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Honda VFR800 (6th Gen) Lowering- rear suspension analysis

Discussion in 'Technical and Troubleshooting Torque' started by oldcorollas, Aug 31, 2016.

  1. #1 oldcorollas, Aug 31, 2016
    Last edited: Aug 31, 2016
    so I did some modelling of VFR800 rear suspension for a customer, to see what happens to the shock compression curve with a couple of different common mods used for lowering.
    1- standard geometry
    2- rotating the triangle around (2 sides are 65mm, 1 is 60mm)
    3- using an 11mm longer dogbone (126mm instead of 115)

    The question was, what happens to shock compression curve, and does anything funky happen (go from linear to S-shaped curve, much harder, much softer etc)

    this is what the triangle arrangement looks like. swingarm pulls up on triangle, dogbone swings upwards and pivots the triangle, triangle pushes shock upwards, simples...

    slight differences in resulting shock compression curves. total standard wheel travel is 120mm

    standard geometry,nothing exciting. rear wheel : shock movement ratio is about 2.75:1
    rear wheel is at right at end of swingarm, shock goes up and to left at 10deg.
    intercepts between arcs used to find location of the bolts on the triangle, blah blah..

    with the triangle rotated so the 60mm length is between dogbone and shock (usually between the dogbone and swingarm), lowers by 25.7mm but shock compression curve is almost identical to stock, maybe 0.5% softer.

    With the (previously available) 126mm dogbone (up from 115mm standard), lowers by 35.2mm, but changes the shock compression curve to be a bit less linear (may be some inflections there, but not a huge deal), and firms up spring rate by about 2.5-3.5% (varies throughout the curve)

    so while "flipping the triangle" sounds a little dodgy, it actually has little effect on rear suspension dynamics and should work a treat.
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  2. Thays ar sum rayal preddy rainbows.
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