal holder was the 3 crimp type.

IMG_4446rs2.JPG

I measured the level of the oil in the damper to the top of the body - this one hadn't been leaking and measured at 50mm.

IMG_20210915_163250028__2_exported_889_1631729161134rs.jpg

I mounted the seal holder in the lathe and carefully shaved off the crimps. Then knocked the old seal out with a slide hammer.

IMG_20210915_165142883_HDRrs.jpg

and then machined a groove (1mm wide 0.5mm deep) for an internal circlip.

IMG_20210915_165726961_HDRrs.jpg

[Dazoelry]

The original seal (GACO MIM1022, 22 x 10 x 7), internal circlip (22mm) and replacement seal - replacement seal is a 22 x 10 x 6 2RS, so has a scraper lip and seal lip.

IMG_20210915_171147953_HDRrs.jpg

Replacement seal and circlip fitted to seal holder. Pressed in using the vice and a suitable socket.

IMG_20210915_161957731_HDRrs.jpg

Completed shocks.

IMG_20210915_190130838rs.jpg

Filled with ATF to 50mm below top of lower body.
I did try 65ml, but once the damper rod was inserted some oil spilled out. On measuring the level after the spillage it was 50mm below the top of the outer body!
I hope this helps someone.

Does anyone know where I can get replacement plastic sleeves that sit between the shock body and the chrome spring?

Thanks to Eldert for pointing me in the right direction,covers can be found at -
https://www.ducativintagestore.com/1_pa ... esmo_mark3

[Eldert]

the plastic sleeves you can buy at the ducati vintage store in Italy

Eldert

[Jordan]

Dampers indeed!
The springs are the shock absorbers.

[Dazoelry]

Thanks Eldert, I'll check them out.