Home Forums Tech Talk Plastic bumper add-on: how-to guide.

This topic contains 2 replies, has 2 voices, and was last updated by  Ted Hamilton 2 years, 9 months ago.

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  • #43222

    Ted Hamilton
    Participant

    So….

    Like many, I found myself with an older chassis that had the frame-rail width bumper, chrome-style.  With the advent of the new bodywork, there was no easy way to add the plastic rear bumper.  However, my local track REQUIRES the aforementioned abomination, so….

    Step 1:  measured diameter of rear bumper — 25mm (~1″)

    Step 2: Source a stock car “weight clamp”.  Mine was from AllStar Performance, If I recall correctly.  It has a 1/2″ tapped hole on either side of hollow 1″ split clamp.  See pic below:

    If you look closely at this Swiss Hutless chassis, there is no provision for the standard rear bumper mounts that fit into the frame rails as these frame rails curve around to support the “torsion bar”….

    So, after sourcing the clamps, I removed the Ridolfi hardware from the bumper, and made two “c” channel aluminum plates, as seen below:

    If you look, the 1/2″ bolt showing above goes into the tapped hole in the clamp, and the “c” faces forward, leaving a flat face for the bumper to bolt to.  In this shot, the holes for mounting the bumper haven’t been drilled yet.  They will go on the “outside” of the braces.  The plate started as flat diamond-plate, but was measured to be 2.25″ tall with a 1/4″ bend on top and bottom to stiffen the assembly. Looks like this: [

    Step 3: Drill holes in plates as necessary to….

    Step 4: Mount bumper to “old bumper” using the clamps and new plates:

    Is it CIK/FIA approved?  No.  Will my local tech inspector allow it?  I hope so…  The bumper is far weaker than the hardware attaching it…  But this system does have the advantage of easy removal if I want it off for test days, and it does mount the bumper far enough back from the pipe that it might escape heat damage.  There’s about a 3″ gap between the bumper and the rear tires — I think that’s about where it normally falls, so I’m crossing my fingers and heading to tech soon.  I’ll update the thread.  Hope this helps someone.  Here’s a link to the clamps I used (also available in other dia’s…)

    http://www.amazon.com/gp/product/B006K8YVLU/ref=pd_lpo_sbs_dp_ss_1?pf_rd_p=1944687722&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B006K8YX3G&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=139GVBRG01K8V1BKZSB0

    www.facebook.com/hamiltonhelmets/
    2014 Praga Dragon / IAME KA-100

    #43255

    Walt Gifford
    Participant

    Looks OK to me.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    #43286

    Ted Hamilton
    Participant

    I’m pretty sure it will be fine for the “club racing” I’m doing…  🙂

    www.facebook.com/hamiltonhelmets/
    2014 Praga Dragon / IAME KA-100

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