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Stanchion Length #359541
02/23/11 2:01 am
02/23/11 2:01 am
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Lynchburg, VA.
Peter B. Offline OP
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I stripped down the forks tonight as part of my 1960 99 restoration. Since the stanchions are somewhat rusty where they are covered by the shrouds(as usual), I was thinking of replacing them. Here's my quandary - when I look at the Norvil site, it lists the length as 21 7/8" for the short Roadholders - yet mine measure 19 7/8"! Was 1960 a special year, are the stanchions from a different model for some reason, or any ideas? What is the 'correct' length? The NOC sells them too, but doesn't list the length.


Peter B.
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Re: Stanchion Length [Re: Peter B.] #359603
02/23/11 2:26 pm
02/23/11 2:26 pm
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Russ Hunt Offline
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Once you find the correct length you might try Forking By Frank for the new tubes. In the past I've gotten them for my Commando and also a Matchless scrambler and they were fine.

Re: Stanchion Length [Re: Russ Hunt] #359614
02/23/11 5:02 pm
02/23/11 5:02 pm
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norton bob Offline
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the correct length is 21.7/8" same for all road featherbeds with short roadholders, normally unplated where covers used.Cheap plating is not an improvement.

Last edited by norton bob; 02/23/11 4:59 pm.
Re: Stanchion Length [Re: norton bob] #359678
02/23/11 9:14 pm
02/23/11 9:14 pm
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Lynchburg, VA.
Peter B. Offline OP
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Originally Posted By: norton bob
the correct length is 21.7/8" same for all road featherbeds with short roadholders, normally unplated where covers used.Cheap plating is not an improvement.


Any idea how mine could be 2" shorter, and why? The bike sat normally, what happens if I put in new ones taht are 2" longer????


Peter B.
Re: Stanchion Length [Re: Peter B.] #359684
02/23/11 9:48 pm
02/23/11 9:48 pm
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Rohan Offline
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If someone has chopped your stanchions down to 19", your bike must sit very low to the road ? And not have much fork travel ?

If this doesn't look the case, you need to investigate what else has been done - shorter rear shocks ? - someone with short legs was lowering the whole bike ??

hth.

Re: Stanchion Length [Re: Rohan] #359709
02/23/11 11:25 pm
02/23/11 11:25 pm
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Lynchburg, VA.
Peter B. Offline OP
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Originally Posted By: Rohan
If someone has chopped your stanchions down to 19", your bike must sit very low to the road ? And not have much fork travel ?

If this doesn't look the case, you need to investigate what else has been done - shorter rear shocks ? - someone with short legs was lowering the whole bike ??

hth.


I'll post a picture of the stanchions, definitely not cut-down, rear shocks were/are standard length, so it's really puzzling. Bike never sat weird, I'll post a pic of it before I started the resto too. I didn't even think you could get stanchions this length, I've never seem them referenced anywhere.

Someone out there must have an idea!

Thanks all.


Peter B.
Re: Stanchion Length [Re: Peter B.] #359717
02/24/11 12:13 am
02/24/11 12:13 am
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Lynchburg, VA.
Peter B. Offline OP
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As promised, here's a few pictures:

Here's the bike before I started the tear-down. Doesn't seem to sit low in the front.


Picture of the forks removed from the bike before disassembly (I had loosened one of the fork seal holders):


And a picture of the 'short' short stanchions, 19 7/8". Obviously not cut or modified:



Any ideas?


Peter B.
Re: Stanchion Length [Re: Peter B.] #359736
02/24/11 1:08 am
02/24/11 1:08 am
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Lynchburg, VA.
Peter B. Offline OP
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Here's some additional info that may give someone an idea of what the deal is. The springs on my bike measure 17 3/4", new ones are listed as 18.687" long. So I have shorter springs.

The length of the damper/damper rod assembley fully extended is 27". Damper rod, when detached from the damper tube, is 19 7/8" long - same length as the stanchions. If anyone has a 'standard' Roadholder apart and can measure this same combo, I'm guessing it will be slightly longer than mine.

Has anyone ever heard of special order forks form the factory, maybe someone wanted a lower ride?

Last edited by Peter B.; 02/24/11 1:22 am.

Peter B.
Re: Stanchion Length [Re: Peter B.] #359749
02/24/11 1:45 am
02/24/11 1:45 am
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Rohan Offline
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Why would it be factory ?
I've seen Commando stanchions cut down to fit short roadholders, anyone with a lathe can do this. (don't know what else was done, before anyone else asks...)

