I'ma Leaf Spring guy...until now

Discussion in 'General Tech' started by R Q, Jul 20, 2019.

  1. R Q

    R Q Well-Known Member

    Joined:
    Apr 4, 2005
    Location:
    Charlotte
    [​IMG]
    This is my Leaf sprung Jeepster. I've run Alcan leaf springs forever and they've done me well...for leafs. I want to link and stretch the rear about 10". Jeepsters are 101" WB and mine is about 102" due to my spring pads/plates.
    LOL I need ten inches! :D
    I've read a lot of calculators and articles but it is a bit alien to me because I think and see in 3D. Pictures on the internet don't do much for me.
    My frame is 29" OD at the rear and the best Jeepsters I've seen run a 3 link rear to save space.
    My rig has a SF Dana 60, 35 spline with custom Moser axles from an International Travelall in the name of keeping it 5 lug front and rear...Old school cool was the thought...:shaking:
    I tend to learn from my mistakes, I'm trying not to do that this time. The Jeepster guy I have asked for his "recipe" is not following through.
    Needed info: Jeepsters LEAN! The front with leafs flex like Hell! Rig weighs about 5K as is. Running 37" Interco combo, Swampers rear/ SX front. I have a 3'' Ill-advised body lift(from 2002) that I'm going to lose 2" of hopefully this Winter but my cage and steering is built around it so maybe easier said than done.
    Show me some sites or info that show the 3-4 link info that I'm looking for if you got them.
     
  2. a_kelley

    a_kelley mechanical fixer

    Joined:
    Jan 26, 2010
    Location:
    Rutherfordton
    @Van-go had links to the link calculators.. put in dimensions, locations, weights & fine tune it. It's not for the faint of mechanical. Small adjustments make big differences. But basically you want your links flat/long as possible. More info about your driveshafts setup is needed to point you in right direction. Cv joints require pinion pointed at output, whereas slip yoke needs to stay level throughout travel. Link length determines what happens so far as pinion angle & spacing determines roll center & more. Setting up a 3/4 link, play with the calculator and find the happiest medium between all factors you must consider.
     
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  3. NickMaul

    NickMaul Well-Known Member

    Joined:
    Jul 4, 2009
    Location:
    Norfolk, VA
    Barnes4wd has a small write up about 3 link 4 link stuff that can get you started. Not sure a 3 link is the best choice for the rear. That’s a lot of force on one upper link. I think if there is room for a 3 link you’ll have room for a triangulated 4 link in the rear.

    Pirate4x4, even at its worst, had some great buried 3/4 link tips. I hope you enjoy lots of thread reads!


    Sent from my iPhone using Tapatalk
     
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  4. Stuntman Autoworks

    Stuntman Autoworks Instigator of things

    Joined:
    May 6, 2010
    Location:
    Sanford NC 27330
    You deffinately want a dual triangulated rear. Front is debatable on 3 vs 4 link but personally I don't like 3 links. Theres alot of force on that one upper link and if it fails everything attached to the axle is going to go out with it. I prefer a 4 link but there are plenty that run a 3 just fine.
     
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  5. paradisePWoffrd

    paradisePWoffrd Recovering Project Junkie

    Joined:
    Nov 5, 2005
    Location:
    Newton, NC
    Driver @uglyjeepoffroad has a 4 link in the rear of his commando, that works well. Maybe he can share some of the dimensions.
     
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  6. R Q

    R Q Well-Known Member

    Joined:
    Apr 4, 2005
    Location:
    Charlotte
    Have you seen his junk? :D J/K Chris! I do plan to reach out to him to check his build. I've wheeled with him many times but never inspected it closely.
     
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  7. Mac5005

    Mac5005 Welding Instructor

    Joined:
    Oct 19, 2005
    Location:
    Rocky Mount
    Read through this a couple times. Suspension Theory
    Suspension Theory

    I never finished my complete thoughts but should be enough to get started. The rest we can help with fine tuning the setups once you have it close in the calculator.

    Rule of thumb to start:

    Lower links same length as tire dia.
    Upper links 68-72% of lower length.

    Vertical separation of lower/upper links at axle, 25% of tire size. 70% of this number at frame mounts.

    Antisquat 70% with no more than 10% increase in droop.

    6 degrees or less of pinion angle change.

    Roll axis angle as flat as possible.

    Roll center height as close to cog as possible.

    Front roll center higher than rear, but not by much.

    Obviously in the front, it may be higher priority to have caster more consistent thru travel to keep the steering happy, which sacrifice some AS/AD deviation, which is ok.

