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Technical Rotational joint

Discussion in 'The Hokey Ass Message Board' started by Hackerbilt, Feb 8, 2015.

  1. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Guys...
    If for some reason you wanted to cut a 2" seamless tube axle in two and allow both halfs to rotate using a center joint, what would be a good joint to use?
    I'm talking only about 1 inch +/- of total rotation from one extreme to the other.
    I'm more interested in something from a donor than something custom built at a machine shop etc.
    It would have to be strong and durable...and not ugly.
    The joint would have to be of tight enough tolerance to prevent sagging or looseness that could result in noise and chatter.

    BTW...to be clear...I'm NOT talking about setting up an axle as a swing axle. Thats easy, but not what I want.
    I'm talking rotation like you find in a steering column for lack of a better description.
     
  2. gnichols
    Joined: Mar 6, 2008
    Posts: 11,042

    gnichols
    Member
    from Tampa, FL

  3. squirrel
    Joined: Sep 23, 2004
    Posts: 50,199

    squirrel
    Member

    From your description, I have no idea what you want. Do you want a universal joint? A spline? A hinge?

    Also, how does one measure one inch of rotation? I could understand a number of degrees or rotation, or some fraction of one revolution, but measuring rotation with a unit of length is kind of confusing to me.

    Maybe the problem is you didn't tell us what you're thinking of doing with this, so it's kind of hard to visualize it.
     
    volvobrynk and pitman like this.
  4. pitman
    Joined: May 14, 2006
    Posts: 5,151

    pitman

    C'mon Hack, fess up. What cha got going there?
     
    volvobrynk likes this.

  5. blowby
    Joined: Dec 27, 2012
    Posts: 8,040

    blowby
    Member
    from Nicasio Ca

    I'm thinking brass bushings pressed into the axle and a solid shaft inside.
     
  6. Rootie Kazoootie
    Joined: Nov 27, 2006
    Posts: 8,134

    Rootie Kazoootie
    Member
    from Colorado

    Something like this? Inner shaft riding in bushings/bearings-radial thrust bearing between the axle tubes and a connector rod to keep it together. Think of how a VW torsion beam is constructed and it will become clear.
     

    Attached Files:

  7. nrgwizard
    Joined: Aug 18, 2006
    Posts: 1,456

    nrgwizard
    Member
    from Minn. uSA

    Try again...

    Hackerbilt:
    Are you wanting each half of the front axle to be able to independently rotate in an arc correctly using hairpins instead of the 4-bar deal?

    If so; a guy by the name of Walt Leatherman did that on his x-Kent Fuller-built VolksRodT, & posted a how-to on Volksrods.com. Don't have the link handy.

    Short version, (iirc); Walt used 2 thick-walled tubes, w/2 bushings (oil-ite?), a couple of washers, & a long bolt to do the rotational-device. Held it (& the thick-walled axle halves) in place w/2 rows of 4, on each side, tapered-head allen sockets. Almost invisible the way he did it, & worked well. Machining required. You might be able to find some suitable pieces at Grainger, but just a bolt-together deal, I'm guessing not.

    HTH.

    Marcus...
     
    Last edited: Feb 8, 2015
  8. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Yeah...you guys pretty much nailed it.
    I want to run fabricated split bones(!) with a tube axle.
    Basicly I'm going spring over to shorten my long wheelbase a bit and tighten up the look of my frontend.

    By doing so my Hairpins would need shortening and the front end already had very little articulation to start with. Plus, due to the original builder mounting the hairpin heim joints directly thru the frame the hairpins are on an angle I don't like. I don't really like the thought of those spindley little ungussetted hairpins absorbing all that braking torque combined with the big block weight either.
    Bottom line...I want to run much longer, level, split bones to drop brackets farther back on the rail.
    I'm debating if a rotational joint would be a worthwhile addition, and even if its possible.
    I HAVE to keep some articulation up front as there is basicly none out back...and split bones aren't particularly noted for allowing flex.
    This thing was built for Drag racing and has a very strong parallel ladder bar setup with well braced bars out back and no flexibility at all.
     
  9. squirrel
    Joined: Sep 23, 2004
    Posts: 50,199

    squirrel
    Member

    So, you want to avoid buying an I beam axle? And cut the tube axle in half, and allow it to rotate, while still keeping it's strength and rigidity.
     
