FF: Forks Damper Piston Rod

[powella]

Came across these the other day while rebuilding.
Top Piston rod is used while the lower has not been used and can be seen to have a " O " ring in the Piston part.
The questions are , should there be a ring in the gap , and was this a factory or private modification ?
All other dimensions are exactly the same.

 

[Bill Thomas]

Not sure if this helps, The mods have been done to mine , But I can't remember much about it,

https://www.vincentownersclub.co.uk/resources/updating-vincent-dampers.1399/

Works well. Cheers Bill.

 

[LoneStar]

I don't think it's factory, based on ones I've seen. But I haven't seen that particular mod documented anywhere, either. Not sure what benefit it provides. There might be some minor leakage past the bare piston as it strokes, but all that would do is reduce damping a very small amount.

 

[Bill Thomas]

Paul Ennis is a well known Rallyist and ex Club Racer, And all round Clever Bloke. In UK,
The standard Damper was known for leaking and Pauls MOD' has been used a lot for a long time.
Cheers Bill.

 

[LoneStar]

Is this mod explained in any online document? I don't understand how an O-ring on the piston can prevent fluid from escaping the damper unit.

 

[Bill Thomas]

Just took an old one apart, Looks like the standard one has NO O ring, Just a plain piston.
Cheers Bill.

 

[BigEd]

Is this mod explained in any online document? I don't understand how an O-ring on the piston can prevent fluid from escaping the damper unit.

An "O" ring on the piston will have no effect on leakage from the damper. The end that screws into the body is where a good seal is best fitted to stop leaks. I think Paul uses an "X" ring seal in that position.
I did this mod years ago with maybe some improvement but have now used an AVO unit for several years on the Girdraulics and that gives consistent, good, adjustable, damping and has no leaks.

 

[Bill Thomas]

I still use a Spax Damper on one of mine, I have used it on a few Bikes and while Racing,
Just because one bloke in AUS got hurt, They took it off the market !.
In the past I have Snapped Standard Dampers !,
But the Standard and modified one Don Alexander did for me is on the Comet now.

 

[BigEd]

I still use a Spax Damper on one of mine, I have used it on a few Bikes and while Racing,
Just because one bloke in AUS got hurt, They took it off the market !.
In the past I have Snapped Standard Dampers !,
But the Standard and modified one Don Alexander did for me is on the Comet now.

Don was such a great guy and knew almost everything there was to know about a Vincent. A dedicated Club and Section man he is sadly missed. We lost another three section members recently, Stuart Howe, George Spence and Martin Fox. We are going to be a bit thin on the ground when we can restart our weekly Friday night meetings.

 

[vibrac]

As Big Ed says making the piston more efficent is not improvement Paul Ennis has the solution mods that work. back in the day I used to fit a oil seal in the damper top from a long gone car speedo drive and also a recirculating ball valve that went in the bottom of the damper and exited on the side above the pistion so it was closed on bump and open on recovery so like the original it relied on the piston not sealing completely
anyway I raced with dampers like that for years till Koni came along