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88-98 SAS idea

Discussion in 'The Garage' started by thezentree, Jan 22, 2005.

  1. thezentree

    thezentree 3/4 ton status

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    So as I was driving home today, I started thinking about different ways to do SAS on my yukon. Instead of doing the usual leaf-spring conversion, why not do a long arm conversion? Not only would that completely eliminate buying anything from Off Road Unlimited (:whistle: ), but it would be way cool. What do yall have to say about this? I haven't researched this at all, but why couldn't I run a system like www.claytonoffroad.com 's hard arm system, a set of 94-01 Dodge 1-ton springs, and weld on some F-250 shock mounts? Any thoughts?

    EDIT: So I was really running late when I posted this, and didn't really go into detail. The Clayton system is a long-arm conversion for Jeeps. It's basically a long lower control arm that has a short adjustable UCA mounted about halfway down the LCA. It's not quite a true 4-link set-up, but it flexes like one and it's much easier to set up. Making the steering and trac bar would require a bit more thought, but as far as the suspension goes, I don't see why this isn't done more often.

    As for the coil springs (yes, that's what I meant), how is the Dodge upper spring mounted? Anyone have pictures?
     
    Last edited: Jan 22, 2005
  2. divorced

    divorced 3/4 ton status

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    Are you talking about coils up front? I think it's a great idea. Another member on here gave me the idea for my 1972 2 wheel drive to use coils all around to convert to 4x4. It already has them on the rear, and the front has the buckets. I plan to use a Ford D44 in front out of a coil spring truck with the radius arms and the 9" in the rear. Front with radius arms = NO spring wrap or wheel hop! Rear with factory control arms = NO spring wrap or wheel hop! It sounds good to me! If you are talking about something different than this, nevermind... carry on...
     
  3. sled_dog

    sled_dog 1 ton status

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    that clayton offroad site seems to suck. It still hasn't loaded. Installing a link suspension is a bit more work than a leaf sprung setup. Designing takes more work.
     
  4. sweetk30

    sweetk30 professional hooker Premium Member

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    if you give me your email address i will send you the same pics i sent to divorced for his 67-72 truck idea and this may help you in yours.
     
  5. ntsqd

    ntsqd 1/2 ton status

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    If you're thinking of a 4 link then you've got some ExcelCAD 2.1 work to do. Think of the Anti-Squat as Anti-Dive.


    If you're thinking of a radius arm system like the early 70's 1/2 Fords, then you're headed down the same track I've been thinking on. I've been on a EB list for a long time. Here's a couple things I've learned:

    Tracbar vs. draglink. Get them wrong and you've got bumpsteer.

    Longer arms are better. Less Castor change in bump. Pay attention to where the t/c UJ is relative to where the frame pivot bracket is, easy to build in a lot of plunge in the front driveshaft. Should be as horizontal as possible for best Castor curve.

    Radius arm pivot joint. The best really is the stock Ford rubber donut. The urethane donuts won't last a whole dezert race but the rubber ones will. A very successful stock Fullsize racer told me that. Could put an SRE there, but then you're translate a lot of NVH into the frame. A JJ might be a slightly better option.

    Tracbar pivots. SRE's don't seem to last unless they're HUGE or really high quality (=$$$). Urethane gets sloppy fairly quik (=DW). Maybe JJ's?

    Flex. For ultimate flex with short arms the arm furthest from the pinion wants to hinge at the axle housing or the housing needs a rotator cuff (Search "WAH" on bcbroncos.com). Though with a long enough arm neither is necessary.

    Coil-overs. 'Nuff said.
     
  6. thezentree

    thezentree 3/4 ton status

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    Post edited above.
     
  7. beater_k20

    beater_k20 Banned

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    ntsqd, can you use some more abbreviations in your next post?:screwy:
     
  8. divorced

    divorced 3/4 ton status

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    I'm with 'ya on this. What is a JJ? Actually, what are all of the abbreviations you used?

    Thanks.
     
  9. beater_k20

    beater_k20 Banned

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    JJ is a Johnny Joint, i caught that one, but it was one of the few.
     
  10. divorced

    divorced 3/4 ton status

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    I never heard of one. I looked it up though... EXPENSIVE! :yikes:


    SRE - Spherical Rod Eye

    t/c UJ - transfer case u-joint
     
  11. sled_dog

    sled_dog 1 ton status

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    Like he said, I don't know if either thezentree realizes what hes planning on getting himself into. Its not nearly a simple as bolting on some parts. ESPECIALLY if they are designed for another vehicle. There is a lot of math and work involved in 4 link, 3 link, and control arm suspension design. I am of the school that you don't have to do every damn calculation on earth to install one but just grabbing a bunch of parts designed for a Heep and bolting them on a full size Burb and hoping the geometry comes out decent is a huge no no.
     
  12. thezentree

    thezentree 3/4 ton status

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    No, I'm not talking about using the clayton kit, but using a design similar to that. I realize that an XJ crossmember is not gonna bolt up to my yukon's frame, I was just using that kit to illustrate the set-up I was talking about. I understand that there'd be a lot of fabrication and planning involved, and of course if I ever actually got around to doing this I'd research it more. But since there's only two links that actually attach to the frame, I figured it'd be a whole lot easier to set up than a true 4-link.

    Like I said, I don't really know what I'm talking about, but why couldn't the crossmember be mounted under the transfer case's front output, and have the LCAs swing in the same arc as the front driveshaft? That would eliminate binding in that area and would help protect the front driveshaft as well. Getting the caster right would be a little bit more involved depending on how much you allow the axle to droop, but I don't see why it would be so difficult to set it up if the axle wasn't allowed to articulate like a UROC buggy. As for steering and the trac-bar, why wouldn't a crossover set-up work as long as the trac-bar was parallel to the drag link? I realize it's a bit more than just grabbing some metal and gluing it together and hoping it comes out alright, but would that steering/trac-bar set-up work? And once that was all sorted out, it's a matter of welding some coil buckets to the frame/axle and getting the right shocks on.

