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Coil Spring retention...

Discussion in 'The Garage' started by sled_dog, Dec 9, 2005.

  1. sled_dog

    sled_dog 1 ton status

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    I'm pondering coil spring retention for my 4 link project. I'd like to retain the springs on each end but this seems a difficult setup to do. I see with Russ' setup it looks like he just retained the spring at the bottom. Easy but is it really a good idea to let the spring free float? I mean won't a good bit of droop just let the axle fall out free? Granted the spring isn't doing much when stretched(except probably damaging it). My thought for the moment is the samething Russ did, with a limiting strap for if I care to get a little air. Thoughts here? I mean, free articulation is a nice thought but you can't control it with anything other then limiting straps and shock valving.
     
  2. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    Actually, mine has a limiting strap (as yet to be finished) that will stop the top of the spring right at the junction between the internal bump stop and the tube it mounts on. It will let the spring drop down about 4" or so. I did that so that it wouldn't hurt the spring, and the internal bumpstop assy makes sure it stays aligned when coming back up...

    Bottom line, I agree… :D

    Oh, and not only do I think free drop away is bad, but to much droop (or flex) in general is bad. I have no desires for a "ramp champ". I want predictable control, which means enough flex to keep all tires planted most of the time, so the shocks can deal with shifts, but only within reason so that you don't start getting into geometry and mechanical problems.
     
  3. sled_dog

    sled_dog 1 ton status

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    I'm expecting more compression travel than droop. Think I am wrong? Have the same springs as you. I think I will just do the same thing you did. Already made the top spring plate with a center guide, but it is only about 2 or 3" long, I'll sleeve some 1.75" inside of it and extend it down a bit for a guide and bumpstop location when I figure out how long that needs to be.
     
  4. ntsqd

    ntsqd 1/2 ton status

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    BD, do I understand correctly that you have ~4" of droop travel @ the spring where the spring is not in contact with it's seat?
    How does that behave on sidehills?

    I've always thot to keep the spring from getting loose at either end at full droop. My reasoning was that with any free-play btwn the absolute limit of droop and the total unloading of the spring is uncontrolled motion and could easily contribute to the sidehill flop. Sort of using the uphill wheels & tires as "anchors" to counteract a flop potential.
    So now you've got me curious if my reasoning was wrong and needs re-thinking. Can reason all you want, but if it works and isn't what you thot would work, then what you thot needs adjusting.
     
  5. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I'm not sure yet, since I seem to have been cursed to transmission purgatory (along with a large dose of lazy).

    But I should have said "max droop will drop the top away about 3-4" or so". My thoughts are at a minimum (first try sort of thing), to have adjustable straps that will allow me to constrain the axle as I see fit. Tip-toe through the boulder field, let it all hang out. Side hill, I can tighten the up-hill side if needed (depending on initial tests). Anti-squat jumps as you go vertical on a climb, so I could tighten both sides to allow only a few inches of down travel in that case. The only thing left to finish is the upper mount, which is where the adjustment will be.

    Also looking at one of the 2000 lb RV winches as a possible for a center restraint, particularly for climbing, and even have the ability to suck it down for decent as well. But, given my recent level of energy and activity, I doubt that will materialize until after I've had a chance to see how things work with the straps...

    But as for letting the spring drop off the top plate specifically being a problem, other than it rattling on the "guide" or something, I see no problem. At least it won't be like one of our TJ buddies chasing it down the wash when it pops out. :D Really no different than the coil-overs that have very light tender springs just to keep them tight. And it's better than stretching the spring to get that droop. To my mind, whether it drops free as mine can at the lowest mount point, has a 10 lb (or whatever) tender spring, or happens to have enough expansion to stay seated without going into stretch mode; if all else remains the same (i.e. CoG, amount of droop, etc.) it really won't make any difference I can see in whether you go over or anything else at that point. About the only thing I can see being much problem is if you had a shortish high rate spring that let you go from say 400 lbs / inch to 0 all at once. That might make things change a little too fast I suppose, but again, no different than the same scenario with a light weight tender spring.

    My current thoughts are that droop within reason, even without any more pressure than the weight of the tire (and it's suspension share) pushing down, has value in that it allows the shock to help control weight shifts. It's not about traction at all, but controlling weight shifts and limiting inertial over-shoot. I've seen several "surprise" flops and even a roll that were a direct result of violent shifts back to the side that had a tire "airing out", and that is what I had in mind when deciding on and designing this.

    A new and improved trans cross member (dusting off an old project) and the upper strap mounts is, at this moment, the only thing I'm aware of that is keeping it off the trails. Hopefully I'll be finding out very soon if it actually works.
     
  6. sled_dog

    sled_dog 1 ton status

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    a lot to think about... should have pictures of my setup by the end of the week(haven't started the suspension but has to be done within the next week and a half so should be interesting).
     

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