Valve springs on top of fork springs?

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  • willie
    Forum Sage
    Past Site Supporter
    • Mar 2006
    • 1836
    • Kingsport, TN

    #1

    Valve springs on top of fork springs?

    FWIW, I used the Search feature before posting this but didn't find what I was looking for. So here goes...I reassembled the forks on my 1100G today and was surprised at how little effort it took to push the cap down to get the threads started. This made me wonder if the springs could be on the weak side and if I could improve them by removing the metal tube/spacer and adding a valve spring and other spacer (PVC?) to make up the difference of the length of the metal piece that I removed. Has anyone tried this and if so was it worth while? Speaking of worth....I'm trying to address this problem with as little out of my pocket as possible.
    Thanks,
    Willie in TN
    Common sense has become so uncommon that I consider it a super power.


    Present Stable includes:
    '74 GT750 Resto-mod I've owned since '79
    '83 GS1100E (The best E I've ever enjoyed, Joe Nardy's former bike)
    '82 GS1100G Resto project
  • Nessism
    Forum LongTimer
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    • Mar 2006
    • 35788
    • Torrance, CA

    #2
    Removing the spacer and replacing it with a spring will make the spring rate go down. Think about it: you are replacing a non compressible spacer with a compressible spring.

    Your best bet is to pull out the springs and cut off about 3 inches of coils and then fashion some new PVC spacers to replace both your old spacer and the length of coils cut off. This will increase the spring rate of your forks and increase the ride height slightly as well.
    Last edited by Nessism; 07-17-2009, 07:57 AM.
    Ed

    To measure is to know.

    Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

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    Comment

    • almarconi

      #3
      You could also try a heavier weight fork oil.

      Comment

      • posplayr
        Forum LongTimer
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        Past Site Supporter
        • Dec 2007
        • 23673
        • Tucson Az

        #4
        Originally posted by Nessism
        Removing the spacer and replacing it with a spring will make the spring rate go down. Think about it: you are replacing a non compressible spacer with a compressible spring.

        Your best bet is to pull out the springs and cut off about 3 inches of coils and then fashion some new PVC spacers to replace both your old spacer and the length of coils cut off - 3" worth in my suggestion. This will increase the spring rate of your forks and increase the ride height slightly as well.
        agree with Ed ; cutting the spring down is going to increase stiffness because to compress a certain length across fewer coils requires those fewer coils to compress further. The higher compression of the remaining coils means the spring is stiffer.

        A heavier fork oil might be in order,but changing the fork oil will not compensate for static sag.

        speaking of static sag, that is what you are trying to achieve while insuring that you are getting adequate range out of the suspension. A trick used is to put a zip tie around the forks to see how much you compress the suspension during riding.

        Generally you never want to completely compress and if you only see only 1/2 the range (under spirited riding conditions) then you probably have it too stiff. There are various sources for setting static sag look at the Ohlins website for suspension tuning procedures.




        the proceedure is generic and dosenot only apply to Ohlins shocks

        Comment

        • almarconi

          #5
          I'd just spend the $60 and get some progressive fork springs.

          Comment

          • posplayr
            Forum LongTimer
            GSResource Superstar
            Past Site Supporter
            • Dec 2007
            • 23673
            • Tucson Az

            #6
            Originally posted by almarconi
            I'd just spend the $60 and get some progressive fork springs.
            Crap where is the fun in that?

            Comment

            • willie
              Forum Sage
              Past Site Supporter
              • Mar 2006
              • 1836
              • Kingsport, TN

              #7
              Originally posted by Nessism
              Removing the spacer and replacing it with a spring will make the spring rate go down. Think about it: you are replacing a non compressible spacer with a compressible spring.
              Ya know. The same thought crossed my mind last night. Duh! Now, instead of cutting 3" off the stock spring and making a new spacer, wouldn't adding a couple of inches (a valve spring) be better? My rationale being that you're increasing stiffness without giving up any compressability.
              Thanks for the responses.
              Willie
              Common sense has become so uncommon that I consider it a super power.


              Present Stable includes:
              '74 GT750 Resto-mod I've owned since '79
              '83 GS1100E (The best E I've ever enjoyed, Joe Nardy's former bike)
              '82 GS1100G Resto project

              Comment

              • jwhelan65

                #8
                Originally posted by Nessism
                Removing the spacer and replacing it with a spring will make the spring rate go down. Think about it: you are replacing a non compressible spacer with a compressible spring.

