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Stephen, talk to me about linked suspensions and frames.

Discussion in 'OffRoad Design' started by BigOrange90Jimmy, Mar 4, 2003.

  1. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    I'm putting coilovers on my Yota and I've been having some trouble brainstorming what kind and how many links I want to run on it.

    I'm using the stock boxed Toyota frame, and fullsize axles and I'm wanting to run coilovers. Right now, I can add more bracing to the frame if needed, because it's just a bare frame. The metal thickness is 3/32, so I'm guessing I will be welding maybe 1/8" steel to the bottom and sides of the chassis to give it some more beef. Think this will be overkill or should I use a thinner gauge metal?

    Now for the suspension talk. I'm wanting to be able to kick this pig down the highway occasionally, so I need it to be stable. I figure come here because I have no experience building anything like this, nor does anyone else around me. Sure, there are plenty of race car shops, but they don't think with gobs of flex in mind, so they're a lost cause. All I can do is weld, so we're good in that department! /forums/images/graemlins/thumb.gif

    Right now, I'm pretty much set on either a 16" King coilover, or a 16" or 18" Sway-A-Way. My point of view is, it costs the same, why not get the most amount of travel possible.

    I was thinking of running what I guess the "Pro's" would call a 3 link setup. I was going to run two links to the axle to locate them using a K link on each arm. I've seen it used on a Grand Cherokee and liked the idea of having the ground clearance of only 2 arms, but the axlewrap control of 4. With this setup, I would be running a panhard bar. Here's a ROUGH sketch of what I'm thinking of: K link

    What I've also seen is a "U" type 4 link (kinda). The sketch will explain better than my typing. U link

    The next one is a typical 4 link with the top links meeting in the middle. V link

    Or you can suggest one. I don't really care. The drawing board is blank, and I'm open to any suggestions. I've been looking at pictures of your suspension and I'm still trying to figure out what I need to do to work it out. Well help me out if you can. If not, I understand. Thanks bud!
     
  2. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You have a lot to learn, luckily you seem to know that. I think you should take a look at the pirate board for some link info, do a search on link suspensions and spend a couple weeks sorting through it.
    In general, the radius arm setup you described is not a good idea, they don't articulate well at all, and if they do they tend to break stuff.
    The 16" coilovers are nice but only because they are easy to limit down to more usable lengths. Most of the coilover setups I've seen "tuned in" are running more like 12-14" of travel. More is nice for go fast stuff, but for stability and climbing generally shorter is better. I have my 16's pulled down to about 14 now and it seems to be working pretty well. I'm looking into a swaybar also, that would be a good thing for you to look at when you're starting out rather than trying to work in later.
    I recommend King, I've been really happy with their service. With sway away, it comes down to what dealer you go with to get good service. Otherwise, for what we do the shocks are basically equivalent.
    As for frame reinforcement, you'll want to make sure to spread your cage loads over a wide area of frame to avoid tear out by using gussets and good cage design. In some cases you may want to add some plating to the mounting points to do the same job. Your link brackets especially will need a lot of though, they take a good bit of force.
    We may have some brackety available if you want to look at building a suspension like I have on my K5. I still have the info to build a couple different versions of the frame and axle brackets if you want to go that route. The front is pretty much a custom fab deal so far.
     
  3. blk87K5

    blk87K5 1/2 ton status

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    Go to the library and check out Race Car Vehicle Dynamics by Milliken and Milliken if you don't already have it. Awesome book. Kind of hard to digest, but it will answer 99% of any questions that you may have.
     
  4. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    Thanks for the replys fellas.

    Stephen, I have trouble seeing how these guys are getting such an amazing amount of flex out of a short (12-14")coilover. Is it based on them tilting the bodies in towards to frame? I know you can do this with shocks and it allows you to use a shorter one, but the amount of control is reduced.

    I have talked with Triaged in the Garage about this same post, and he agrees with you on that the radius setup is junk. After some persuasion, I am seeing how this is a bad idea. I love your suspension and decided I want to do something like it. I wouldn't mind slightly longer arms, but if yours works, then it's a plus. Either way I know I will not be able to replicate your setup in length and position, but only in design.

    King's are what I will be getting. At an amazing deal of $500 for a ready-to-run Dual Rate 14" coilover, I don't think that can be beaten.

