35mm Marzocchi lower fork seal-what type of O ring

[Ducati350ontario]

Hi. I'm having problems finding anything in the 35mm Marzocchi parts listing for what type of O ring or quad type seal belongs in the lower part of my 69 350 Scrambler front forks.

lower fork leg seal.jpg

When i got the project both forks had old rubber O rings in them, but they looked terrible, and Im not sure they were correct to being with. There is a square groove cut into this part,... which makes me think it should be quad style seal vs an O ring.



Anyone know what belongs in this grove and if anyone selling Ducati stuff online has something just for this?

Thanks
Jeff

[Jordan]

I've never seen this part - a special repair piece?

The square profile groove is normal for a round section O-ring, gives space for it to bulge into.
A starting point for the needed ring is:
thickness = width of the groove
inside diameter = diameter at bottom of groove
outside diameter = diameter at bottom of groove PLUS width of groove.

[Ducati350ontario]

I've never seen this part - a special repair piece?

The square profile groove is normal for a round section O-ring, gives space for it to bulge into.
A starting point for the needed ring is:
thickness = width of the groove
inside diameter = diameter at bottom of groove
outside diameter = diameter at bottom of groove PLUS width of groove.

Hi Jordan.
The right side fork has the same piece except its got two slots in it (like the lower slider) so when you tighten up the pinch bolt it clamps onto the axle.

I've never been able to find these pieces shown on any of the parts diagrams or random photos on the internet. All the other fork internals match the 35mm Marzocchi parts views perfectly so I'm fairly confident that's what these forks are.

[amartina75]

I don’t think that part is meant to be removed or serviced. It’s not even shown in the parts diagram. I’ve noticed what looked like a pressed in part from the bottom of the fork legs before and wondered about it but never tried to remove it.
I have a junk set somewhere but don’t feel like searching though boxes and making a mess of things.

You should be good with doing as Jordan suggested, just measure your cross section, which is 4.5mm and the diameter at the bottom of the groove will be your ID, find an o’ring with that CSxID

Also that is two parts you’re holding, not one. The smaller piece with the taper on top should have stayed attached to the dampener tube when you removed the tubes from the fork legs. The bigger piece should have stayed in the fork legs.
(Edit: there are different versions of those forks, that might be one piece. I haven’t had a set apart in several years)

I attached a pic from the bottom of my forks you can see the different looking cast vs machined aluminum look so it’s supposed to be there but I didn’t know it could be removed. I assumed it was pressed in, I guess that was easier to produce.

41579A1E-7E79-4C0A-8B14-4C5EF73E3C1F.jpeg

[Ducati350ontario]

Also that is two parts you’re holding, not one. The smaller piece with the taper on top should have stayed attached to the dampener tube when you removed the tubes from the fork legs. The bigger piece should have stayed in the fork legs.
(Edit: there are different versions of those forks, that might be one piece. I haven’t had a set apart in several years)

I attached a pic from the bottom of my forks you can see the different looking cast vs machined aluminum look so it’s supposed to be there but I didn’t know it could be removed. I assumed it was pressed in, I guess that was easier to produce.
41579A1E-7E79-4C0A-8B14-4C5EF73E3C1F.jpeg[/quote]

Hi, thanks for the response.
I'm positive both these things are one piece and they are supposed to have a seal (an O ring) in them. They both had O rings so I put them back together with O rings and the other fork is just fine. I think my problem is that this lower stantion is likely not round anymore and there is a small amount of scoring where the seal goes.

The dampening rod sits down inside the narrow piece and then the Allen bolt comes up from the bottom to hold the dampening rod in place.

2thumbnail_Inked35mm Marzocchi fork-350 SCR_LI (1).jpg

-jeff