Front Fork Service

[Magman]

My front forks (1969 350 Mark 3 or Sebring) have very old oil stains caked below the fork seals. The bike sat for over 30 years and I'm guessing the fork oil seaped out over time. The front suspension is very week. If I hit the front brake moderately or go over a medium bump the forks can bottom out. I must attend to this right away so no damage occures. I have Tom Bailey's excellent workshop manual but there are special tools involved and considerable work to disassemble, clean and reassemble the front forks and triple tree. I would prefer to simply drain and refill the forks and see if I can get the seals to rehydrate and forks to function acceptable before buying special tools and attempting a complete teardown. I have a few questions hoping for some advise.

1) What size internal hex wrench do I need to remove the upper plugs?
2) Can the upper plug be removed and reinstalled with arm force if the forks are unloaded and fully extended?
3) Do I have to turn the forks upside down to drain the fork oil or is there a drain plug or other drain method?
4) Where do I purchase fork seals, gaskets, etc if I do need to replace them?

thanks
Steve

[double diamond]

Seems to me the fork cap sockets are 14mm, but measure across the flats to be sure, they might be 12 or 13mm. The springs on the fork are external (under the shrouds) so there is no spring under compression that the caps are preloading. There are drain screws on the slider to drain the fork oil, although you may be a bit optimistic thinking that what’s in there will drain out. Guzzino.com would be the first suggestion to find fork seals. Doubtful that your seals will hold oil. The shrouds on the fork tend to collect dirt, rust etc. and it accumulates right on top of the fork seal, which not only ruins the fork seal but also scores the fork tube. Also, the external springs rub on the fork tube and compromise the sealing surface and the springs and fork tube become rusty since neither have any surface treatment (i.e. plating) to inhibit rust. It’s a pretty poor design in this regard. Most forks I’ve disassembled need new tubes (or ground/hard chromed to restore the sealing surface) to really hold oil as they should. Matt

[Magman]

I dont know what front forks I have to buy seals. Guzzino.com has seals for 3 different types. There is a 30mm, 31.5mm and 35mm.
What forks do I have?

[double diamond]

You have the 31.5mm fork.

[Nick]

To re-hydrate the seals you can try adding some automatic transmission 'stop leak' fluid to the fork oil. This stuff softens old seals. If you find the fork bottoming, you can try some thicker fork oil. Still, it shouldn't be hard to find seals that fit. Lacquer thinner should remove any stains on the fork tubes.

If the tubes are pitted, you can fill the pits with Epoxy or liquid steel, then carefully sand smooth with fine paper.

Re. the top wrench, you don't need one. Just get a 14mm bolt (or whatever size it is, put two lock nuts on the threaded end, and there's your wrench! You can use this for the big allen bolt on the left side case as well. Instead of double-nutting the bolts threaded end, you can also bend it 90° and use it as wrench.

If the fork still bottoms, you can make some plastic/metal spacers to give the springs more pre-load.