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Discussion Starter · #1 ·
Hey ya'll,
I'm piecing together a British front end to run on my panhead for a change from the stock springer. I have a mixed bag of parts and no knowledge of anything British.

Basically I've got fork tubes and legs for the late 60's early 70's front ends. Steel legs. Along with the damper setup with aluminium shuttle valve. I also have a set of early pre-unit legs that I would like to use instead of the later legs. I also have earlier pre unit trees with the built in rake.

Does anyone happen to know if the later fork tubes + damper setup can work with the earlier pre-unit legs and trees? The tubes seem to fit nicely in the earlier lowers as well as the trees but haven't tried setting up the damper etc yet.

Thanks.
 

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can't remember details of both set ups but why replace one fork tube with another; a tubes a tube, or are they a different length?.
As for fitting in the top clamp, did the earlier forks butt up where as the later ones had a pinch bolt in the top clamp?. Or was it the other way around ?. Can't be arsed to go out to the garage and look but if you have them in front of you it should be obvious.
I would say i'm surprised that the fork are the same diameter, i do know my pre unit forks unbraced get a serious case of the Chubby Checkers, as in - 'lets twist again, like we did last summer'
 

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Discussion Starter · #3 ·
I only have the fork tubes for the later legs. I am just trying to see if I can save some coin by using what i've got rather than having to purchase earlier model fork tubes.

The later tubes that I've got have a taper at the top that seems to fit correctly with the earlier top clamp so I think they both must have used the same taper.

Oh yeah no doubt, they seem pretty noodley. The 33.4 front end I have on my sportster is the same, lots of flex.
 

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yea mine twist too so thats good to know yours do it too thunderbird.
All the parts books are online you can cross reference part nos. maybe
 

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Triumph Conical or Disc for tubes are larger diameter that the steel slider fork tubes so the early trees would need to be machined and the steel sliders would not work. I have seen the conical dampers adapted to a Norton fork so should be possible to adapt to the early Triumph fork tubes.
 

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/\/\/\ my failing memory, of course later forks were beefier. i have this rather clumsy looking brace. doubles as a rain catcher and i tell people the clamps give much needed down force at speed. i keep meaning to do some cut aways on the side of the brace to put it more in line with the forks, but then it may lose ridgity. Maybe i'll just ride the thing. Wheel Tire Fuel tank Plant Vehicle
 

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Discussion Starter · #7 ·
The later legs I am talking about are still steel legs, with external springs. The fork tubes that came in those legs fit inside the earlier pre-unit steel legs and it seems the bushing fits nicely too. I'm just not sure if there's something else I'm missing. This is the later style forks I am referring to.
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Thunderbird, that fork brace is ... unique. It looks multipurpose by design, like you could whip it off and put it to use as an architectural model of a Brutalist amphitheater or, if nothing else, in a bar fight.
 

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I have forgotten so many things but I am sure that I remember that the fork tubes by themselves are the same from preunit to unit until model year 1970 on the 650s
What you are missing are the internal springs obviously. Many years ago Forking by Frank had a kit to convert the external spring unit forks to the smooth internal spring preunit look. It consisted of slim preunit seal holders and internal springs and spacers.for extended front ends.
 
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