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Length of Roadholder Fork Components #470608
01/04/13 4:41 am
01/04/13 4:41 am
Joined: May 2005
Posts: 114
Gippsland Australia
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ogrilp400 Offline OP
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ogrilp400  Offline OP
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Posts: 114
Gippsland Australia
Dear All,
Can some tell me or point to where I might find the length of the stanchion, damper rod, damper tube and slider of the various Roadholder forks? The roadholders on my Norvin seem to have very little stroke and it may be that I have mixed components.
Thanks.

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Re: Length of Roadholder Fork Components [Re: ogrilp400] #470666
01/04/13 5:29 pm
01/04/13 5:29 pm
Joined: Aug 2001
Posts: 1,264
Hamilton, Mass. USA
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Dave Comeau Offline

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Dave Comeau  Offline

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Joined: Aug 2001
Posts: 1,264
Hamilton, Mass. USA
Some of what you want is here on my web site.

http://atlanticgreen.com/forks.htm


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: Length of Roadholder Fork Components [Re: ogrilp400] #470717
01/04/13 11:06 pm
01/04/13 11:06 pm
Joined: Aug 2001
Posts: 2,116
Oztralia
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Rohan Offline
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Rohan  Offline
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Oztralia
Lot of detail still required there to be complete.

Didn't we see that Commando's realistically only get 4" of travel, if that.

A short roadholder with 6 inches of travel would have most featherbeds scraping their frame down the road ?!

Manx forks (short short roadholders) only get 1 & 1/2" of travel ??

Re: Length of Roadholder Fork Components [Re: ogrilp400] #471010
01/06/13 6:20 pm
01/06/13 6:20 pm
Joined: Sep 2002
Posts: 537
belgium
ludwig Offline
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ludwig  Offline
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belgium
lots of info here :
http://www.members.shaw.ca/randell/roadholders.html
( but discard the part about RT valves .. )

Last edited by ludwig; 01/06/13 6:22 pm.
Re: Length of Roadholder Fork Components [Re: ogrilp400] #471107
01/07/13 3:10 am
01/07/13 3:10 am
Joined: Aug 2012
Posts: 612
Oregon
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Dana_twin Offline
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Posts: 612
Oregon
You can read tons of articles and they all say different things about Norton/AMC forks in general. Some articles talk about the length of the damper tubes and others about length of the damper rods, or 2" extensions to the damper rods. For example I have two sets of damper tubes here (definitely 1960's AMC) and neither damper tube set matches any of the spec lengths in any articles I have seen on the web, and I have looked at plenty. My hunch is that with so many variants like the Manx, P11, ES2, G15 Matchless, AJS, Norton Atlas and Commando, N15 etc etc etc it's kind of a grab bag as to what has been fitted over the years. So it would be nice but perhaps a Herculean task for someone who really knows these front ends to come up with a correct matrix to show stanchion length, damper rod length, and damper tube length by model.

Re: Length of Roadholder Fork Components [Re: Dana_twin] #471161
01/07/13 11:40 am
01/07/13 11:40 am
Joined: Dec 2004
Posts: 9,332
Scotland
kommando Offline
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kommando  Offline
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Posts: 9,332
Scotland
Quote:
( but discard the part about RT valves .. )


The RT valves are a valid mod, they do work as designed as long as you can seal the outside against the stanchion.

Re: Length of Roadholder Fork Components [Re: kommando] #471253
01/07/13 9:24 pm
01/07/13 9:24 pm
Joined: Sep 2002
Posts: 537
belgium
ludwig Offline
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ludwig  Offline
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belgium
Originally Posted By: kommando


The RT valves are a valid mod, they do work as designed as long as you can seal the outside against the stanchion.


For compression damping : yes .
For rebound damping : never .
I tried to make them work , till I found out they where never intended to control rebound .



Re: Length of Roadholder Fork Components [Re: ogrilp400] #471322
01/08/13 8:48 am
01/08/13 8:48 am
Joined: Dec 2004
Posts: 9,332
Scotland
kommando Offline
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kommando  Offline
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Posts: 9,332
Scotland
The problem with the RT valves being used as rebound seems to be specific to the Norton application. I have them in Triumph forks as rebound dampers and the oil does aerate and I have been looking for the problem. There are differences in the design when applied to Triumph shuttle valve forks compared to Norton but which of them individually or collectively cure the aeration I cannot say.

1. Triumph forks seals are double lipped instead of Norton single lipped. On the bench you can feel the air compress inside the forks and the excess air slowly leaks from the threads of the fork top nut over a few minutes. On extension with no springs in play the forks try to pull back due to the reduced internal pressure until the air leaks back in through the top fork nut. Not tried this on the Norton forks but the single lipped seal maybe where the air is coming from.

2. The Triumph forks have external springs and no damper bodies so the valve is held fixed in the stanchion near the bottom and the external RT body seal is a static seal ie not sliding.

3. As the forks compress the RT valve moves downwards relative to the Fork bottom instead of being static on top of the damper body and using a sliding seal on the stanchion.

4. The RT body is custom made to provide a groove in the body for a X ring seal and the OD is a sliding fit inside the stanchion.

Re: Length of Roadholder Fork Components [Re: ogrilp400] #471402
01/08/13 6:52 pm
01/08/13 6:52 pm
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bon Offline
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What , would anyone happen to know is the distance from the centre of the front axle to the top of the top yolk on the short roadholders as fitted to the 60's nortons ?

Re: Length of Roadholder Fork Components [Re: ogrilp400] #471440
01/09/13 12:15 am
01/09/13 12:15 am
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Posts: 2,116
Oztralia
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Rohan Offline
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Rohan  Offline
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Oztralia
Stock, unladen generally will be around the 28 or 29 inch mark.
Thats if the 'tuners' haven't been at them.

Where are yours at ?

Re: Length of Roadholder Fork Components [Re: Rohan] #471506
01/09/13 4:13 pm
01/09/13 4:13 pm
Joined: Nov 2009
Posts: 623
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bon Offline
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Originally Posted By: Rohan
Stock, unladen generally will be around the 28 or 29 inch mark.
Thats if the 'tuners' haven't been at them.

Where are yours at ?


Haven't measured them, but as i was told they were off a commando i think they are going be too long.


Moderated by  Dave Comeau 


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