An Unholy Union V: DRZ forks on an Airhead

Discussion in 'Airheads' started by Ras Thurlo, Jun 28, 2014.

  1. infinityedge

    infinityedge Long timer

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    Does anyone split the spacers? I thought everyone put it all on top. I did.

    D3DFA561-CAAB-4462-8A9C-A84A99B4DC86.jpeg
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  2. Motopsychoman

    Motopsychoman Not a total poseur Supporter

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    A tip for folks working on their DRZ forks. Getting the nut at the top of damper rod on and off has been a pain using all the different 17mm wrenches I own, even some pretty slim ones.

    For $6 I went and bought a 17mm bicycle cone wrench, like this
    [​IMG]
    Just 2mm thick and slides easily above or through the spring.
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  3. Jim K in PA

    Jim K in PA Long timer Supporter

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    I split mine upper/lower.
  4. infinityedge

    infinityedge Long timer

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    My stem flared at the bottom so that the bottom bearing had a snug press fit like the OP while the top was of constant diameter for quite a bit.
  5. Screaming Chicken

    Screaming Chicken Long timer

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    I would assume you’d put the spacers all on top so the lower triple isn’t unnecessary low, to leave more room for suspension travel.
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  6. Jim K in PA

    Jim K in PA Long timer Supporter

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    The spacer is about 10-12mm total thickness, so 6mm loss in suspension stroke is not likely to be noticed.

    I also shortened my forks by 75mm.
  7. AntonLargiader

    AntonLargiader Long timer

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    If you are trying to retain use of the stock centerstand, and want the most travel possible without the sliders hitting the lower triple or the boots crushing, you will not want to give up any space like that. I can't think of any benefit to using a lower spacer when the forks have such an excess of travel..
  8. Jim K in PA

    Jim K in PA Long timer Supporter

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    Really? 5mm of increase length/height at the contact patch of the front wheel, some 200+mm forward of the contact point of the center stand, is really going to make or break the usability of the CS? I deleted the CS on my bike, so it was not a factor. And location of the spacer(s) has zero bearing on the available travel. The spacers keep the upper and lower clamps at the same distance as they were if the forks were mounted on a Suzuki, no? Depth of engagement of the fork tubes in the clamps will determine any change in upward travel.

    It's been a few years, so I had to look back a ways, but the reason for splitting the spacers was upper bearing engagement on the stem.

    Here: https://advrider.com/f/threads/an-u...ks-on-an-airhead.989832/page-33#post-32063133
  9. AntonLargiader

    AntonLargiader Long timer

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    If the whole "if you want to retain use of the stock centerstand" part doesn't apply to you, then what I wrote doesn't apply to you.

    Pretty sure I enumerated the geometry at the time, but basically the total distance from the head tube down to the front wheel is what matters to the frame height. On the bike I did, I was at slightly less than OEM travel (maybe 205; stock is 210~215) to keep the fork slider from hitting the lower triple and keep the centerstand useful. Spacing the lower triple down just comes straight out of the travel if you have an additional constraint (the centerstand in this case). If you're fine with that for your build, fine. Just saying that it comes out of the travel unless you don't care about the total height.

    You had no CS and the height didn't matter. Not a big surprise that you aren't on board. How close are your sliders to the lower triple under full compression, like with no springs?
  10. Jim K in PA

    Jim K in PA Long timer Supporter

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    No idea how close the sliders might get to the lower triple at full stroke with no springs, but is that even relevant with an assembled fork? I don't jump the bike, so never exercised the forks to full travel. I think my springs will stack solid before the slider hits the clamp.

    Agreed that the lack of a CS on my bike makes the point moot, but I still suspect the delta in height at the CS contact points with an extra 5mm at the front wheel is going to be in the 2-3mm range. At this scale, the amount of gas in the tank will have as much impact.

    The link I posted is from 4 years ago. I think I mounted the forks late in 2016. Been a while, but the primary point I was trying to make in counter to your statement that there is no benefit to a lower spacer is that the benefit is better engagement of the upper bearing inner race on the stem. This condition may likely vary with the year of DRZ stem.
  11. Screaming Chicken

    Screaming Chicken Long timer

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    The centerstand isn't even the most relevant thing.

