leaking fork seals

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Oct 19, 2005
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I have just finished a complete restoration on my 1970 750 roadster and have been having a whale of a time running it in. The front forks started leaking almost immediately from the top seals in spite of the fact that I had replaced all of the bushes, gaskets, seals, dust covers and fork tubes. I have dismantled the forks to refit a new set of seals and to make sure I hadn't done something foolish like put the seals in upside down, but all seems to be in order. One thing I did notice is that the tubes have rather a matte finish in comparison to most other forks and I wonder whether this lack of a high polish might have something to do with it. These were genuine Norton items purchased from Norvil rather than the slightly cheaper replica tubes available from the same source. I am thinking of polishing the tubes on a buffing wheel, does anyone have any similar experience or observations?
Do the top fork bushes slide easily with no rocking on the fork tube? There have been instances of tubes made slightly smaller, although I would hope that Andover Norton would make sure that they are correct before putting the "Genuine Norton" tag on them. The matte finish probably indicates they are hard chromed rather than the "show" chrome of the old originals. This is a good thing if done properly as they should wear better. Stock tubes would wear through the chrome in the top bush area.

Could the seals have been nicked on installation? I usually use an aluminum tube as a drift to carefully seat the seals. And don't forget the paper washer under the seal.
Thanks for your reply Ron, I bought a bush and seal kit at the same time and from the same source and everything slides nicely with no rocking, neither is there any appreciable deflection under braking or clunking over bumps (yes I did remember the paper gasket). I understand that these are hard chromed but so are every other set of forks that one sees today and these others all have a polished finish, but without that bright sheen that you have with show chrome. The Norton ones have a slightly discernible grainy texture if you run your fingernail down them.
Hey Dave, I just don't like stock seals and use the( Leak Proof) brand in place of them. These seals float, That means that they are thinner than stock ones and when in use are free to stay in place on the fork tube on small chatter bumps. This saves a ton of wear and stiction. There is a set of these in a friends bike here in Michigan that have been in continuous use for 15 years. We pulled them out to do one of my kits and just put them right back in.
The only people who have problems with them don't know the top bush trick. You leave out the paper seal and file some chris cross grooves across the top of the bush to let a little oil underneth the the seal improving its prefomance of the seal.
My bikes have been apart many times because of trying out different set ups for front end kits. Many years no problems. norbsa
Norbsa, Thanks for the advice, unfortunately I cannot get leak proof seals readily in Hong Kong and I want to put the bike back together this weekend. I am fitting a Covenant damping kit while I have them apart and I will try the modified bush trick that you mention but with a new pair of standard seals since this is what I have available. I notice on this fork damping kit they supply 2 alloy dowels to block the original holes in the damper rod and 2 collars to go over the tubes but it seems to me that on extreme compression the damper rod shaft could actually hit these dowels which pass through the damper rod. I think I will braze the holes up rather than use these dowels. I might make some collars up myself for this modification for use on my other 3 commandos currently in the pending tray, it's not much of a chore and at around US $15 a pop I should save myself a bundle. I have this kit fitted in my cafe racer and I have to say the modification is a big improvement.
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