Your front forks do look shortish. I'm thinking off the centrestand, you are not going to have a lot of suspension travel there.

Rear shocks don't exactly look factory original either, so someone has been at the suspension...

P.S. Nice bike, good to see some colour.
Any pics anywhere of your siamesed exhaust ?
Good to see at least one example has survived, must be quite rare ?

Cheers.

Last edited by Rohan; 02/24/11 1:55 am.
Re: Stanchion Length [Re: Rohan] #359751
02/24/11 2:04 am
02/24/11 2:04 am
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P.S. What length are your rear shocks ?

PPS. There are sidecar versions of these forks - I have a top yoke, not sure of year, that is stamped S/CAR.

I believe they also had heavier sprngs to suit.
Never met anyone who knows anything about them.

Re: Stanchion Length [Re: Rohan] #359765
02/24/11 3:01 am
02/24/11 3:01 am
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Lynchburg, VA.
Peter B. Offline OP
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Originally Posted By: Rohan
Why would it be factory ?
I've seen Commando stanchions cut down to fit short roadholders, anyone with a lathe can do this. (don't know what else was done, before anyone else asks...)

Your front forks do look shortish. I'm thinking off the centrestand, you are not going to have a lot of suspension travel there.

Rear shocks don't exactly look factory original either, so someone has been at the suspension...

P.S. Nice bike, good to see some colour.
Any pics anywhere of your siamesed exhaust ?
Good to see at least one example has survived, must be quite rare ?

Cheers.


As requested, here's some pics of the exhaust:






And while I guess it is possible someone cut down the stanchions, chamfered the top, retapped them, cut down the springs, cut down the damper tube and rethreaded - the obvious question would by 'Why'??

The rear shocks, obviously not the originals, but are the standard 12" center-to-center length. My yokes are not stamped for sidecar, but I was also wondering if at some time the rest of the fork assembly was from a sidecar unit. I actually have a pair of headlight ears for the sidecar forks, they are shorter overall than the standard ears, so was thinking the rest of the forks may have been also. The sidecar yokes/forks were set at a reduced rake, which would have needed the shorter fork assembly to maintain the same ride height. So maybe that's what I actually have, a mix of sidecar parts with standard yokes. Hoping someone who knows more than I do can resolve the mystery!


Peter B.
Re: Stanchion Length [Re: Peter B.] #359766
02/24/11 3:08 am
02/24/11 3:08 am
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HolmeSlice Offline
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I don't have the exact lengths with me now, but Manx tubes are approx 1" shorter than short F-bed tubes to accommodate the dropped top triple clamp. And Seeley tubes are 1" shorter than Manx, to accommodate the shorter steering headstock. So perhaps you have a set of these tubes.

Is your top clamp dropped?


Last edited by HolmeSlice; 02/24/11 3:10 am.



Re: Stanchion Length [Re: HolmeSlice] #359779
02/24/11 3:48 am
02/24/11 3:48 am
Joined: May 2006
Posts: 192
Lynchburg, VA.
Peter B. Offline OP
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No, top clamp (yoke) is just a standard yoke. I'm not familiar with the Seeley tubes, or what benefit they may have provided, but I agree mine are shorter than even the Manx tubes.

Thanks for the input guys, it's s strange combo it seems I have...


Peter B.
Re: Stanchion Length [Re: Rohan] #359799
02/24/11 8:36 am
02/24/11 8:36 am
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bromley uk
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norton bob Offline
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Bike looks fairly standard appart from, chainguard,Exhaust rings are from later bike,coil is facing the wrong way,gear indicator and set screw missing,tool tray missing,front motor mount cover missing.Later type silencer fitted but has a better line to it than many achieve.Control cables too long, I'm sure you will get it sorted! cant see a rectifier.Later tank with norton flashes missing.Later rear units with covers missing.Speedo drive normally followed lower frame tubes.Later saddle shape ,rear light mount usually enclosed type.Non SS bikes usually had raised bars.

Last edited by norton bob; 02/24/11 8:41 pm.
Re: Stanchion Length [Re: Peter B.] #359832
02/24/11 2:34 pm
02/24/11 2:34 pm
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Hamilton, Mass. USA
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Dave Comeau Offline

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Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......

