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Thread: 06'x-09'xt Fork Rebuild

  1. #1
    Senior Member TheWood's Avatar
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    06'x-09'xt Fork Rebuild

    I just acquired my 1st Buelly(06' XB12X, 3rd owner), and am pretty excited about it. All is good, except the front forks are way weak/soft, and will near bottom out with average braking. So I decided to order the HyperPro lowering kit(front and rear coil and springs) as I'm 5'-8", and it's a bit tall even with the low seat that the previous owner installed. So, getting to my point here... when I disassembled the forks, I discovered that the PO installed 09' XB12XT front forks, so now the HyperPro front springs are incorrect for these 09' XT forks(390mm). The place I ordered from is thankfully taking back the front springs (480mm)from the 06' kit, and instead recommending spring #1079(350mm) which is for the XB R/S apparently, and using a 40mm spacer. My question is this; is it true that the XT forks are already 1" lower than the 06' XB12X forks? And can, or should I go a bit lower to get closer to the ground, or will the additional lowering in the front upset balance/handling? Remember, the Hyperpro lowering kit already gave me my 1" lower in the rear. This is all new to me, but mechanically inclined enough to get it sorted once I get the right plan.info. I've read through a lot of the forum threads here, but still have these questions. Any help is very appreciated.

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    Senior Member Cooter's Avatar
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    If you have to lower the bike, it is important to keep it as level as possible front to rear.
    A 390mm spring is the same as a 350mm + 40mm spacer, and you can adjust the length of the spacer for a height change without it changing your spring rate.

    It is your weight (fully geared up and with everything you normally carry) that affects the spring rate you need (sag). Although large changes in spring rate affect suspension action (obviously) it is fork damping (adjustments and oil weight) that will change the dive characteristics you don't like.

    Have fun getting her dialed
    Spring rate first to get the right sag, then damping adjustments.

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    Senior Member TheWood's Avatar
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    Thank you for reply Cooter; great info. Apparently the OEM progressive spring on an XT starts @ .68kg./mm. The proposed 350mm progressive spring w/ 40mm spacer would be .76-1.22kg./mm. So this spring with slightly higher rate will not sag as much and perhaps I may want a bit shorter spacer? Is that what you mean by dialing it in? And am I assuming right, that their supplied spacer goes down on the bottom of spring(towards the wheel)? I'd love to get this right on the first shot. I'm about 270# w/ all my gear on. Perhaps my weight will get me all the sag that I need, Ha.

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    Senior Member outthere's Avatar
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    Hey Wood I'm in Cloverdale if you need help.

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    Senior Member TheWood's Avatar
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    Wow, thanks for the offer! The wife and I stop in for breakfast on occasion at the Hamburger Ranch when we head into the city. Well, it turns out my fork problem just got worse. Finally got around to cleaning all the parts, taking apart the fork caps,pushrods,etc., and the PO stripped the threads on the internals of the caps; over cranking the preload and rebound adjusters. And is no doubt why I had such terrible dive. Now I'm wondering if it can be fixed w/ helicoil,time-sert,or form-a-thread type repair. What are the odds I'll find the needed fork caps and pushrods somewhere so I don't have to do that type of repair?
    Quote Originally Posted by outthere View Post
    Hey Wood I'm in Cloverdale if you need help.

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    Senior Member Cooter's Avatar
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    All FOUR sets of threads are stripped!? Are you sure they aren't just corroded and need a soak? Holy heck thats terrible

    I have seen rebound screws messed up by improper re-assembly quite a bit, but the pre-load screws are huge! Either way. I'd go shopping for bent forks on e-bay. Buell fork caps with the same diameter should interchange, and the later bikes have a different pre-load screw. I heard those also interchange with the old style from a reputable source, but have NOT tried it myself.
    Last edited by Cooter; 09-21-2020 at 05:22 PM.

  7. #7
    Senior Member TheWood's Avatar
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    Yeah, I wish it was just cleaning up buggered threads, but dude gorilla'd them not knowing the repercussion. I knew when I bought the bike that the forks had issue, but thought I would just need to clean,rebuild w/new bushings & seals, and add SAE15. Now I'm seeing why I got such a good deal on it($2,400.)! I'll see if I can get some pic.'s. I'm new here and am not real savy w/ adding pic.'s,etc.
    Quote Originally Posted by Cooter View Post
    All FOUR sets of threads are stripped!? Are you sure they aren't just corroded and need a soak? Holy heck thats terrible

    I have seen rebound screws messed up by improper re-assembly quite a bit, but the pre-load screws are huge! Either way. I'd go shopping for bent forks on e-bay. Buell fork caps with the same diameter should interchange, and the later bikes have a different pre-load screw. I heard those also interchange with the old style from a reputable source, but have NOT tried it myself.

  8. #8
    Senior Member TheWood's Avatar
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    I'll attempt a pic. hereAttachment 14316Attachment 14316
    Looks like the PO cranked the cap on and off w/ vise grips
    Last edited by TheWood; 09-21-2020 at 09:45 PM.

  9. #9
    Senior Member Cooter's Avatar
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    Oh my, you weren't kidding
    I wonder if 1125 parts interchange? They seem easier to get. You could look up the parts fiche on Twin Motorcycles and compare part numbers. Otherwise E-bay bent forks FTW.

  10. #10
    Senior Member Cooter's Avatar
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    Perhaps https://www.twinmotorcycles.nl/websh...parts.asp?mc=1 has new ones for you?

    #19 and #21



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