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  1. #1
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    Default Dumb fork questions, Modifying 41mm HD forks or others?

    Okay, looked around and didnt see much directly addressing this. So, see these forks?

    Click image for larger version. 

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    Apparently these are 41mm HD forks, came on quite a few models and years, but here is where I am going.
    On vintage style street trackers, the original 50s and 60s bikes had pretty crappy suspension. Most people who race keep the frame and the engine and run better suspension.
    (What the rules allow.. IE:Travel is a major sticking point)

    So what was popular were Betor and Cerrani forks. They made several configurations and sizes, as well as dirt-off road and road racing.

    The HD wide glide 41mm look like the cerrani road race forks. Now Cerrani did make bigger forks than the old standard 35mm forks but rare and hard to find. As well as $$$$$$$

    So looking online I see upgraded springs, Race tech cartridges and some other parts, But with so many big twins parted out, It might make a cool upgrade for a street tracker. There is variables of course, setting up trees and wheels and brakes, But anyone seen other builders using modern Forks like this to get that vintage look but much better performance???

    Seems many think the Yamaha R6 Forks are the best out there, but the word is out and they often sell quick, But they dont have that classic look either. I admit fashion does not over rule function, But looking for options with the right look but affordable performance.

    *Clearly redialing in a vintage bike weight, rebound and damping vs a Bagger with yer old lady and all your luggage notwith standing.

    Anyrate...looking for input.

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    Not sure exactly what your asking here Doug
    Did you mean to post this in the Brit bike section?
    I think the 39mm Harley front end on a triumph is definitely an upgrade.
    Better match visually than the wide ass 41 trees
    And they are more performance orientated than the 41s too.
    Dual disk, adjustable damping and preload were all available stock.
    Add the aftermarket and the only way you'll get better is something off a crotch rocket.
    That being said, I think 70's and 80's dirt bike legs look a treat on a narrow rigid bike as well.

  3. #3
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    Quote Originally Posted by Sky View Post
    Not sure exactly what your asking here Doug
    Did you mean to post this in the Brit bike section?
    I think the 39mm Harley front end on a triumph is definitely an upgrade.
    Better match visually than the wide ass 41 trees
    And they are more performance orientated than the 41s too.
    Dual disk, adjustable damping and preload were all available stock.
    Add the aftermarket and the only way you'll get better is something off a crotch rocket.
    That being said, I think 70's and 80's dirt bike legs look a treat on a narrow rigid bike as well.
    Sorry I was not more clear. This is not a British or HD post,. Its about using modern forks on a vintage style bike. Repurposing parts that look the part but more accessible-economical-but as good or better performance.

    You can hold out, spend the money when up for sale or ebay and buy the real things, But if you can repurpose something like HD 41 mm forks for low prices,, it could be an option.

    Now, to be clear, that Triumph chopper is using wide trees. Thats fine on a chopper but not what I am talking about. On a Street tracker (Asian-American-European) you would use narrower trees of some sort. Either custom made or mix & match something.

    Here is a few photos of typical Cerrani forks used on all kinds of bikes, but popular choice for desert sleds, road racing, MX etc... Betors is another one and very similar in appearance.

    Click image for larger version. 

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    Double Knockers and Single Knockers road race forks. (The lugs on the sides defines the term)

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    Single Knocker Roadrace Cerrani.

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    MX and Dirt type Cerrani forks. The tabs are often milled or shaved off in some cases.
    But some creative fork stiffening braces often used and line up to those tabs as well as mount a fiberglass or alloy front fender.

    So, occasional deals come up, but good cerranis and Betors are not cheap. They make NEW versions and they are very nice but $800-2500 depending on source and specs.

    So, lets say you are at a ABATE swap meet, and you see some 41 MM HD forks for $50 -100? What I want to know is has anyone reconfigured them to look like these Cerranis? On your HD Sprint-Aermacchi or Triumph TT or your BSA Hornet or your Honda Elsinore?

    So, I am building some street tracker projects and selling one and the guy is looking for alternatives,

    So, just for shits and grins, heres 2 examples. Now these are trackmaster frames, but We got that covered as well. (*Triumph and BSA OIF 1971-> bikes frames are VERY SIMILAR to a trackmaster.)

    Click image for larger version. 

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    xMPRx solved the problem nicely. Check out his jig.

    http://www.chopcult.com/forum/showthread.php?t=50726

    Rubbermount Sporty top triple clamps don't use bushings and their riser holes are sized for bolts instead.
    Last edited by farmall; 05-08-2020 at 1:43 PM.

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    Quote Originally Posted by farmall View Post
    xMPRx solved the problem nicely. Check out his jig.

    http://www.chopcult.com/forum/showthread.php?t=50726

    Rubbermount Sporty top triple clamps don't use bushings and their riser holes are sized for bolts instead.
    Thats very helpful info, whether using 41s on a Sporty or setting up a custom front end period. The alloy sporty trees are decent on their own and polish up or modded are decent trees. Thanx for that.

    Now,, if I could just get feedback on the 41mm forks such as "I did XYZ mods and products and these still handle like SH*T!" Or... "Huge improvement in damping and rebound over my previous forks, and with XYZ products its best front end I could hope for, Rides like a dream!"

    Since most users of the 41mm forks are on a big twin and likely a loaded down bagger, the ride reports are likely subjective, vs,, "I put these on my Rickman, adjusted for the lighter bike, entered the Barstow to Vegas MX and just glided over the terrain"

    or... "I rode my Bagger to the lifestyle Bros club campout and with the new cartridge emulators, progressive springs and BelRay multi vis fork oil, I didnt spill my coffee once and Buffys tush riding behind was comfy the whole way"

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    They certainly won't handle like shit since they're just typical forks. Spring rates etc will be your lookout but they work on 600lb Sporties so they're reasonably close. It's pretty hard to fuck up sliders and tubes.

    Any spring of correct diameter would do for experimentation along with PVC preload spacers. You're wildly unlikely to find anyone else who bothered to do what you're contemplating because the money isn't serious to the wealthy old collectors and their autism will push most to spend more on the real deal for fap value. Those guys have CNW Norton money and that is far from a poor man's hobby.

    For as little as you'd have in a test front end (not much) you may as well buy the parts and start cutting metal. You can always sell the result to someone with a Harley and probably for a profit. Study Wide Glide fork tube lengths. I've no Wide Glide tubes to inspect but it may be easy to shorten them from the bottom vs. dealing with the top by measuring the external dimensions, turning the tube down to harvest any insert etc.

  7. #7

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    D,

    Those 1 5/8" forks (41mm) appear LARGE compared to the Itaian and Spanish forks, so I think visually you would be disappointed with the looks. Plus, the HD forks are HEAVY in comparison to say, a Cerianni. The lowers at least are widely available, since so many were replaced with chrome ones. Used parts vendors have bails of them. The tubes are not so common used, naturally. The damping on the newer forks is typical Showa, but there are some HD models with a cartridge fork on the left and a conventional fork on the right, but set up for a heavy bike, of course.

    The newer tubes have an insert swaged in at the bottom, so shortening them from the bottom is not so easy.

    Jim
    Last edited by JBinNC; 05-10-2020 at 5:41 AM.

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