    Front AS/AD 40%.

    Obviously if single u joints at tcase, you want the pinions to move towards more parallel, while double cardans like to have the pinion pointed at the output.

    If not using a panhard then need at least 40* triangulation between all the links.

    Yes the upper of 3 link sees more load than of 4 link, but also doesn’t have to locate axle laterally. That’s the job of the panhard. Make the upper 3rd link identical to lowers.

    4 link, the upper links can be smaller than lowers bc of no impact chance with rocks.

    A double triangulated rear is hard to beat, and a 3 link front is great when retaining a mechanical drag link.

    If ditching the drag link for full hydro, then double tri the front as well.


    If you can’t double triag a 4 link, then next option is single tri, or 4 parallel (from above) links with a panhard.
     
  8. mcutler

    mcutler Well-Known Member

    Joined:
    Apr 17, 2010
    Location:
    mt.airy nc
    Just food for thought;

    I've never ran links that were the same length as my tires; (aside from the trailing arms on the comanche.)

    Copper crawler; dual tri front and rear, 118" wb, 18" belly on 43's, 8" up and down, 16" fox c/o.
    - ALL links were 36" bolt to bolt
    - lowers angled up toward the axle, front and rear;... wheel recession = better ride characteristics.
    - did not run a calculator on it until long after it was built...


    This buggy worked VERY well.

    Comanche: dusk tri f/r, 115" wb, 16.5" belly on 39's, 8 up/ down front, 10 up/ down rear with trailing arms

    - front links are literally the steel links from the copper crawler that I carried for spares after going aluminum... again 36" bolt to bolt, top and bottom...
    - trailing arms are 39", uppers are 41" iirc
    - same as above, links angle up towards the axles from belly.
    - drew the suspension on graph paper, through travel, with pinion change, before I put it in the new V4 calculator that does front and rear simultaneous. I knew what I wanted without knowing/caring what the computer says I had.

    With all that said... get the lowers parallel as possible to the ground. Longer uppers, can help with maintaining the pinion to point towards the tcase.

    Don't be afraid of a lower belly! If it's touching rocks... you know where you are...

    Anything you build in way of links; (provided the guidelines that Scotty posted are always kept in mind, with consideration they are not hard and fast...) is going to be SO much better than leaves... you wouldn't know the difference, frankly, between a good or bad setup.

    Have fun, good luck, and it's ok to screw it up a little, and make it right on the second attempt! Get it cycling in the shop, and you'll see what's working and isn't... calculator or not.

    Sent from my SM-G892A using Tapatalk
     
  9. Croatan_Kid

    Croatan_Kid How's your hammer hangin'?

    Joined:
    Nov 4, 2007
    Location:
    New Bern
    You can always just take it to Cutler with a blank check. It'll be pretty awesome when you get it back :D
     
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  10. mcutler

    mcutler Well-Known Member

    Joined:
    Apr 17, 2010
    Location:
    mt.airy nc
    Cash only establishment

    ... and a long wait

    Sent from my SM-G892A using Tapatalk
     
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  11. Croatan_Kid

    Croatan_Kid How's your hammer hangin'?

    Joined:
    Nov 4, 2007
    Location:
    New Bern
    *breifcase of large denomination bills

    My bad :D
     
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  12. 87TPIYJ

    87TPIYJ Active Member

    Joined:
    May 12, 2016
    Location:
    Jacksonville FL
    Bust out the tape measure and start pulling some measurements. What's posted above is a good start. Your limiting factors will be packaging with the full bodied rig. Don't get too hung up on it. Just try to get the AS if you can in the 80ish range (mine is adjustable from 65-85) and roll axis angle as close to zero as possible. Here is a link to the triaged 3 and 4 link calculators. I used V3.0. Im finishing up my 4 link front and rear build now.
    Triaged 4 link calculator ?? - Pirate4x4.Com : 4x4 and Off-Road Forum
     
    Last edited: Jul 25, 2019
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  13. R Q

    R Q Well-Known Member

    Joined:
    Apr 4, 2005
    Location:
    Charlotte
    Even though I am "watching" this thread, just getting back up top for now. Got measurements and working with them. I think I'm going to have to remove my fuel tank and get a fuel cell to get enough stretch to make it worth my while.
     
  14. R Q

    R Q Well-Known Member

    Joined:
    Apr 4, 2005
    Location:
    Charlotte
    These videos are great at explaining what I miss in the printed descriptions and pictures.


     

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