How do you restore a Vincent damper.

A

aldeburgh

Well Known and Active Forum User
Non-VOC Member
I have one such damper on the operating table as I type, I thought I would just give them an oil change ready for the next rainy season , the front was straight forward enough just followed the instructions in the little orange bible and it works perfect. On applying the same procedure to the rear I could only get it to perform a half dozen strokes before developing free float, after draining and refilling a couple of times without any improvement I opened it up. It would appear that my rear damper has at some point been converted to use a lip type seal (good) but only one has been fitted ,so it keeps oil in under compression but lets wind in when under tension , probably been like it for years!.
Off to Ipswich now to give some money to somebody with two new seals.
 
Paul Ennis

Paul Ennis

Well Known and Active Forum User
VOC Member
aldeburgh,
IMHO, the only way to get rid of the free play (see my article MPH Oct 05) is to fit an air bag in the damper and fill it fully extended. Then as the damper rod enters the unit it's volume is taken up by compressing the air in the bag. As the air is 'contained' it can't get into the piston chamber and give the dreaded dead spot.

My air bag consists of a piece of bubble wrap wrapped around the outside of the piston chamber, ie in the oil reservoir.

Paul.
 
A

aldeburgh

Well Known and Active Forum User
Non-VOC Member
With regard to the learned gentleman above ,its all absolutely true and my damper is now good enough to grace any high perfomance machine (built in Stevenage) Thanks Paul!
 
b'knighted

b'knighted

Well Known and Active Forum User
VOC Member
When you press on bubble wrap the air moves away from your finger and overstretches the plastic alongside it until it pops. When the oil presses on the bubble it presses on its entire surface supporting it against bursting and making the air compress.
 
Paul Ennis

Paul Ennis

Well Known and Active Forum User
VOC Member
Thanks Ian,
Also, should the bubble-wrap deteriorate, the air will still remain at the top of the oil reservoir and can't get into the piston chamber........unless you turn your bike upside down.
Paul.
 
G

Grash

Forum User
Non-VOC Member
I've just tried the bubble wrap technique and it seems to work very well. The total bubble capacity must have been a little less than that of the shaft as a small amount of oil needed bleeding off when the piston was fully home. However no deadspots, very pleased,thanks for the idea.

For info, I'm using X section seals which give two lips per seal, no leaks on the bench, so far. (Supplied by Sealforce, www.sealforce.co.uk, 01382 489043, very helpful, no minimum order).

Graham
 
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