Opinions on front control arm mods

Discussion in '80-Series Tech' started by -Spike-, Nov 14, 2005.

  1. -Spike-

    -Spike-

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    I've got a '94 with Slee's 6" lift kit. If you are familiar with the geometry of the front control arms and their mounts, you might be able to help me.

    Slee's control arm bushing 'sleeves' are wider than the stock control arm sleeves. In my estimation, this makes it more difficult for the front axle to articulate because the control arms cannot twist in their brackets- the top and bottom of the sleeves contact the brackets on the axle and on the frame mounts. I am curious if anyone has tried grinding the sleeves where they contact the brackets, to enable the arms to twist slightly. This would be a similar solution to 'wristing' the control arm, although easier and not as drastic.

    I am contemplating another mod, and this one will be even harder to explain, but hopefully I'm not the only one who sees the problem. The geometry of the front axle control arm brackets causes the control arms to exert a twisting force on the axle housing when articulating. This force would be in the axis of the axle- think of a giant attempting to 'wring out' the axle like a washcloth. I demonstrate this to people by holding my arms out in front of me simulating the control arms, placing a large book across my arms and then raising one arm. When the arms are not parallel, you can see that one corner of the book lifts off my arm. This is what happens with the four points of the axle that are held by the bushings. The mod I am contemplating is this: using one of my old control arms, cutting off the front bushing mount. This would be done to the passenger side, because I believe that it is the weaker control arm due to the path it has to take around the pumpkin. This mod would allow the axle to rotate on its axis without being twisted or 'wrung out' like a washcloth.

    Obviously, the reason for the bushing mount is to keep the alignment of the caster correct. Without the front mounts, the axle housing would be free to spin on its axis. The question is, would one mount be enough? Remember, the Slee control arms are much beefier than the stock arms. I would figure that for liability reasons Christo would not endorse this mod, but I'd like to hear his opinion anyway, and if he or anyone else has attempted this.

    I am aware that there are other factors limiting the articulation of the front axle. I am not trying to get more travel, I realize that at very least I would have to change the shocks to accomplish that. What I'm trying to do is relieve the stresses on the bushings, and therefore make it easy for the axle to articulate to its limits. I believe that would offer better traction and surer footing, less tipping when 'twisted up', and less chance of breaking or tweaking the control arm mounts, the bushings, or even the axle housing.

    Opinions?

    -Spike

    DISCLAIMER: this idea is not mine, but for simplicity of explanation I have presented it as such. I don't remember exactly who it was that brought it to my attention, but thanks.
     
  2. LukeO

    LukeO

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    I'd like to hear the answer to this one too.
     
  3. green_machine

    green_machine

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    well, IF I understand what you are talking about, this will have the same net effect as "wristing the arm"

    I would not do this your way though, as you will be increasing the leverage/force on the remaing mount, and also increasing axle wrap, among other things.

    I would explore a 3-link before I would go this route. There would be no triangulation in your design and would cause some real issues.
     
  4. CreeperSleeper

    CreeperSleeper SILVER Star

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    I don't remember the specifics, but this has been talked about. I know that there is at least two threads about it. (I know search is down and I'm not busting your balls for it, I'm just giving you some hope for finding an answer.) IIRC, I think someone has tried "wristing the arm", but I don't remember the results. HTH.
     
  5. LandCruiserPhil

    LandCruiserPhil Peter Pan Syndrome Supporting Vendor

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    Wristed arms will net a little more travel over non-wristed
     
    Last edited: Nov 14, 2005
  6. concretejungle

    concretejungle SILVER Star

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    But i think (either clown or tools) with a great write-up and pictures explaining that the gain of wristed arms is not much at all. Very negligable.
     
  7. SLC-Joe

    SLC-Joe

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    Hey, Im new here. Ive seen what you are talking about on a lot of jeeps and buggies and it works pretty well and youd get more flex for sure, but the 80 is way heavier. One issue you run into is that when the drivers side flexes down very far your steering ends up aimed right into the ground, but when the passenger side flexes down and the drivers side stays up then the steering stayes aimed forward. I dont know it the arms and mounts are strong enough but the principle is sound.
     
  8. fj803fe

    fj803fe

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    Not to totally beat this down as inginuity in designing greater articualtion in the front and rear axle is needed. But both are BAD ideas. Unless all you do is wheel your 80. The control arms are not THAT different in design-in fact I believe they are identical. Cutting the front bush mount is insane talk. Shortening the "sleeves" is insane talk. To convince yourself-do a test. Loosen the mounting bolts-even a little bit and allow the sleeve to "spin"/move inside of the brackets.