Stanchions DO NOT affect ride height. unless they are so grossly over lengthe that it is bottomed out at normal sitting position. Such as matchless fork legs in a featherbed assembly. 2c


dynodave
BSA 3 1961-1963
Ducati 3 1992-2002
Norton many 1951-1975
87 Serv-Equip 100HP MC brake dynamometer,
Re: Stanchion Length [Re: norton bob] #359894
02/24/11 8:56 pm
02/24/11 8:56 pm
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Posts: 192
Lynchburg, VA.
Peter B. Offline OP
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Peter B.  Offline OP
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Originally Posted By: norton bob
Bike looks fairly standard appart from, chainguard,Exhaust rings are from later bike,coil is facing the wrong way,gear indicator and set screw missing,tool tray missing,front motor mount cover missing.Later type silencer fitted but has a better line to it than many achieve.Control cables too long, I'm sure you will get it sorted! cant see a rectifier.Later tank with norton flashes missing.Later rear units with covers missing.Speedo drive normally followed lower frame tubes.Later saddle shape ,rear light mount usually enclosed type.Non SS bikes usually had raised bars.


Have already locate and obtained the proper pieces - tank, seat (NOS), rear lamp unit (NOS), mudguard, etc. I just need to figure out the fork situation, and the long slow rebuild can commence...oh, and also obtained an original enclosed chaincase as came on my bike. Mudguards will be chromed as per the original build data, and the bike was ordered with the flat bars!

Thanks Bob.


Peter B.
Re: Stanchion Length [Re: Dave Comeau] #359895
02/24/11 8:59 pm
02/24/11 8:59 pm
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Lynchburg, VA.
Peter B. Offline OP
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Originally Posted By: Dave Comeau
Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......

Stanchions DO NOT affect ride height. unless they are so grossly over lengthe that it is bottomed out at normal sitting position. Such as matchless fork legs in a featherbed assembly. 2c


So Dave - are there any advantages/disadvantages to the shorter stanchions? Any idea why my setup is not 'standard'? Do the shorter stanchions actually give more travel than the standard ones that are 2" longer?


Peter B.
Re: Stanchion Length [Re: Dave Comeau] #359909
02/24/11 10:24 pm
02/24/11 10:24 pm
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Rohan Offline
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Originally Posted By: Dave Comeau
Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......

Stanchions DO NOT affect ride height. unless they are so grossly over lengthe that it is bottomed out at normal sitting position. Such as matchless fork legs in a featherbed assembly. 2c


Well yes, but Manx alloy fork sliders are forged (not cast like the road bike ones), because with so little engagement of the fork tubes inside the sliders on short fork tubes, the sliders were found likely to fail or split....

So there obviously is a limit to how short the stanchions safely can be... ?

Re: Stanchion Length [Re: Dave Comeau] #359914
02/24/11 11:01 pm
02/24/11 11:01 pm
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Originally Posted By: Dave Comeau
Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......

Stanchions DO NOT affect ride height. unless they are so grossly over lengthe that it is bottomed out at normal sitting position. Such as matchless fork legs in a featherbed assembly. 2c


Don't long fork tubes usually have a long spring/damper setup, and short tubes a short spring / damper setup ??

Re: Stanchion Length [Re: Peter B.] #360000
02/25/11 1:25 pm
02/25/11 1:25 pm
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Dave Comeau Offline

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Originally Posted By: Peter B.
Originally Posted By: Dave Comeau
Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......

Stanchions DO NOT affect ride height. unless they are so grossly over lengthe that it is bottomed out at normal sitting position. Such as matchless fork legs in a featherbed assembly. 2c


So Dave - are there any advantages/disadvantages to the shorter stanchions? Any idea why my setup is not 'standard'? Do the shorter stanchions actually give more travel than the standard ones that are 2" longer?


The shorter staunchon will then hold the lower bush higher in the fork leg. It would "top out" easier and not bottom out so easy and possibley not bottom out the bush against the leg bottom... but rather coil bind the spring first.
I would guess that a normal fork/staunchion bush would ride allowing 2/3 of the travel until bottoming out(4") and 1/3 until toping out(2").
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: Stanchion Length [Re: Dave Comeau] #360002
02/25/11 1:37 pm
02/25/11 1:37 pm
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Peter B. Offline OP
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Originally Posted By: Dave Comeau
[quote=Peter B.][quote=Dave Comeau]Ride height (for internal springs) is the length of the spring plus the length of the particular damper body used that the spring sits on......


