Roadholder forks

Internal if you want it to look standard.

Internal springs suffer from condensation, the rust gets into the oil to create grinding paste, hence if possible go external or change the fork oil frequently.

I'd say that the oil seal is meant to keep oil inside, not so good at keeping water out. Could be reason for fitting rubber gaiters. Though back then people fitted them because they liked the look.

I would have thought a '56 bike would have external springs. If it does have external and you wanted to use internal you would also have to buy all the damper parts as they are different. There is nothing fundamentally wrong with either. If your internal springs are rusting there is a problem, they don't rust habitually. 

The forks are not sealed and air is continuously pumped in and out, unless you are in Arizona the air will carry water vapour.

See attachment for options.

How/why is it that the forks aren't sealed? My roadholders have a fibre washers on the drain plug, fibre washers slider to damper, oil seals slider to stanchion and an alloy washers stanchion to top nuts. I stripped and rebuilt my forks just 3 weeks ago, for the first time in 10 years as 1 seal was 'weepy'. My (internal) springs were not rusty, they were remarkably oily in fact.

OK, maybe your forks aren't sealed?  - but if they all weren't that would be yet another oil leak path that would drive fastidious owners nuts.Mine certainly were and are, and the same goes for all the bikes I have. How else does the 'air spring' effect work with different levels of damper oil, and why is it important ( if you like to ride fast anyway) to have the same amount of oil in each leg if they aren't?

Just wondering?

Regards,

George

They were not designed to be air tight, as an example the stanchion does not finish at the top of the taper in the top yoke, this is to ensure a properly torqued top nut applies all of the force to the taper but it leaves a gap. That leaves two routes for air, down through the taper and up past the top fork nut. Ask Velocette how well their dowty air forks went in service, they lasted 6 years in production before they gave up and reverted to normal sprung forks. As for my forks I have the added issue of the clock holders being held onto the bike using the fork top nuts, adding another joint for leaks. I am sure you can get them air tight with additional O rings and as you have done with an alloy instead of steel top nut washer and careful assembly, but they are still forks not designed to be air tight, unlike modern forks with no taper and an integrated O ring in the top nut which when fully seated leaves no gap, double lipped fork seals, fork seal protectors and bottom bolts with copper washers that do retain air (but I replace this with a dowty washer).