31.5 Narrow case forks

[Bevel bob]

I have never stripped these forks ,are there any pitfalls,and does anyone know where to get the odd section ring seals that fit on the top nuts?.

[DucRedux]

The 17.5 mm o-rings for the fork cap nuts are available on line. I've sourced them to use, but after one broke after a number or fittings while sorting threads, I found a usable replacement ring from a hardware and plumbing section. (Danco makes faucet o-rings available at home centers and are indexed by diagram and part number for comparison. Some Sears and Ace hardware stores carry a large selection of metric and standard o-ring sizes. In short, look and you will find them. Trials will sort out the ones that fit best.)

My experience is: a) The bottom damper stem securing screw has joint compound, the area may need to be warmed to remove it. b) If the screw turns but does not release, it is because the whole stem is turning inside the fork tube - insert a wooden dowel pressed against the stem piston to keep steady c) When the piston and damper stem are later removed, inspect the top of the piston which is slotted and then devise a rod type tool for reassembly. d) The C-clip which holds the fork valve in the tube may very difficult to remove from its groove. On one fork tube I resorted to angle drilling a precise, tiny hole in the groove from the inside out. The small hole allowed the C-clip to be rotated in the groove so that one end could be pushed up and out by a pin inserted from the outside of the tube through the drilled hole. e) The hydraulic valve in the damper contains tiny loose ball bearings. If the valve is stuck in the tube, tap it out while the end is contained in a plastic bag or or else you will be hunting for bearings on your hands and knees!

[JimF]

viewtopic.php?f=3&t=773&p=5354&hilit=fork+tool#p5354

I am hoping this old post of mine will help you. Let me know if you have any questions. It's been years since I took mine apart, but after fabricating this took for a couple of dollars the forks came apart and went back together with no other special tools.

The only thing I would warn you about are the fork legs themselves. I think out of six or eight fork legs I have that came off my two bikes with 31.5mm forks plus a couple of spares I bought at a swap meet I only ever found one leg to be perfectly straight. I've always been lucky enough to have access to a machinist's granite table and I just roll the fork tube on the table to look for a wobble. If it wobbles I have a fellow with a hydraulic press and some v-blocks straighten the fork tubes for me.

If you don't have access to a granite table you can use plate glass.

Jim

[amartina75]

Jim is so right about the fork tubes. I think the general rule is nicer the tube is as far as pitting and rust goes the more bent it will be. The more pitted and rusty they are the straighter they will be.

I straightened some as Jim described. It is not that difficult.

There are a few different designs of the damper valve that holds the ball bearings. The particular one that has some of them staked in is prone to failure. Leaving loose balls at the bottom of the legs. My forks from a 66 scrambler were like that.

Also check the parts for wear particularly the damper piston, if the tubes are bent the piston wears on one side from rubbing. Mine had to be machined down and sleeved.

Don't be afraid to get into it though, it's not that complicated.

Good luck
Aaron

[DucRedux]

Bevel Bob: Apologies for not first noting your address for my previous reply. Classic Ducati show that their store carries the o-ring seals for 31.5 mm forks: http://www.classicducati.com/index.php? ... at&catId=9

An internet search indicates that DIY stores like B&Q carry o-ring assortments in their plumbing sections. Good luck.