    My cage is coming from All Pro Offroad, as well as the flatbed kit. I was planning on making an exo-cage and tying in the flatbed rollbars and the interior cage. Also, I will be running a fiberglass front clip, so I will have to run tubing up there also, so I think the frame will be plenty rigid when I'm done with that.

    I am extremely interested in the info on brackets you have for your suspension. And if you supply and sell heims, I'll get those from you as well. I need to actually use my membership on something. /forums/images/graemlins/deal.gif /forums/images/graemlins/rotfl.gif

    Thanks for your time bud! Be looking for me to order a Doubler maybe over the summer or sometime shortly after that.
     
  5. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Actually, most of the coilover rigs don't get that much articulation if they're set up right. A 14 or 16" coilover will get you about 18 degrees or so on each axle and that's quite a bit but nothing like some of the super-flex-triple-shackled-buggy-leaf-full-elliptic suspensions that may or may not actually work.
    Mount a coilover as far out as you can get it on the axle and as vertical as you can without letting the tire hit it and you'll be fine.
    We can get the heims if we don't have them in stock, and I've also started playing around with some of the urethane spherical bushings and they will probably work well if properly applied. We can thread any practical tube for the links and have some nice axle brackets too.
     
  6. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    18 degress huh? Don't have my protractor handy, but it doesn't sound like a whole lot. How are these guys doing competition with that? Sounds like a lot of tire-lifting to me.

    Anyways, I'll be getting up with you on the brackets and stuff when I get the cash to get started on it.
     
  7. NE-RokToy

    NE-RokToy Registered Member

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    18 Degrees sounds about right for a 14" travel shock mounted pretty much straight up. It may not sound like a ton of articulation but if your running full width axles and big tires you will have around 4' of total articulation.
     
  8. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    JESUS CHRIST! Is that 4 FEET of INDIVIDUAL wheel travel? That's insane, or at least to me it is. I LOVE IT! /forums/images/graemlins/thumb.gif
     
  9. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    I show 18 degrees gets you about 2 feet up on one tire with the other on the ground. That's before the other axle starts working so if it was all equal, you could get one tire up 4 feet and leave the other 3 touching. That's pretty good.
    There are variations in mounting widths of the shocks that change how it all twists up but generally control is making a comeback and shocks are the way to do it.
     
  10. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    What would happen if you mounted the shocks more inboard, instead of far out on the housing? Also, is it possible to get more flex out of it, or am I looking at 4' max with 3 tires on the ground?
     
  11. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You can bring the shocks inboard, you'll have to watch frame rail clearance and you'll lose some control but it will stretch farther. You can also go to a 16" shock to get some more motion but to be quite honest, 14" of vertical is a lot if you're set up right. As I've said before, I'm limited down to 14" or less on mine and it works fine. I'm adding a swaybar and putting more rebound damping in the front shocks to limit it some more. Keep in mind that the really crazy looking setups may not actually work that well in the real world, or for what you do. The biggest thing to stay away from is a big floppy monster.
     
  12. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    I ask if I can move them further inboard because I will be using a Toyota frame and body which is much narrower compared to the K5 chassis and body. I just didn't think it would look real kosher to have the shock stuck outside the fenderwell. I would retain the 14" shock, just move it in a couple of inches to keep the body of the shock at least in the fenderwell. I don't want it to flex like the Scorpion or Sniper vehicles. I guess that's just the image I have stuck in my head. I imagine I will be happy with the amount of flex it will provide. I guess that will be good for now. Have me some 14b and D60 link brackets ready pretty soon. /forums/images/graemlins/thumb.gif
     
  13. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    You should be able make that work. By the time you get them out of the way of the tires the upper mounts are probably only 36" across anyway.
    It's funny you mention the "flex" of a sniper. The one at TTC when I was there with the Bummer really surprised me how little it flexed. That was the year they had "Goliath", that super flexy triple shackled jeep that ramped like 1300 or something. Made the "flexy" sniper look funny. But it flexed good enough and had a lot more control. And they had the shackles clamped shut on the jeep for most of the event so it didn't have that much travel for real world use.
    Let me know on the brackets, we can cut them any time.
     
  14. Alaska Offroad

    Alaska Offroad Registered Member

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    This pic kind of shows how tight the shocks can get on front suspensions. I should have taken the pic with the lower coil on, but I think you get the idea.

    [​IMG]
     

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