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  • Chassis design?

    Hopefully Chrisguyw will chime in
    I've tacked this together to try and get some torsional flex and it feels pretty good
    The torsional flex feels good but the center of the chassis also has vertical flex which would act under acceleration. My consern is this will cause wheel hop coming out of the corners. The torsion member is .045 and the connectors are .055 all K&S piano wire. Anyone have any suggestions on how to reduce the vertical flex without stiffing the torsional flex
    PS there is no room up the center under the motor
    Thanks in advance Dave

  • #2
    My advice....build and fix the guide post and run the chassis to see what sort of performance you get...I doubt wheel hop will be a problem if the tires are a tight fit or have been glued and trued and the motor is firmly fixed.

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    • #3
      What tire compound are you using? If it's urethane, then the chassis may be fine as it is. Rubber or silicone may require something stiffer.

      Once you have the guide mounting in place, run a single wire back toward the motor down the center of the frame, ending just in front of the motor. Then solder a cross bar of brass strip that rests on the "torsion" rails but is only soldered to the center spine. That should allow for flex longitudinally, but stiffen the chassis laterally.
      Dennis Samson

      Scratchbuilding is life
      Life is scratchbuilt

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      • #4
        Thanks for the advice guys I think I’m headed in the direction you’ve suggested
        My thinking is if I’m not happy with the results the chassis is still useable by adding another longitudinal member and stiffening it up we will see what happens
        This is another modified being built for Harry’s summer slam so it will be running PG uerathane

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        • #5
          A lightweight chassis like this may need to be tuned with weight. But, since it's gonna be raced on an oval you can bias it to the inside and really help the handling. It may take time to find the sweet spot for the final center of gravity.

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          • chrisguyw
            chrisguyw commented
            Editing a comment
            You can add weight, but, if the torsional and longitudinal flex is not correct, it is largely a waste, as weight will not rectify the basic issue.

        • #6
          Originally posted by 4424ever View Post
          Hopefully Chrisguyw will chime in
          I've tacked this together to try and get some torsional flex and it feels pretty good
          The torsional flex feels good but the center of the chassis also has vertical flex which would act under acceleration. My consern is this will cause wheel hop coming out of the corners. The torsion member is .045 and the connectors are .055 all K&S piano wire. Anyone have any suggestions on how to reduce the vertical flex without stiffing the torsional flex
          PS there is no room up the center under the motor
          Thanks in advance Dave
          Hi Dave.........good job so far ., and by the looks of things, you may be OK ..........add your front crossmember/guide tongue and give it a run before changing anything.............if you do get axle tramping (chassis too soft longitudinally) there are a few relatively easy fixes......let us know the outcome, and we can go from there.

          Cheers
          Chris Walker

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          • #7
            Thanks for the replies I’m happy to report after some minor tire sanding to get an idea how it will work it seems to be just fine although loose without any body weight on it yet. Onwards and upwards as they say

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            • #8
              Hi Dave, Good to hear that it seems to be working .............if you do get axle tramping,.....make a "U" shaped bracket (.047 wire will be just fine), that fits between your main chassis rails, and crosses in front of your endbell, 1/4" long (or so) legs will be good . Solder it in (legs facing the rear axle) with the cross piece just touching the endbell. Use a drop of shoe goo (etc.) to glue the crossbrace to the endbell..............this should help a lot, and, I would advise this regardless.

              As well, looks like you need to scrub your chassis a little quicker after using acid flux

              God job !!,....and keep us posted.

              Stay Safe

              Chris Walker

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              • #9
                too much smoke in my eyes and I’m lazy besides paint can cover a lot
                kind of like making a silk purse out of a sows ear

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