English French German Italian Spanish

Fitting damper tubes to long roadholders

Submitted by dan_field on Thu, 13/01/2022
Forums
Nortons - General

I know the principle of this has been discussed before - my pre featherbed ES2 has commando damper tubes and stanchions fitted but this is coming at it from a different angle - I have a friend who races a Mabsa in the genuine pre 60 scrambles class, it currently has BSA forks which are almost useless! So he’s thinking of fitting long roadholders, my question is whether there are any ways of fitting the later damper tubes and rods to long roadholders and keeping them genuinely pre 60 - or only using parts available before then - I know that rules out commando stanchions. 
cheers

Dan

Submitted by john_holmes on Fri, 14/01/2022

Permalink

In the SCRMC pre 65 trials only the externals need to be period correct and the internals can and are be exotic so review the rule book. You can add B44/A65 damper tubes and rods to BSA heavyweight forks, done this many times by machining the bottom of the fork lowers for the retaining allen bolt or just buy 65 onwards fork lowers.

Submitted by dan_field on Fri, 14/01/2022

Permalink

Thanks John but to my mind that’s the trouble with pre 65 trials, roadholder forks with cartridge internals etc etc.  Most of the bikes in the pre 65 scene would never have been seen in 1965! 

Some of the Scramble clubs have a Pre 60  class and a Modified Pre 60 class (which includes replica frames etc). The beauty of the genuine Pre 60 class is that they are genuinely Pre 60.

i suppose one question I would ask is can you make the short roadholder dampers work inside long roadholder stanchions? 

Dan

Submitted by john_holmes on Fri, 14/01/2022

Permalink

i suppose one question I would ask is can you make the short roadholder dampers work inside long roadholder stanchions? 

Yes you can, as long as you do not follow the error made by Norton when they drew up the Commando forks, who made the damper tubes too short making the damper valve hitting the damper tube top the full extension stop. Resulting in the sharp noise when you put the bike onto the center stand or when the forks extend fully. Fix is to lengthen the top bush or the damper rod or combination of the 2. Also check this does not send the damper valve into the bottom of the damper rod when the suspension is fully compressed before cutting metal. Or just ignore the noise.

Submitted by dan_field on Sun, 16/01/2022

Permalink

Thanks John,

good to know. I think the long/short roadholder hybrid forks were used in the Nomad so are pre 60 eligible

dan 

Submitted by dan_field on Tue, 18/01/2022

Permalink

Hi Michael, I’ve done that on an ES2 as well and it works well, but it was using the long roadholder stanchions that I was interested in as Commandos aren’t really pre 60! not that you can tell the difference from outside but this guy can win races and wants to do it right (unlike me!) - not winning races that is! 

Dan 

Submitted by paul_standeven on Fri, 04/03/2022

Permalink

Eddie Dow damper kit, it may make the bike handle acceptably. Try a Gold Star arts supplier. There may be a way to make a post '65 BSA / Triumph damper fit the earlier fork - I hear they work very well.

Submitted by john_holmes on Fri, 04/03/2022

Permalink

If you do add damper rods etc double rate damping to previously single rate damping forks then you have to first defeat the single rate damping. This single rate will normally be holes near the bottom of the fork tubes to limit the flow of oil into and out of the chamber between the top and bottom bushes. You need to either open out the current holes or add extra holes. The Commando tubes have 200 mm2 of holes in the bottom of their fork tubes.

 



© 2024 Norton Owners Club Website by 2Toucans