The shorter staunchon will then hold the lower bush higher in the fork leg. It would "top out" easier and not bottom out so easy and possibley not bottom out the bush against the leg bottom... but rather coil bind the spring first.
I would guess that a normal fork/staunchion bush would ride allowing 2/3 of the travel until bottoming out(4") and 1/3 until toping out(2").
http://atlanticgreen.com/forks.htm


Thanks all. Dave, the measurements on the page you link to are quite helpful, that's excatly what I needed.

So it seems I have Seeley stanchions - can anyone give me some info on these, why someone would have put them on, etc?


Peter B.
Re: Stanchion Length [Re: Peter B.] #360033
02/25/11 5:11 pm
02/25/11 5:11 pm
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Originally Posted By: Peter B.

So it seems I have Seeley stanchions - can anyone give me some info on these, why someone would have put them on, etc?


The usual reason for fitting shorter fork bits is in racing - to have stronger springs and stronger damping for a firmer ride. And less suspension movement, for less varaiation in steering geometry.

Same may apply if a sidecar comes into the picture...

Re: Stanchion Length [Re: Peter B.] #360034
02/25/11 5:19 pm
02/25/11 5:19 pm
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Originally Posted By: Peter B.


And while I guess it is possible someone cut down the (Commando) stanchions, chamfered the top, retapped them, cut down the springs, cut down the damper tube and rethreaded - the obvious question would by 'Why'??


Thats doing it the hard way ? !!

Machining a groove for the circlip on the lower end, and drilling a few holes for the slected damping allows your choice of dampers - remember Norton dampers are only one way, not 2 way like the racers use.

And Commando tubes are hard chromed, so no rust under the covers, and wear better as well ?

Cheers.

Re: Stanchion Length [Re: Rohan] #360038
02/25/11 5:22 pm
02/25/11 5:22 pm
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Originally Posted By: Peter B.

And while I guess it is possible someone cut down the (Commando) stanchions, chamfered the top, retapped them, cut down the springs, cut down the damper tube and rethreaded - the obvious question would by 'Why'??


P.S. Its quite possible the reason why you have such short fork tubes is that someone has cut down YOUR forks as your above, so you need to ask them "why ?".

If you have sidecar fork yokes bits with it though, sidecar use may come into it. Any sign of sidecar clamps or brackets on the frame or frame tubes ?

Cheers.

Re: Stanchion Length [Re: Peter B.] #362123
03/09/11 7:07 pm
03/09/11 7:07 pm
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Originally Posted By: Peter B.
I stripped down the forks tonight as part of my 1960 99 restoration. Since the stanchions are somewhat rusty where they are covered by the shrouds(as usual), I was thinking of replacing them. Here's my quandary - when I look at the Norvil site, it lists the length as 21 7/8" for the short Roadholders - yet mine measure 19 7/8"! Was 1960 a special year, are the stanchions from a different model for some reason, or any ideas? What is the 'correct' length? The NOC sells them too, but doesn't list the length.


This may either help or confuse:

1964 - Nos. 107388 to 110774 : Atlas Scramblers G.15C.S./N and G.15C.S./M : Approx. 1000 built





All these machines used a new frame similar to the G.12 C.S. duplex type with bolt on rear subframe but were fitted with a redesigned malleable steel headstock machined to accept Norton forks and front wheel. The robust swinging-arm was of the Matchless type, but also redesigned to accept a Norton rear wheel.





The arm pivoted on a hardened steel hollow spindle, the outside diameter of which ran in phosphor-bronze 'oilite' bushes pressed into large lugs on each side of the front of the fork. This spindle was supported by its centre portion in a sturdy single cast lug which was pinned and brazed to the vertical tube forming the rear section of the main frame, the spindle being locked in position by way of a cotter. The front forks used stanchions which were 2" longer than the Featherbed version and had special 'Teledraulic' type two-way damping and external springs hidden by steel cover tubes in preference to rubber gaiters, along with standard Roadholder alloy sliders. The forward engine mounting lugs were positioned to accept the latest twin carburettor version of the Atlas engine. The frame/engine numbers followed the Norton system (as did all subsequent hybrids).


Some good information can be had here:http://www.motorbyte.com/norton/Report.html

Art



Last edited by bmwr90s; 03/09/11 7:08 pm.

1969 XLH
1973 Norton Commando
1991 FLHTC W/SIDECAR
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