Interesting Mathews S2 tuning issue…

Home Forums Archery Tech Forum Interesting Mathews S2 tuning issue…

This topic contains 5 replies, has 4 contributors, and was last updated by straightedge123 StraightEdge123 1 year, 3 months ago.

Viewing 6 posts - 1 through 6 (of 6 total)
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  • April 11, 2013 at 11:37 am #573516 Back to Top REPORT
    thedoctorreal
    TheDoctorReal

    Joined: 3/18/2009
    Ok…working on a bow for a friend (though he wants to trade me for my Hoyt..hehe )

    Bow specs:

    Mathews S2, 60-70# limbs (I removed them and confirmed the proper limb deflection during setup)
    26.5″ draw (bow came with a 29″ cam though) with high let-off
    VaporTrail string/cable w/ VTX material and halo end/roller serving
    Bow was new, won at a NWTF banquet, at the time it came into my shop.

    The issue:

    Bow is perfectly in spec…A2A is 33″ exactly, cam timing is spot on, brace is perfect, idler is straight at full draw as tuned with static and dynamic tuning in my draw board, and draw length is just .25″ long for a total of 26.75″.  That said, the bow is only hitting 66# with the limbs totally cranked.  I inspected the limbs and they are cherry…no damage at all (bow was new when it came into my shop).  Pockets are perfect, as is the cam and idler wheel.  I used to be a Mathews tech, so, I checked EVERYTHING out I normally would have when I was a Mathews tech.

    My hypothesis:

    I spoke to a tech at Mathews, who is a friend of mine, and he said the following:

    1)  The string/cable material paired with the end serving (halo) throws off the geometry of the bow a little, resulting in about 2# of draw weight loss.  I have heard of this happening before and had it happen to me once with my S2 a few years back.  Anyone else care to chime in on this?

    2)  The fact that it only has a 26.5″ cam on it does not allow the limbs to fully compress, which results in another 2# loss in draw weight.  I tested this and installed the 29″ cam which came on the bow and I was able to recover about 1-1.5# in draw weight, which I again lost when I installed the 26.5″ cam.

    So, anyway…has anyone else ever had an issue like this with a S2/Switchback in the shorter draw lengths?  I know when I had my S2 many years ago (at a 27″ draw) I could only get 68# out of it, again with the VaporTrail VTX/halo material on my strings/cables.

    Just looking for anyone who has had similar experiences and what solutions you came up with.

    April 11, 2013 at 11:59 am #573525 Back to Top REPORT
    blackdog
    BlackDog

    Age: 63
    Joined: 7/21/2004
    “”1)  The string/cable material paired with the end serving (halo) throws off the geometry of the bow a little, resulting in about 2# of draw weight loss.  I have heard of this happening before and had it happen to me once with my S2 a few years back.  Anyone else care to chime in on this?”"
    ———————————————————————————-
    When I used Vapor Trails on an Outback, I had the same thing happen. Ended up twisting the cable to bring it up to spec. but the cable ended up looking over-twisted to me. Worked well though. Ended up going back to a Barracuda string.

    Question: if the bow is new, why did it have VaporTrail strings?

    My Switchback (04) with Mathews strings @ 27.5″ DL had no problems getting to 72 lbs maxed.

    I read a long time ago (on this forum) that string dia. has something to do with lost weight. Smaller dia. string sits lower in the groove on the idler and cam????? Would explain the GEO factor in my mind.

    April 11, 2013 at 12:10 pm #573527 Back to Top REPORT
    thedoctorreal
    TheDoctorReal

    Joined: 3/18/2009
    The Vaportrail string/cable was installed by me when he brought the bow in.  The customer knew about the shorter-draw cams eating cables and wanted to just put Vaportrails on it right off the bat.  I should also add I am a Vaportrail staff shooter, so, he liked the wares I had shown him (custom colors and all).  So, it didn’t come with the Vaportrails on it…I installed them after I broke the bow down and checked everything out before starting to install string/cable and tuning.

    Do you happen to have a link to that thread speaking about string diameter and lost weight?  I need to refresh my thinking….

    Anyone else?

    • This reply was modified 1 year, 3 months ago by thedoctorreal TheDoctorReal.
    April 11, 2013 at 2:21 pm #573538 Back to Top REPORT
    bow-drawn
    Bow Drawn

    Age: 62
    Joined: 11/14/2007
    View My Bows
    6673_13476_Setting_Your_Single_Cam_Mathews_to_Spec_larger
    I
    f you click on it the picture expands. This might help with your situation. I just put new strings and cables on my switchback made of 452X and I had to add 4 twists to the cables to gain about 5 pounds back to max out at 72#. I also had to adjust the yoke to get the idler to pull straight back.
    April 11, 2013 at 5:16 pm #573567 Back to Top REPORT
    blackdog
    BlackDog

    Age: 63
    Joined: 7/21/2004
    “Do you happen to have a link to that thread speaking about string diameter and lost weight?”

    ———————

    No I don’t have a link and I did a search – came up blank. It was probably back in 2005 or 06. Been a long time. Maybe someone else could help out.

    Sorry I can’t provide a link. {#emotions_dlg.mathews_crying}

    Bet Macolos would know about string dia. Probably giarcher. I’m sure there are others also.

    April 12, 2013 at 7:39 am #573613 Back to Top REPORT
    straightedge123
    StraightEdge123

    Joined: 10/22/2007
    I remember Brian (gjarcher) talking about this once and it agrees with what is in this thread thus far.  I have an S2 and have not replaced the original strings with originals but used custom strings.  I believe the string builder shortened up the string and/or cable slightly each time they were built so that the additional diameter of the serving used would not take away from the poundage that the bow would develop.  Hence, at least for my S2, I have no problem at 29″ maxing the bow out about 2 pounds above the peak weight.   Even with this, my specs are still right and my cam timing is perfect, and I shoot with mine maxed out.
    Mathews S2 / Copper John 4-pin / QAD HD LD / Worlds Best Strings / 808 Bowslings / Easton Bloodlines
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