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Thread: Shorten fork 1 inch

  1. #31
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    Re: Shorten fork 1 inch

    Last edited by jspringator; 12-01-2017 at 06:22 AM.
    2000 ST1100 ABS 40,000 miles, RDL, Helibars, X-Creen on Clearview shield, lower Works shock, PR4GT with 60 series rear tire
    06 XT225 RDL, Webcams cam, Beehive racing valve springs, High compression piston, cheap motard conversion

  2. #32
    Robert RobbieAG's Avatar
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    Re: Shorten fork 1 inch

    Quote Originally Posted by jspringator View Post
    Robbie, I'd like to get some aftermarket straight springs, cut a spacer in each fork 1 inch, refill with standard fork oil and call it a day.
    That was pretty much my intention (except cutting the spacer) until I ran into trouble disabling the anti-dive. Once I decided to send the forks in, it made sense to have them rebuilt because the bike has 57k miles on it and had original seals and bushings. They would probably need to be done before long anyway. Once I was there, it was only another $150 to have them revalved, so that's what I did.

  3. #33
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    Re: Shorten fork 1 inch

    I could get Sonic middle of the road firmness springs, and not disable the and dive, not revalve, put standard 7.5 weight oil back in, and cut the spacers 1 inch. I don't think sonic requires the anti dive be disabled. In the schematic I clearly see spacer I could cut on one side, but the other is more difficult to see. Would I be able to cut/remove an inch of spacers on both sides based on your experience? I would go on and get the seals and bushings replaced while I was in there.

  4. #34
    STOC #687 dwalby's Avatar
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    Re: Shorten fork 1 inch

    Quote Originally Posted by jspringator View Post
    I could get Sonic middle of the road firmness springs, and not disable the and dive, not revalve, put standard 7.5 weight oil back in, and cut the spacers 1 inch.

    In the schematic I clearly see spacer I could cut on one side, but the other is more difficult to see. Would I be able to cut/remove an inch of spacers on both sides based on your experience?
    The first thing to consider is aftermarket springs aren't necessarily the same overall length as the stock ones, so they often require different spacers anyway. You need to take that into consideration before getting started if you change springs, you'll need to recompute the sag numbers with the new spring rate and spacer combination. And, for comparison you'll need to know the stock sag values. If you keep the stock springs and just go with 1" shorter spacers there's nothing to compute. I think that would be possible given the stock spacer lengths, but I can't say for sure.

    Regarding the spacers, on non-ABS bikes the left fork has the longer spacer that's clearly visible on your fiche reference, on ABS bikes that's the right fork. The other fork with the cartridge damper also has a spacer (at least the non-ABS version does) but its much shorter than the other one. It been 20 years since I changed mine, but I'm gonna guess the long spacer is maybe 5" and the shorter one is maybe 2". Keep in mind that because the forks are bolted together in the triple clamps they work as a pair, so you don't necessarily have to change both sides exactly the same way, its the combined difference that matters. I say that because the cartridge damper fork spacer is more trouble to change than the spacer on the non-cartridge side.

    Keep in mind though its not the fact that you have 5" to start with, so taking an inch off is possible. Its how much the spacer compresses the spring in the fork tube with no weight on the front end. If that is more than one inch, then shortening it by one inch will still compress the spring somewhat with no weight on the fork, which is what you want. On the cartridge damper side that spacer is captive between the spring and a nut at the end of the cartridge rod, same story there. When the cartridge rod is fully extended upward you need enough spacer length to compress the spring slightly with no weight on it.

  5. #35
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    Re: Shorten fork 1 inch

    As I try to think this through, if I have the springs lowered 1 inch, wouldn't it be impossible to also push the fork tubes up in the triple trees 3/4 inch because the top of the fender would hit the bottom of the triple tree?

    What am I missing?

  6. #36
    STOC #687 dwalby's Avatar
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    Re: Shorten fork 1 inch

    Quote Originally Posted by jspringator View Post
    As I try to think this through, if I have the springs lowered 1 inch, wouldn't it be impossible to also push the fork tubes up in the triple trees 3/4 inch because the top of the fender would hit the bottom of the triple tree?

    What am I missing?
    yes, TerryS already mentioned that a week ago, and you quoted it.

    For what you're trying to do there's a balance between ride height and moving part clearance. If you lower it too much, you could bash the fender on the triple tree during hard fork compression. Or, you could increase the spring rate to help prevent that from happening, but its still possible that an even harder hit on the forks could still make contact, and you'll have a stiffer ride quality all the time. That's why we cautioned against doing anything permanent to the forks, if you don't like it you're stuck with it after paying for it, and then need to find another set of forks if you want to go back.

    The other option of cutting the spacer by 1-3/4" and putting the tubes in their normal position in the tree would give you the same ride height, but reduce your available fork travel by an additional 3/4" (compared to the option of lowering the tubes in the clamps). I think the forks would bottom out without hitting the fender on the tree, so you remove that hazard. But if you can't cut 1-3/4" of spacer off and still compress the spring with no load, then you run into the issues TerryS mentioned earlier about having the fork tube extending with no spring force.
    Last edited by dwalby; 12-06-2017 at 05:31 PM.

  7. #37
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    Re: Shorten fork 1 inch

    I didn't understand he was talking about the combination.

    If I lower the forks internally by 1 inch by removing or shortening a spacer, can I still raise the forks in the TT, and if I can, by how much?

  8. #38
    STOC #687 dwalby's Avatar
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    Re: Shorten fork 1 inch

    Quote Originally Posted by jspringator View Post
    If I lower the forks internally by 1 inch by removing or shortening a spacer, can I still raise the forks in the TT, and if I can, by how much?
    hard to say for sure, you'd need to measure it. One way would be to remove the fork cap and compress the fork with no spring, and see how far it can travel upwards. That may be a little pessimistic though, it may be that the spring coil binds before the slider actually bottoms out, and limits upward movement (I suspect that's not the case, but thought I'd mention it anyway as a possibility). To measure that you'd need something capable of compressing the fork fully with the spring installed, which is not very practical, so the first measurement is probably the only one you're going to be able to perform. The next question is even though the fork tube can theoretically travel that far, will you ever encounter that much force while riding. Its a crapshoot, and depends on how concerned you are if the fender hits the triple clamp occasionally.

    What I'd do in your situation (assuming you absolutely need that additional 1") is shorten the spacer, drop the tubes 3/4" in the clamps, and put a zip tie on the upper fork tube to monitor fork compression on a short test ride. Then based on how much compression margin is left after that test ride I'd plan my next move from there. If you don't feel comfortable with the margin you see, put them back to level with the clamps and stop, you're still 1/4" lower than when you just dropped the tubes in the clamps, and it won't hit the fender with them level with the clamps. I've never tried lowering any bike, so I have little advice to give other than that.
    Last edited by dwalby; 12-06-2017 at 06:50 PM.

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