    Now drive around a bit-maybe even to 50-60mph---Like that vibration???-how about the "CLUNK" at stop/start? The flex you have in your rig (w/ stock bushings) is a function of the "give" in the bush rubber, with 'some' twisting at full flex.

    My mod-when I get around to doing it-is sitting in wait on two extra control arms (stock)-getting a couple of EXTREMELY heavy duty greaseable heim joints from Marylandmetrics.com and replacing the front control arm frame bush with them. As I don't want to wrist either.

    Another thought was to try to beg/bribe AOR or Alcan to design/machine their johnny/orbit-eye joints to press into the stocker arms... Still dreaming...

    IMO the outback control arms were great for this reason alone. It doesn't take much to drastically increase droop at the tire-a little relief here and some over there and I think you would be amazed how much the wrap-under conrtol arms will allow the axle to articualte.

    But, and also IMO, its best to keep things tight when it comes to coil suspensions-one piece out of whack and you can have a whole heck of alot of noise/movement under there. Moreover allow for just a bit too much tolerance between bolts/captures and you are going to be putting a bunch of unneeded impact force to the system. The #1 biggest reason I see sooo many heims go-is the match of bolt to capture diameters.

    my 0.02
     
  9. Nay

    Nay

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    I recommend you broaden your question. What do you need to accomplish? Are you constantly getting hung up on suspension mounts? Having difficulty on ledges even with lockers engaged when you have plently of clearance? Excessive lean on side slopes? Spending too much time thinking and web wheeling? Your post is all about function following form. Invert that and see what questions you still have.

    I'll give you some perspective (a nice word for opinion):

    What you are experiencing is the simple issue that by the time you are lifting to 6", the factory suspension design is not optimal, and bolt-on solutions often not only introduce undesirable characteristics, such as excessive lean in off camber situations, but are also often far more expensive than custom solutions. That MAF drop bracket kit is a perfect example. Proper design would raise the axle mounts, thereby increasing clearance, vs. dropping frame mounts, which reduce clearance and add exponential stress to the mounts and frame. But it is bolt-on, and that is what sells. If you think about engineering with the 6" taller suspension from scratch, you will *never* get the solution you choose with a bolt on suspension. Don't start with the factory setup if you want to get to the best answers. Maybe your first question is: did I really need a 6" lift in the first place? You could easily put 315's on OME by taking off the flares and redesigning the shock mounts.

    To your question, I would not touch cutting off one mount to create a 3 link, and I don't care how many people have done it. The secondary mounts in a radius arm setup control axle rotation. The 80 design has very little spacing between the two mounts, and this means you don't have a good leverage arm to control the motion nor have you designed that mount from scratch with proper bracing and reinforcement. I have heard that in a 3 link you want at least 8" of vertical mount separation between the upper and lower mounts to properly control axle rotation. Remember what happens if the 3rd link fails: the axle will rotate upwards, sending the driveshaft into the body and probably dislodging the spring mounts entirely.

    I can't imagine what you gain when you intend to keep everything else the same.

    Nay
     
  10. sleeoffroad

    sleeoffroad Supporting Vendor

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    Have you ever tried to wheel it without swaybars?
     
  11. TiredIronGRB

    TiredIronGRB

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    It seems to me that you could make both ends of the control arm swivel like the rear of some of the custom ones do. Why hasn't anyone done this?
    frontarms.jpg
     
    Last edited: Nov 14, 2005
  12. green_machine

    green_machine

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    I think christo is trying to send you down a correct path. Travel is relative. I think you may or may not know that you are only going to get sooo much travel with radius arms, it's all in how it's controlled, or how fast it feels. I once had my rear three linked vehicle with virtually unlimited rear travel, but I had axle steer out the arse, and it would flex way tooo fast. You really should trying some other things before you go fabbing axle mounts.

    Things like discoing the sway in the front ONLY, and not retaining the springs. Then try it with the sway disco'd and then retain the springs. After that, retain your springs, and go to a 14-16 inch travel shock.

    retaining your springs with long travel shocks will do wonders under FORCED ARTICULATION.

    Rovers have the same front end, with the exception of a rose joint for the frame side of the arms. johnny joints, heims, shperes et al have been tried. If you need more than 14", build a new suspension.
     
