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Rear 4 Link

Discussion in 'Center Of Gravity' started by willyswanter, Nov 3, 2003.

  1. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    Well, just noticed the new forum, might as well post right?

    I'm waiting on 4 more parts to come this week and I'm going to start on my rear 4 link and tube back half of the truck.

    Here are my final plans as of now for the 4 link:

    [​IMG]

    I origionally had it setup with around 60% AS but was told that with my wheelbase I would want it around 90-95%. Any thoughts on this?

    I'm going to run 2.5x18" Sways with the tripple rate kit and Eibach coils. Link ends will be Currie 2.5" threaded Johnny Joints on the frame end and 2.5" regular JJ's on the axle end. I actually have the Johhny Joints, 1-1/4" Heims, and RE Joints. I'm still trying to decide on what I want to use. The JJ's and RE joints look almost identical except for the bushing material so I think I'll stick with the JJ's but not sure if I want to run a heim on one end. It's a daily driver still so I'm affraid of the heims being noisy and wearing quickly on the street thus my reasoning behind JJ's on each end. If I do run heims they would be on the axle end with the threaded JJ's on the frame end so it would still be isolated somewhat. But basically I do not see a need for the heims since the Johnny Joints have as much movement as the heims, basically just worried about overall strength on a 8500 pound rig.

    Bed will be gone and it will be full tube back half ending at the back of the tires with a 4 foot wide basket type area in the center for hauling junk, may run bed side skins on it for the street since this is Kalifornia and any tire uncovered is basically as bad as commiting murder around here...
     
  2. Greg72

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

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    Jason,

    It's probably not news to you, but the lower links (pictured in green) can determine a wide variety of anti-squat values depending on the attachment point on the frame end.

    If you're smart (and I believe you are) the upper mount should probably be a series of holes on a mounting plate. Maybe have the existing layout (your 60% antisquat) represent the bottommost hole in the bracket, then add at least 2 or 3 more to increase the angle of that lower mount.

    I was pretty pleased at HOW much change I could get in those values by making both the axle end, and frame end adjustable (maybe 3 or 4 holes options each).... depending on your particular design, maybe you could achieve 60% - 100% just by messing with the upper mount.....


    /forums/images/graemlins/thinking.gif




    ps. I love this forum already! /forums/images/graemlins/thumb.gif
     
  3. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    Yep, I'm going to be making multiple mounting holes in all 4 frame brackets, why not, the mill does all the work of cutting them /forums/images/graemlins/rotfl.gif

    I may make the lower link mounts on the axle adjustable but I'll see how it turns out. Maybe I'll make a bolt on mount that can rotate around the tube to different spots for testing...

    Yes, when I saw this forum I got very excited /forums/images/graemlins/thumb.gif
     
  4. marv_springer

    marv_springer 1/2 ton status

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    [ QUOTE ]
    [​IMG]

    [/ QUOTE ]

    From this image, it looks as if your lower links are going to be above the rear axle. Is this right..?

    I've seen setups like that, and I'm not really a fan of doing that. I'm sure you know that it increases the load in the lower links. For such a big truck, I'd have reservations about doing that.

    I happen to like the higher anti-squat, but it doesn't seem to be popular w/ a lot of builders. We'll see as time goes on if I continue to like it... I'd think w/ such a long wheelbase, your truck would be less sensitive to variation in the squat value...

    Marv
     
  5. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Anti squat guesses are like, well you know, everybody has one. I'm not sure why a higher percentage would be better than lower in a long wheelbase. If anything, I would think that you would want a more neutral suspension (less AS) with the longer wheelbase since you're not going to have as much weight back there and won't have as much weight transfer from the front on acceleration. I'm not totally sure you can go wrong with anything between 50 and 100%.

    I'm going to say the best way to do this would be to run some adjustment like Greg mentioned. We did this on the frame ends on brandon's "mini wally" and I'm really looking forward to playing with it. Although it's set up really neutral now and seems to work pretty well, we might be able to come up with some kind of advantage by playing with it.

    The other thing I would look at is flattening the roll axis a little, I think you're going to want it pretty much level. The truck's going to be light in the rear anyway so you don't have to worry about being able to kick the rear out with roll steer and although technically, no roll steer is only the right thing to have 1/3rd of the time, it's more intuitive and easier to drive if the rear's not trying to pass you.
    You have quite a bit of room to play with it, so you might look at that aspect.

    And just to go ahead and pimp some stuff here (although it really could make your life easier) we do have the brackets that we used on brandon's buggy rear axle as a "kit". They're set up to run the upper links straight ahead and put the lowers above the tube (as you probably remember). It's a re-design for you but they do work well.
     
  6. Sandman

    Sandman 3/4 ton status Author

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    [ QUOTE ]
    And just to go ahead and pimp some stuff here (although it really could make your life easier) we do have the brackets that we used on brandon's buggy rear axle as a "kit".

    [/ QUOTE ]

    You are the Devil. /forums/images/graemlins/grin.gif
     
  7. Greg72

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

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    Stephen,

    A quick search of your site shows nothing about this "4-Link Kit"


    You must reveal pricing or pics or something.....otherwise it's not "pimping" it's "teasing"....... /forums/images/graemlins/grin.gif
     
  8. Sandman

    Sandman 3/4 ton status Author

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    I believe Devils "Tempt" /forums/images/graemlins/deal.gif /forums/images/graemlins/grin.gif
     
  9. sled_dog

    sled_dog 1 ton status

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    yes and he sure is tempting us. hes been commenting about this 4 link "kit" for a while and said if you call you can get stuff. I am heavily considering it on the K5.
     
  10. Sandman

    Sandman 3/4 ton status Author

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    I wont be doing this anytime soon, but I will be doing it sometime. Going to get a few other things done first. I would love to have the rear coiled up. /forums/images/graemlins/grin.gif
     

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