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4 link springs and joints

Discussion in 'The Garage' started by 1977k5, Jan 10, 2007.

  1. 1977k5

    1977k5 3/4 ton status Vendor

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    What should I run? It seems my 3 options are coils, airshocks, and coilovers. It also seems that they increase in performance and cost in the order I listed them. Can airshocks even support the weight of my rig (~5200 lbs, but the rear will be lighter than the front I'm sure)? Will I be happy with regular coils and shocks? I am willing to spend money on doing it right the first time but money is a concern (isn't it always :doah:)

    Second, what size joints/bolt should I be looking at? Any suggestions on which joints to use? There are a lot of options. What about high misalignment spacers? Do I need that much joint movement and is it worth the smaller bolt size?

    Finally, what about tubing sizes for the links? I was thinking about using 2" .120 wall for the uppers and 2" .375 wall for the lowers. Both put me above a factor of safety of 1 values on the calculator, but I don't really want to bend the lowers. The FS for the lowers bending is 1.34, is that enough? Should I use chromoly tubing on the lowers or maybe throw a gusset on the top of it to resist bending?

    Thanks in advance guys :thumb:
     
  2. JpEater

    JpEater 1/2 ton status

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    Go coilovers. You would regret it if you didn't. I don't think air shocks would support that weight. I would go 2'' .375 on the upper links and lower links as well and I think chromo would be overkill for your blazer.
     
  3. 1977k5

    1977k5 3/4 ton status Vendor

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    Why .375" thick on the uppers? The only reason I am going that big on the lowers is to keep them from bending when they get bashed on rocks. The uppers should only see compression/tension so 2" .120 wall should be more than enough (the 4 link calculator agrees). Thanks for your input
     
  4. muddybuddy

    muddybuddy 3/4 ton status

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    im going to run coils when i do my setup for now so i can get it all together for cheap, compared to coilovers. eventually i may go coilovers when the fund allow down the road
     
  5. Greg72

    Greg72 "Might As Well..." Staff Member Super Moderator

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    If you only have a 1.34 FS in bending on those lowers, you might want to use a thicker material, a larger diameter material, or a shorter link..... the shorter link helps your Bending FS a lot if your design allows it.

    As for mis-alignment spacers, I'd evaluate that once you've got things mocked-up. It should be obvious that you build the suspension with NO misalignment in the heims at static ride height (why limit the usable angularity by not setting up your mounts correctly?). Then as you articulate the suspension you should be able to take measurements of the angles at the heims and assess whether you are close to their operating limits or not...
     
  6. ntsqd

    ntsqd 1/2 ton status

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    Air is not a great spring. It's "spring rate" varies too much with temperature. In a light weight little buggy the rates are low enough to start with that the change probably isn't noticable. With a heavy machine I think you'd notice since it will work the shocks harder and cause the air temp to rise more. I'd cross air shocks off your list.

    I was in agreement with Greg re: centering the SRE's in their movement range at ride height. Then I thot you may want to mock this up first and flex it. Could be that you may need to bias where they are @ ride height to get full use of their angularity.

    Diameter plays a bigger role in bending strength than does wall thickness. With two tubes of the same weight the one with a larger OD will have greater bending strength. I built an Excel file specifically to find out this sort of thing.
     
  7. 1977k5

    1977k5 3/4 ton status Vendor

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    Any advise on which joints to use and what size bolt hole I should be running? They all have force ratings but I have no idea what I will be subjecting them to. What are you guys running? TIA
     
  8. ntsqd

    ntsqd 1/2 ton status

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    Have a look at the "Material Selection" tab of the ExcelCAD file. The numbers in bold are the Factors of Safety. Be sure to enter your rig's weight as precisely as you know it, and note that you need to enter what the rod end's rated strength is "1" means that the strength of the part and the load on the part are exactly equal. Less than 1 means the part already broke. :doah: An F.S. of 2 is a reasonable target to shoot for as that means the part is twice as strong as the theoretical max load on that part.
     
  9. iwaxmyjimmy

    iwaxmyjimmy College web wheeler Premium Member

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    what about a 1/4 elliptic rear?
     
  10. marv_springer

    marv_springer 1/2 ton status

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    Cheap options: Coil, 1/4 el.

    More $$: Air springs

    Even more $$: Coilovers

    I like 1/4 el. springs, and still plan to use them in a future rig. Many people seem to have written them off as "bootie fab" but I think they are a compact affordable way to spring a buggy.
    [​IMG]
    Biggest consideration is to make your springs from a common/available donor rig because you will be installing new springs every couple of years.

    Joints: install the biggest and best you can afford. I like rod end (heims), but some people like the poly flex joints better. I've run 3/4" heims on my 454 buggy w/ success - but it weighed slightly over 3k lbs. For a bigger rig like yours, I'd go at least 1".

    Build your lowers as big as you can stand them. You will bend them. Build extras too. Uppers have a pretty easy life.

    Marv
     

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