Cut down me fork springs

Discussion in 'Workshop' started by faffi, Mar 29, 2020.

  1. faffi

    faffi A.S.A.N.

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    Today, I cut down the fork springs in the Deauville, removing most of the soft sections. I was unsure what effect this would have, since the soft section would already be more or less coil bound and act more like spacers than springs with the preload I ran, but it made more sense to me than removing part of the stiff section.

    I cut the springs with a Dremel, then heated the ends to make them as flat as I could, before I ground them flat on the bench grinder, using the side of the stone. I have never tried this before, but the springs ended up square and would balance just as well as on the stock end.

    Did the springs become stiffer? Yes! The old preload, was a massive 60 mm. Doing my best to compress one fork leg with the stock spring and 60 mm of preload, I managed to use 105 of the standard 117 mm of travel. Now, with only 5 mm of preload for the cut springs - 55 mm less than before - I could only compress the fork 80 mm.

    I also filled the fork with Motul fork oil with a cSt of 57.1 (stock is 35.2) in an attempt to get some compression damping and more rebound. That did not work as well as I hoped; there is still next to no compression damping, although rebound now is more controlled - hope there isn't too much. If the front end still dive like mad, I will need YSS valves to control it. Not been able to test ride it yet (or set sag since I will need a helper for that) because I have not got around to fit the new braided brake lines yet, so the bike has no front brake.

    Cut, before grinding

    [​IMG]

    One short piece of spring, one ground flat, one yet to be ground
    [​IMG]
     
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  3. lindsaymac

    lindsaymac Can't reMember
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    I'm assuming you replaced the removed section of the spring with a spacer of equivalent length? You didn't mention it so I thought I'd ask.
     
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  4. faffi

    faffi A.S.A.N.

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    Yes, I did. 20 mm shorter, actually, because the same length gave too much preload now that the springs are stiffer.
     
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  5. lindsaymac

    lindsaymac Can't reMember
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    A quick cheap fix, I guess, but getting the proper weight springs for the job would have given you an extra 20-30mm of useable travel which could have, etc. etc. but would have cost more. So, would any sane person really outlay that extra money to improve a Deauville?

    Probably not.
     
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  6. faffi

    faffi A.S.A.N.

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    I cannot see how different springs can alter wheel travel, unless you have springs that coil bind before full travel? It is more about finding the correct spring rate for the bike/weight/environment, I reckon. This was the cheap fix for me, hope it works well.
     
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  7. faffi

    faffi A.S.A.N.

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    We rode about 100 miles today, my son and I. Although not quite PC at the moment, with the Covid-19 thing going on and the need to not put extra stress on the health care system, we rode very gently to get the risk of an accident as close to zero as humanly possible.

    The fork modifications I made worked out fantastically well! Now, instead of living very separate lives, the front and rear appear to react the same. Big or small bumps and dips, the sensation I get through my body from both ends is just about identical. The ride is somewhat firm, but not harsh, and the majority of road imperfections are filtered out before they reach me. Very, very happy about that. Comfort is improved also, with the front end much calmer and not bobbing/working nearly as much as before. I've always believed in soft damping and moderate springing for comfort, but this experience has altered - or at least widened - my view on this topic.

    The dive under normal situations is eliminated. I am bedding in the brakes, so I did not stop hard, but at least as hard as typical on my former rides. And the fork didn't even travel 3 inches from fully extended, so more than an inch less than under similar conditions before. Handling is also much more natural and neutral, most likely a result of the chassis pitching less under load.

    After the ride, with the help of my son, I got to measure sag. And this was an eye-opener! The fork had 41 mm of sag with me on it, and 28 with the bike alone. Clear indication of stiff springs. I upped the preload by 4.5 mm in order to get closer to the prerequisite 35 mm, as an experiment, but I can back that out if I do not like it.

    But the eye-opener came from the rear. The shock is stock and has done 60kkm / 37kmi. Apart from feeling a little "dry" (from lack of a better word) when coming down from a big speed bump, the rear end feels taut. Not once have I experienced the rear end continue to bounce after hitting a bump, small or big. However, the spring is incredibly soft! I am running preload 38 out of 40 - I tried 40, but that just seemed to overtax the rebound causing for a slightly harsh ride - and the bike still drops 29 mm with the bike alone and a full 57 mm with me sitting normally. That is 44% of the total travel! It is very difficult for me to grasp how such diverse setups can feel so similar. To me, at least. I reckon the shock as quite a bit of compression damping to assist the spring, which could explain the "dry" sensation the rear sometimes gives.

    Not that it matters, since what I experience means far more to me than theory or numbers. Now the bikes works, handling wise and comfort wise and, I presume, safety wise.
     
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  8. mikesbytes

    mikesbytes ~(:-))-[Oo

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    That's great that you have found so much improvement thru a hack, costing your time and not your money.

    In Australia going for a joy ride isn't currently allowed. Enjoy while you can
     
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  9. faffi

    faffi A.S.A.N.

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    It is not illegal here, but not encouraged, so this will not be frequently repeated until the situation change.
     
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  10. lindsaymac

    lindsaymac Can't reMember
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    Step 1. Pick a destination for your ride, planning an out & back route.
    Step 2. Find a friend in that area and call them to establish they need pain relief medication; Aspro Panadol, Neurofen.
    Step 3. Purchase minimum quantity from a chemist.
    Step 4. Proceed on "medical necessity" ride.
    Step 5. If stopped by police, refer Step 4.

    Nothing.
    They.
    Can.
    Do.
    About.
    It.
     
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  11. faffi

    faffi A.S.A.N.

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    It is due to solidarity with society, it is not directly illegal.
     
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