What do you guys think of 3/4 cm heims

Discussion in 'Axles / Suspension / Tires' started by jeepzilla, Dec 20, 2010.

  1. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    I am building a budget buggy. Do not know the weight, but two people can pick the tube frame off the jack stands.
    Specs:
    sbc 350
    sm465/np205
    dana 60 front with detroit
    14 bolt rear with detroit
    4:56
    full hydro steering
    some form of air shocks 2 inch 16 or 18 not sure yet
    40 inch tire
    weld on beadlocks
    glo diff covers
    4 linked front and rear
    Question: I am using 3/4 CM heims with mis-alignment spacers and 5/8 bolts.
    Used 1-1/4 JJ on last buggy w 9/16 bolt.
    Weak point there was the 9/16 bolt.
    With the 3/4 heims and the 5/8 bolt the math seems to work.
    Not going to race and can feather the throttle.
    What do you guys think about the heims?
     
  2. snappy

    snappy YHDG's adopted son!!! Moderator

    Joined:
    Jun 19, 2007
    Location:
    high point
    They will start to rattle after just a few trail rides. The rebuildable joints can be tightened up to stop this.
    Edit this also seems like it will be a heavy rig to use use 3/4 stuff too.
     
  3. TPS

    TPS Active Member

    Joined:
    Sep 13, 2007
    Location:
    leicester
    high quality kevlar/teflon race cm joint will last years.
    fk p/n hrsmx10t.
     
  4. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    That is what I am using. Here is some addtional info.
    sbc350 550 pds.
    sm465/np205 360pds.
    dana60 518pds.
    14bolt 450pds.
    tires 404pds. without steelie wheel and weld on beadlocks
    tubing est. @ 600pds.
    _______________________

    2882 pds. will finish out less than 4000pds.

    Stock cj5 weighs this.


    Bolt Tensile Strength (Breaking Strength - pounds)

    Grade 5 Grade 8
    Coarse Fine Coarse Fine

    9/16 21800 24400 27300 30400
    5/8 27100 30700 33900 38400

    3/4 x 3/4 Heims Rated over 14 tons
     
  5. jds97Wrangler

    jds97Wrangler Active Member

    Joined:
    Oct 19, 2008
    Location:
    Mccleansville, NC
    Appears you have made up your mind to use the 3/4 heim joints and and your just looking for someone to confirm you decision.
     
  6. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    Not yet, have not set axles under rig. Have not welded my first link tab. I do have all my tabs from MudPro w/5/8 holes though. I have all the .25 wall 1inch ID tubing here in the shop.
     
  7. drkelly

    drkelly Dipstick who put two vehicles on jack stands

    Joined:
    Mar 21, 2005
    Location:
    Oak Ridge/Stokesdale, NC
    That is what I have heard and seen too. Seems like most people who choose to use rod ends are going with 1.25" size nowadays. Sometimes smaller ones on the upper links.
     
  8. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    In reality, should you not take into consideration the tensile strength of the heims that you are running on both ends of your link. Seems to me that decreases stress and increases the actual tensile strength. Please correct me if I am wrong.
     
  9. paradisePWoffrd

    paradisePWoffrd Recovering Project Junkie

    Joined:
    Nov 5, 2005
    Location:
    Newton, NC
    the problem isnt the tensile strength of the heims, it's the shear strength of the shank and bolts, on your lowers... you should be fine with a 5/8" bolt in double shear, but you will break the body or shank when you drop it on a rock...
     
  10. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    The force of the links dropping off on a rock will shear the heim. That is what will be hitting or dragging across. What is the shear strength roughly 60% of tensile strength.
    That is still over 8 tons of shear strength on a 2 ton buggy. If I return the the heims and get 1-1/4 and new dom, that adds another grand to the budget buggy. Heck I don't know what to do. Thanks for all the input.
     
  11. snappy

    snappy YHDG's adopted son!!! Moderator

    Joined:
    Jun 19, 2007
    Location:
    high point
    I have broken 2 3/4" shank heims on my last buggy, sheared the shank, it weighed 4200lbs with toy axles at the time. I went with ballastic fab joints this time with 2" .250 dom for my lowers and 1 3/4" x.120 for my uppers. We are not bashing your set up at all but alot have been there done that. Stan is the man at Branik but from the sounds of what you are wanting to build, it will be ALOT heavier than what they typically build. IMO return the heims u have for lowers, keep the uppers, and order 5/8" shank joints or 7/8" or 1" shank heims.... thats my .02. If you think it adds alot now think about having to buy them twice and replace what breaks when one fails(ie bent shock etc etc).
     
  12. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    Your right. Breakage can cost more than the addtional cost of the bigger heims. Thanks!
     
  13. paradisePWoffrd

    paradisePWoffrd Recovering Project Junkie

    Joined:
    Nov 5, 2005
    Location:
    Newton, NC
    you will be pushing it to get under 4k with those parts...

    You are right, it might be hard to put 16k of force on the lower link to shear the heim, but if you land on a pointed rock, it is easy to put that much force as a point-load on a heim joint... you haveto calculate the force of the vehicle landing on a rock at any given rate, and that will be alot higher than 4k... Also you haveto think about fatigue over time and how that joint will just get weaker everytime it bashes or drags on a rock until it finally breaks...

    You should be fine with 3/4s in the uppers and they are only in tension and compression on a proper link system.

    I would trade the 3/4 & lower material/bungs for cartridge joints with 5/8 hole and 1" or 1.25" shank
     
  14. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    The jury has decided. 3/4 going back 1-1/4 coming for upper and lower. Thanks guys!
     
  15. hadfield4wd

    hadfield4wd Active Member

    Joined:
    May 21, 2010
    Location:
    Roanoke, VA
    I know that the rig that Dustin Webster ran in KOH 2 years in a row had Ruff Stuff 7/8 x 3/4 heims.
     
  16. CTRaceWorx

    CTRaceWorx Well-Known Member

    Joined:
    Aug 23, 2007
    Location:
    Charlotte
    I could possibly see running 3/4 heims on the uppers of a light rig but never on the lowers regardless of the weight. With your setup I wouldn't run anything less than a 1 1/4 heim/joint.
     
  17. jeepzilla

    jeepzilla Member

    Joined:
    Dec 25, 2008
    Location:
    Draco
    1 1/4 heim/joints on all 16 ends and then just hammer it. Thanks everyone and Merry Christmas!
     

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