    The forks connect the front wheel to the headstock. To make the geometry of the bike work the headstock needs to be a certain distance off the ground. If you put the spacer underneath you're making part of that distance rigid when it could've been suspension travel. It's that simple.

    Is it a disaster if it's already set up that way? No. Is it worth tearing it all apart again to redo it? Nahh probably not. Are you going to miss 6 mm of suspension travel? That's up to you, some people might. But if you have a choice between suspension travel X or suspension travel X minus 6 mm, why limit yourself?
  12. Screaming Chicken

    Screaming Chicken Long timer

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    Incidentally, one reason to put a spacer underneath might be to help the lower triple clear the PD fairing support bracket. Or possibly to get a bit more steering lock before the lower triple hits the frame. No idea if that makes any difference but I could see those might be worth trading against suspension travel.
  13. AntonLargiader

    AntonLargiader Long timer

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    For some people. Every fork has some kind of bottoming stop. Ideally it is the hydraulic bottoming cone built into good forks (the stock R100GS fork has this, as does the DR-Z). A poorly chosen spring will become the bottoming stop instead... I have seen that and IMO it's pure negligence on the part of the person specifying the spring. Or the bottoming stop could be the fork seals crashing into the lower triple.

    The one I built was for a guy who rides aggressively enough to be regularly bottoming out his R100GS and his F800GS. I had to do it right and make sure the bottoming cone was in play. Relying on never bottoming out the fork is not a sound plan.
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  14. Jim K in PA

    Jim K in PA Long timer Supporter

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    Understood, and eminently reasonable given your situation (and profession!)

    Each build, and rider, is different. I made the decision to split the spacer based solely on the geometric challenges before me. It works quite well for my purposes. I was not attempting to be didactic in sharing what I did and why, just answering the other builders question.
  15. AntonLargiader

    AntonLargiader Long timer

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    Well, if I thought getting the bottoming right was exclusively the purview of pros or something like that, I probably wouldn't have posted. IMO everyone needs to assume their suspension is going to bottom out at some point. So if you're custom building a shock or a fork or a complete suspension assembly, you should know what the hard stop is going to be when it happens. If nothing else, getting it wrong can be expensive if wheels hit nicely painted fenders, swingarms hit frame parts, heim joints go beyond their normal flex angle, etc.
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  16. Jtdunn92

    Jtdunn92 Been here awhile

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    Question for you guys. Does it matter if my wheel is off center by 1 - 2mm? I tried centering it but the brake disc gets a little too close to the forks for comfort. What have others done?

    49E6424C-724E-4F21-B8F1-8FED1D731122.jpeg AFA422CC-96FB-4A2B-93C5-67BB4F165C81.jpeg 470CF015-37E0-4657-A436-906A25965536.jpeg 1A986332-D5E8-43BE-9413-9C31259C1696.jpeg
  17. bleaknessengine

    bleaknessengine Been here awhile Supporter

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    i moved the run over by re-dishing the wheel, tightening spoke tension on one side and loosening it on the other, 1/4 turn on each spoke at a time. i had to go around the wheel quite a few times, but since i laced it up originally it was totally my fault. now it’s mostly in the center haha.
    if you move the hub, wrong that interfere with your caliper engagement?
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  18. AntonLargiader

    AntonLargiader Long timer

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    Yes, but since that is probably controlled by custom pieces anyway, it's not necessarily more correct to move the rim than move the hub. Depends what is out. Personally I'd want the hub and rim centered first, then make the brakes line up around that.
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  19. Jtdunn92

    Jtdunn92 Been here awhile

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    Got it. I’ll have to offset the rim because the hub is as far as it can go. It’s not an issue of the caliper, if the hub goes any further left the disc will make contact with the fork leg.
  20. Motopsychoman

    Motopsychoman Not a total poseur Supporter

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    How much clearance is there between the floater pins and the leg? On my Sertao/DRZ setup, I've only got about 1.5mm clearance between the rotor bolts and the axle attachment part of the fork and I'm okay with that.

    Also, the black hub and rim looks nice.