                Your best bet is to pull out the springs and cut off about 3 inches of coils and then fashion some new PVC spacers to replace both your old spacer and the length of coils cut off. This will increase the spring rate of your forks and increase the ride height slightly as well.
                That explains the the 2.5" spring that fell out of the bottom of my fork when I pulled them apart...I thought it snapped off the main spring but it clearly was added for a purpose.

                Comment

                • Nessism
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                  • Mar 2006
                  • 35788
                  • Torrance, CA

                  #9
                  Originally posted by willie
                  Ya know. The same thought crossed my mind last night. Duh! Now, instead of cutting 3" off the stock spring and making a new spacer, wouldn't adding a couple of inches (a valve spring) be better? My rationale being that you're increasing stiffness without giving up any compressability.
                  Thanks for the responses.
                  Willie
                  You want to add a valve spring on top of your existing springs and spacer? Doing so will increase preload on the existing spring, which will increase ride height, but will not increase the spring rate. Cutting out coils is the way to increase spring rate.
                  Ed

                  To measure is to know.

                  Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                  Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                  Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                  KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

                  Comment

                  • willie
                    Forum Sage
                    Past Site Supporter
                    • Mar 2006
                    • 1836
                    • Kingsport, TN

                    #10
                    Yes, Ed, on top of the existing spring and spacer. I realize that I'd be increasing the preload. That was pretty much my original intent. I just thought it best to add a compressive (but very stiff) preload instead of one thats solid. In a sense, I see it as a cheap way to make it a dual rate spring. No?
                    I guess I made the mistake of using stiffness interchangably with spring rate. Wouldn't adding preload, regardless of manner, increase the stiffness of the forks? And by stiffness, I mean the amount of effort required to compress the forks.
                    Willie
                    Common sense has become so uncommon that I consider it a super power.


                    Present Stable includes:
                    '74 GT750 Resto-mod I've owned since '79
                    '83 GS1100E (The best E I've ever enjoyed, Joe Nardy's former bike)
                    '82 GS1100G Resto project

                    Comment

                    • Nessism
                      Forum LongTimer
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                      Super Site Supporter
                      • Mar 2006
                      • 35788
                      • Torrance, CA

                      #11
                      Adding preload to the forks will make them ride higher and they may feel slightly stiffer but it doesn't increase spring rate.
                      Ed

                      To measure is to know.

                      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

                      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

                      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

                      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

                      Comment

                      • tejasmud

                        #12
                        Originally posted by jwhelan65
                        That explains the the 2.5" spring that fell out of the bottom of my fork when I pulled them apart...I thought it snapped off the main spring but it clearly was added for a purpose.
                        Joe,

                        The 2.5" spring is part of the 700's fork assembly. #8 on the schematic.

                        Unless you found 3 springs per fork.


                        Eric

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                        • salty_monk
                          Forum LongTimer
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                          • Oct 2006
                          • 14001
                          • London, UK to Redondo Beach, California

                          #13
                          More than one spring is just a way of changing spring curve, much like the progressive wind.

                          In some 550 forks I dumped the 4" additional spring & put in a 4" spacer, worked great.

                          In my opinion putting in a valve spring is a waste of time! If you want more preload add more spacer without cutting the spring. Putting in a valve spring would be like putting in less spacer just a complicated way of adding more preload.

                          Dan
                          1980 GS1000G - Sold
                          1978 GS1000E - Finished!
                          1980 GS550E - Fixed & given to a friend
                          1983 GS750ES Special - Sold
                          2009 KLR 650 - Sold - gone to TX!
                          1982 GS1100G - Rebuilt and finished. - Sold
                          2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!

                          www.parasiticsanalytics.com

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                          • posplayr
                            Forum LongTimer
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                            • Dec 2007
                            • 23673
                            • Tucson Az

                            #14
                            does anyone have any idea what the spring rate of the valve spring is compared to the fork springs? that would be the determining factor as to whether you were increasing of decreasing the net spring rate

                            Obviously the spring rate of a spacer is very high

                            Originally posted by salty_monk
                            More than one spring is just a way of changing spring curve, much like the progressive wind.

                            In some 550 forks I dumped the 4" additional spring & put in a 4" spacer, worked great.

                            In my opinion putting in a valve spring is a waste of time! If you want more preload add more spacer without cutting the spring. Putting in a valve spring would be like putting in less spacer just a complicated way of adding more preload.

                            Dan

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