  10. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Yes! :D

    Yeah...I know...
    Actually things have just snowballed a bit from where I was planning when I started.
    Nothing is cut yet and I can always keep the hairpins and use drop brackets with those...but that does nothing to address the issues with the spindley hairpins and the already limited flex I'm dealing with.
    No harm in asking questions and apparently it has been done successfully before...

    I have several I beams...undropped...but using one brings up a whole other list of issues and expense.
     
  11. Rootie Kazoootie
    Joined: Nov 27, 2006
    Posts: 8,134

    Rootie Kazoootie
    Member
    from Colorado

    Back in the day Frank Kurtis and Jim Culbert (CAE) eliminated the inherent bind of a tube axle by attaching the hairpins on one side to the axle on a rotating collar.
     

    Attached Files:

  12. pitman
    Joined: May 14, 2006
    Posts: 5,151

    pitman

    ^^^Looks as though this setup would need to handle all the braking force/torque thru one side. Hmmm. :eek:
     
  13. BillWallace
    Joined: May 6, 2011
    Posts: 132

    BillWallace
    Member

    Yes that is correct one side took the brake force but on a track car especially on dirt tracks one wheel on the front axle takes most of the braking anyhow/
     
  14. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,608

    Rusty O'Toole
    Member

    How about introducing a small amount of resiliency by putting rubber or urethane bushings in the hairpins?
     
  15. gnichols
    Joined: Mar 6, 2008
    Posts: 11,042

    gnichols
    Member
    from Tampa, FL

    Again, the DSE swivel joint may be just what you need. Give them a shout tomorrow. Their links are designed with built-in rotation along the axis (all hidden inside) the bar (tube) itself. Splicing one into the center of your axle would probably work. The Kurtis trick with a birdcage on one side is also a VERY good idea. Gary
     
  16. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Yeah...no interest in using a collar on one side. The potential for pulling under braking is too great.
    Using bushings in the hairpins has potential...but the axle is set up for Clevis ends so things would likely be difficult.
    Besides...I'd prefer to use split wishbones IF possible. Thats the reason this thread was started! :D
     
  17. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    The DSE joint is right along what I had in mind but I think its a bit small. A bigger version might do the trick as you say.
     

  18. Yes, Walt does some nice stuff.
     
  19. nrgwizard
    Joined: Aug 18, 2006
    Posts: 1,456

    nrgwizard
    Member
    from Minn. uSA

    Hackerbilt;
    Any joint articulation w/hairpins using clevices is done thru the heim joint at the end (or tie rod end if your doing old-style). Bones would be the same way. Both have "solid" mounting @ the axle, & both flex to various degrees under load. Don't see a problem here. The rotational joint does away w/a lot of the twisting stress on a tube axle. Not all of it, but a lot. Using tierod ends as the pivotal point works well. Doesn't look as trick as heims, but probably works better through the range of angles.

    Unkl Ian;
    & that's why I mentioned Walt.

    Marcus...
     
  20. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,728

    Atwater Mike
    ALLIANCE MEMBER

    ...and the 'Golden Eagle' syndrome followed, then... Next year was morphed into 2 bars on left, and one on right: the "3-bar" iirc.
    Am I close, Rootie? (LOVE those Kurtis designs...(I had a '56 CAE flathead sprint car with a 3-bar...)
     
  21. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    I just signed up at Volksrods to check out Mr Leathermans axle but I can seem to find any info.
    Wouldn't have a link would you???
     
  22. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Thank you Ian!
    Now thats interesting!
    I really like what he has done and its really simple.
    What strikes me the most though is the picture with the axle lifted very high on one side.
    The two axle halfs have only misaligned a small amount compared to the angle achieved.
    I expected it to be much more at that angle to tell the truth!
     
  23. gnichols
    Joined: Mar 6, 2008
    Posts: 11,042

    gnichols
    Member
    from Tampa, FL

  24. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,251

    Hackerbilt
    Member

    Yes, I agree 100%! Amazing work there for sure.

    I on the other hand have decided to go the keep it simple route and now have the new brackets almost made and drilled to keep the hairpins. Rotational joints be damned! LoL
    Instead of shortening the hairpins I will make new drop brackets to hold them at an angle I like, farther back on the frame.
    I'm convinced now that with the long hairpins and the limited suspension travel my car has, I really have no need to go that radical.
    If I had stuck with the split bone idea it might be a different story.
    Thanks guys!!!
     

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