    Of course that's an over-simplified version, and I'll probably never do this, but that's what the voices in my head are telling me. Do they know what they're talking about?
     
  13. ntsqd

    ntsqd 1/2 ton status

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    Certainly!! Where would you like me to start? :D

    SRE = Spherical Rod End
    t/c = transfer case
    EB = Early Bronco
    UJ = Universal Joint
    JJ = Johnnie Joint
    NVH = Noise, Vibration, Harshness; a term used by the OE's to define ride quality.

    Steering: W/o (without) using a bunch of linkage to and from the box and a bellcrank, Cross-Over would be a requirement.
    The ideal is that the drag link and the tracbar are the same length and parallel as viewed from the top and the front. You can use different lengths as long as the pivot points are such that the travel arcs are very close to each other through the suspension's range of motion. The more those arcs differ from each other, the more bumpsteer you will have.

    Front driveshaft: The radius arm pivots can actually be behind the t/c UJ point b/c (because) the pinion UJ is behind the axle CL (centerline). If you put the radius arm pivots directly under the t/c UJ you will likely compress and extend the front driveshaft more than if it were slightly behind it. My *guess* is that the radius pivot could be behind the t/c UJ by the distance that the pinion UJ is behind the axle housing CL.

    I had the same 'took forever to load' issue with the Clayton site. I think I know what it is they're doing, but can you post a pic?
     
  14. thezentree

    thezentree 3/4 ton status

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    I can't get clayton's site to come up right now either, they must be having problems. Anyway, I found an ORC write-up on their system: clayton hard arm


    As for the front driveshaft, mounting it behind the transfer case u-joint makes sense. Hadn't though of that....I have a lot to learn.
     
  15. ntsqd

    ntsqd 1/2 ton status

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    That is the kit I was thinking you were talking about. Digressing for a moment, putting that kit on an XJ would be a step backwards. It started out with a four link, changing it to a radius arm design just seems silly to me. Keep the 4 link since it's already there.

    The main problem I see with that design is that the upper links (which only control reaction torque and adjust static Castor) is that the point where they join the radius arm is just about dead center. Which wouldn't be too big of a deal if the arms had structure to handle the induced bending load. They do not.

    So, if you want to copy that, copy the concept and not the actual design. XJ's and ZJ's have tracbars too. The diagonal orientation of those uppers adds lateral bracing to the linkage. So the radius arms and housing want to hinge straight up and down b/c of the diagonal bracing, but the tracbar needs the axle housing to swing left and right in the range of travel. That is a formula for bind somewhere.

    If the upper links were inline with the radius arms then there would be no diagonal bracing and the binding possibility would move to the next design consideration. Likely that is the lateral deflection possible in the bushings btwn the housing and the arms/kinks. You can get a lot of flex deflecting those bushings, the longer the arms the more flex for the same amount of deflection.
     
  16. thezentree

    thezentree 3/4 ton status

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    I understand most of what you just said except for the last two sentences. Anyway, it's my understanding that the clayton kit works very well. I see what you're saying about it binding, but why wouldn't it bind the same way with the factory four-link? Anyway, if I do this, it's not gonna be crawling the rubicon, because it's still gonna be a tow-rig, so massive flex is not a requirement, but on-road ride is, and I've always heard that a link suspension rides better than a leaf-spring suspension IF SETUP PROPERLY. While the truck will still see offroad action, I'm not planning on following Willyswanter around in the yukon. I want to do this because it's something different. I've got a Jeep for the hard stuff.

    Anyway, back to the topic. I'm not following what you're saying about how the diagonal bracing would be any different than if it was inline with the LCA. Would the JJ's at the frame not allow enough lateral movement of the axle so that the track bar/drag link wouldn't bind? From looking at the clayton kit, the axle ends are simple bushings that allow the axle to pivot around an axis parallel to the axle centerline, and when both UCAs and LCAs are attached, this prevents the axle from pivoting around that axis at all. Correct me if I'm wrong, because I'm still new to this whole thing, but that is my understanding of it.

    As for the bending load on the center of the LCA, how would you brace that so that it doesn't see that load? Move the mount closer to the frame, so that the UCA is almost as long as the LCA?
     
  17. k5redneck

    k5redneck 1/2 ton status

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    i have a friend that has a 88 2wd truck that is running 1/2 ton dodge coils with a 4 link to a dana 44. it u want pics i will post them.
     
  18. thezentree

    thezentree 3/4 ton status

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    Yea, please do.
     
  19. ntsqd

    ntsqd 1/2 ton status

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    The factory 4 link has all four links running more or less parallel, they have no real lateral location function. By Clayton's angling their upper control arms they're giving them a lateral locating function, even if not intentional. The binding would be btwn the housing bushings for the radius arms and the tracbar. The housing end of the tracbar will want to swing in an arc across the vehicle, but with the diagonal links the housing mount for the tracbar will not be easily moved left to right. I suspect that the front axle articulates better in one direction than it does in the other due to the twisting of the housing relative to the frame moving the housing mount for the tracbar in the direction the tracbar wants to go. The angled links force articulation to compress the bushings, rather than twist within them. Compression usually takes more force than twisting.
    The various joints I've seen used for the radius arm frame end would have enough lateral dislocation possible that I doubt they would bind.

    That would be best. Could move it the other way too. The middle of any span is the worst place to put a load. Think about how you break a 2x4 for firewood. You don't stomp on it near the ends cause that really makes your foot hurt. You stomp on it in the middle because that's where it breaks the easiest.
     

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