    Last edited: Nov 14, 2005
  13. Tools R Us

    Tools R Us

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  14. Josh83

    Josh83

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    Has anyone in the US done the flipped arms yet?
     
  15. jmaddocks

    jmaddocks

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    There's a good discussion on wristed control arms from a few months ago at https://forum.ih8mud.com/showthread.php?t=56748&highlight=wristed+control . The dominant source of the binding is not the twisting of the control arms themselves, but instead the eccentric deflection of the control arm bushings as the axle articulates. Replacing one or more of the bushings w/ a heim would further reduce this eccentric deflection and probably make things worse.

    On the road, I run my LX450 w/ a receiver hitch pin in place of the right front control arm bushing bolt (opposite the side shown in the link above). I remove the hitch pin when I air down at the trailhead. The difference in articulation is significant -- I can stuff one side to the bumpstops while the other is at max shock extension. To reinforce the control arm mounts (which were obviously designed with both control arms sharing the axle torsional loads), I've got Slee caster plates welded to the control arm mounts for more stiffness, in addition to their normal caster-correction duties. On the non-wristed side, I have welded additional 3/16 in. plates to the sides of the caster plates which are in turn welded to the axle to help prevent the control arm from ripping off. I had to grind about 1/8 in. off the wristed control arm to prevent interference w/ the tie rod.

    I've driven short distances on-road w/ the hitch pin out, and the truck leans A LOT. It's not uncontrollable by any means, but I wouldn't want to have to perform any evasive maneuvering at highway speeds. I don't think it'd be a good idea to cut the front bushing mount completely off on anything but a dedicated trail rig, though it might be workable combined w/ a sway bar w/ quick disconnects.

    Yesterday I returned from Panamint Valley Days, a pretty big Cal Assoc of 4WD Clubs event w/ all-day runs Fri - Sun. I kept a close eye on the control arm mounts, and they seem to be holding up just fine. I see myself as a bit of a guinea pig w/ this setup and hope to give a follow-up report after a year or so.

    Jason
     
  16. Josh83

    Josh83

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    Could you post pics of how you beefed your castor plate? I'm having a little trouble visualizing what you have done.
     
  17. Tools R Us

    Tools R Us

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    Not that I have seen?
     
  18. jmaddocks

    jmaddocks

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    Just ran out to the driveway to take a quick pic in the dark. It didn't turn out too well because of the flash, but hopefully you get the idea.

    Jason
    control_arm_mount.jpg
     
  19. Waggoner5

    Waggoner5 SILVER Star

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    I think that the bottom line is that most of this has been tried, and found that there are some mods you can do to the existing 80 front system that will help, but how much will it help? What compromises will you mod give you in other areas?, and best of all, how serious of trails are you really going to take a 6k lb. station wagon where killer articulation (or an extra 2" of articulation) makes or breaks your trip? I have watched well prepared 80s run some really nasty trails with nothing more than a properly setup "off the shelf" suspension. Another 1" or 2 of articulationw ould have done nothing. The 80 front with swaybars disconnected for trail use, works better than most wildly modified front suspension systems. Christos arms are the best off the shelf fix for keeping geometry correct on 4"+ trucks, but are no way as strong as the stock arms. They are as strong as you will ever need though. The biggest articulation stopper on 80s is the aftermarket caster correction poly bushings in the front arms. They flat don't flex nearly as well as the facory rubber. Purchase Christos arms with rubber bushings, disconnect the sway bars, lock the lockers, turn on the AC, and go wheel.
    G
     
  20. clownmidget

    clownmidget

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    I agree with what Gary is saying except that the OME poly bushings part. They will still flex enough to let the stock arm bushing ring contact the axle mount bracket and bind.

    But Gary is correct in that you can get the front axle to drop to the full extent of the OME L-shock, a completely off the shelf bolt on setup. That's about 12" of shock travel extended or 28" from the upper shock mount to the lower axle shock mount. So if you want more than that, "Why?" If you have valid reasons then go to a real 3 or 4 link and be done with it. Christo's arms most important fxn in my book is it lets me run the 6" springs, get the full range out of the OME L-shocks AND lets me drive on the freeway safely with 35's going 70.

    Ok, maybe I go faster than 70 sometimes...


    Oh, and didn't anyone do a search and find the crap I did with the forklift? Talk about not gettin' any props!
     
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