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Thread: Fork internals upgrade report.

  1. #11

    Re: Fork internals upgrade report.

    Thanks for the thoughtful comments.

    Yes agreed, it would be great if valves could be adjusted without removal. Instructions say, tune by half-a-turn at a time. Plan is to make adjustment then evaluate to ensure direction is correct.

    I must re-read the manual but as I recall, there a number of individual adjustments possible.

    1/. Rebound damping. Increasing or decreasing oil viscosity adjusts rebound damping. As rebound seems good, I'll probably elect to leave it alone and concentrate on other settings.

    2/. Compression damping. This is in 2 parts, high speed and low speed. The low speed damping seems perfect but high speed damping is slightly too much. Plan is to reduce valve spring preload by half a turn.

    3/. Air-volume-above-oil. This air volume controls how much forks dive. I already tried draining a small amount of oil from each side but it didn't give the desired result (and it was an easy thing to try).

    4/ Fork spring strength and preload. Spring weight was calculated by Racetech and it seems good.

  2. #12

    Re: Fork internals upgrade report.

    I used the progressive suspension springs in my bagger, left the stock springs in the wife's deuce. I'm still impressed with the improved ride after 18 years...
    64 Duo-Glide

  3. #13

    Re: Fork internals upgrade report.

    Update:
    Finally got to adjusting the High Speed compression damping. I elected to reduce H.S. valve spring preload by 3/4 turn. I road tested without nacelle and front fender. The response was excellent but not enough so I reduced preload another 1/2 turn.
    I understand better now that I've done the adjustment. The issue was hydraulic lock of the forks whenever I hit a big sharp bump the forks couldn't move quickly enough or at all. It was as though the forks were solid for that split second.
    I've decided to reassemble everything and try it out over a number of weeks. I've got a good improvement so worth the few hours work. All other settings are good.
    Hope this is interesting.

    Pic during test...

  4. #14

    Re: Fork internals upgrade report.

    Race tech should do a cutaway fork video showing the valve in action, I thought about making a clear tube gauge that could be screwed into the drain hole, just to see where the actual oil level is with 7oz. in the slider. And if the valve actually is within the oil level.
    64 Duo-Glide

  5. #15

    Re: Fork internals upgrade report.

    Agree about fork cutaway video. An animation would be perfect. I bet they've thought of it but cost was prohibitive.?

    Like your oil level idea in principle. At the risk of telling you things you already know... In my case I collapse the fork down and measure oil level from the top.
    The top cap vents are blanked off so air above the oil gets compressed as forks dive. The amount of air above oil is also an adjustment parameter. Racetech spec'd 150mm oil level from top, fully collapsed without spring IIRC.
    The valving is completely covered even on full extension as can clearly be seen from above.

    Where I'm up to with dialing in the setup.... I moved to the lighter valve springs. Once I did, I realized I was never going to get a perfect setting with the earlier/heavier ones. As it is I'm contemplating reducing valve spring preload another half turn. Easy to get confused with this stuff so am taking my time with the decision. Doing a number of rides in different conditions then making my adjustment choice.
    BTW, I found it much easier/quicker to remove the nacelle then the top tree. Unscrew the caps in situ. Bike needs supporting of course.
    Also my top caps differ from the Racetech drawings in that the allen head blanking plugs screw-in from above. They screw into a counterbore sealed with a copper washer. This means they are removable from above to change oil.

    It's coming along. My grin is getting bigger...

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