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Leaf springs inverting

Discussion in 'The Garage' started by DaveCowley, Apr 22, 2002.

  1. DaveCowley

    DaveCowley 1/2 ton status

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    I am going to be upgrading to a longer travel shock probably a 9012 or the new 6 way adjustable Pro Comp MX6 shock. I have really two questions for you all and any help will be much appreciated.

    1. If I have more stuff than I currently have would there be any chance that the leaf spring would overcompress and invert slamming my tire into the fenderwell? I have heard of this happening so it worries me a lot with the increased flex.

    2. Has anyone heard anything about the new MX6 shock from Pro Comp? Price, Performance, reliability etc?

    /forums/images/icons/smile.gif See You In Moab
    http://coloradok5.com/gallery/88Jimmy(Blackout)
     
  2. Triaged

    Triaged 1/2 ton status

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    You don't want the spring to invert because it will weaken the leaves and they might crack or sag. I would recomend keeping the stock overload (and not flipping it) for the longest spring life. Extended bump stops are also a good idea.

    The ProComp adjustable shocks look good...but the longest travel they make (at least now) is 12" (32 extended, 20.25 callapsed). 9012's are 14" travel (and about the same extended length). 4wheelparts is selling them for $90 each for the "initial applications"...whatever that means.
     
  3. BorregoK5

    BorregoK5 1/2 ton status

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    I've heard of shackle inversion where you over extend the rotation of the shackle and have an unloaded travel circumstance but your spring rate should remain constant or even progressive, but not regressive unless it breaks.
     
  4. DaveCowley

    DaveCowley 1/2 ton status

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    I have already removed the stock overloads because they made my ass end sit up too high, I have ORD flip and I have done some hard 4wheeling in the last year but right now when at full flex my spring still is arched a little, it doesn't flatten out or invert but I am worried that with more upward travel that it might. What is the 9012's travel if you know off the top of your head?
    Thanks a bunch
     
  5. DaveCowley

    DaveCowley 1/2 ton status

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    So the rate should stay contant even if the spring is _-_ (at full stuff) instead of -_- (not flexed) or otherwise there is no way that the spring would want to reverse?
     
  6. Triaged

    Triaged 1/2 ton status

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    The rate isn't what you have to worry about...it is the bending of the springs. Think of bending a paper clip back and forth...it breaks. If the rear rides too high I would rather remove one of the other lower leaves than the over-load.
     
  7. DaveCowley

    DaveCowley 1/2 ton status

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    I see so it will weaken them or break them. That is what you are saying right? So if I want more flex then what would you suggest?

    Thanks
     
  8. BorregoK5

    BorregoK5 1/2 ton status

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    It sounds like your running a farily arched spring (4"-6" lift). At full stuff, what is the postion of your shackle, nearly straight back at 4 o-clock or 5 o-clock. Removing a leaf other than the main or overload is probably the best advise if you have a litle height you can afford to lose. Orbiting bushings at the springs ends could help reduce binding and get more flex as well.
     
  9. marv_springer

    marv_springer 1/2 ton status

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    Leaf springs will usually still provide a large percentage of thier spring rate when bent over backwards.... I'll agree that the life expectancy of the leaf spring becomes an issue when cycled from full arch to reverse arch, but usually the first sign of the spring dying is that is begins to sag instead of break.

    The answer to Dave's 1st ? is ... bumpstops. Bumpstops are an important part of any suspension and will prevent any "slamming damage".

    Marv
     
  10. DaveCowley

    DaveCowley 1/2 ton status

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    Really what I am speaking of is my stock rear springs because I am not too worried about the front Ranchos as I am pretty sure that they are designed for offroading unlike the stock rears. As far as the position of the shackle at full stuff would be about 7-8 o-clock from the passenger side since I do have the ORD shackle flip. You all seem to agree that the overload is a necessary part of the leaf spring but I only need about an inch lower and removing the overload achieves this for me. How much lower would I be if I removed the bottom leaf and put my overload back in? Maybe I should put the overload back in and get the ORD heavy duty shackles. Have any of you seen those L shaped shackles that I have seen a lot of people recently using I may fabricate a set of those that would put me up 1/2 inch or so in the front so that I could put in the overload.

    Thanks for the help

    /forums/images/icons/smile.gif See You In Moab
     
  11. Triaged

    Triaged 1/2 ton status

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    The only way to know how much lift you will lose/gain by putting the overload back in and removing a leaf is to try it.

    In the front your ranchos are stiff enough that you shouldn't be able to flex them enough that they would sag...but bump stops that work is still a good idea (one that I haven't done yet). On the back a overload will act to reduce axle wrap and act as a bump stop (again a real bump stop is still a good idea).

    You will gain 1/4" by installing the HD shackles in the front (87-91 blazers won't gain any lift because their shackle is 1/2" longer from the factory). If you made some 1" longer than stock you would gain 1/2". The only reason to make the shackle in a "L" shape is for clearance of something...I think you should just make them straight (easier to do too!).
     
  12. DaveCowley

    DaveCowley 1/2 ton status

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    Thanks, I think that I will probably put the overload back in but is there any point to the HD shackles if my Jimmy is an 88. You are saying that mine are the same length so when I really flex up they will hit too. What kind of ride quality and alignment problems would I run into with for example just a 1/2 inch longer shackle to stop it from bottoming out? I know you all are probably tired of answering questions but I really do appreciate the knowledge that you have. As for bump stops I still have the stock ones in the rear but I do have functional ones in the front actually two on each spring.

    Thanks Tons
     
  13. BorregoK5

    BorregoK5 1/2 ton status

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    Your not running any bump stops??? /forums/images/icons/shocked.gif

    Ok, I admit it... I'm not running any either... and worse yet, I've been jumping my truck. Not any bottoming out yet, and the front lands like a caddilac on those Ranchos, but its not good practice! /forums/images/icons/crazy.gif

    DaveCowley: The front geometry would change, but I'm not sure you'd be able to tell the difference. Triaged?
     
  14. Triaged

    Triaged 1/2 ton status

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    There isn't much point as you said in going to ORD's HD shackles. All they are is a bit thicker than the ones you have. I don't think your spring would bottom against the frame because AFAIK the upper piviot is in the same spot as a pre-87 blazer. It is just like they installed the ORD shackle (only a bit thinner) from the factory. The only issues w/ a longer shackle (if you want to gain some more lift) is the drivshaft pinion u-joint and the gain in caster (which won't be much as long as you don't go too much longer than factory).
     
  15. Triaged

    Triaged 1/2 ton status

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    I do have bump stops...the stock ones...in the stock location...and have been jumping it! I need to do something about that but don't have the time/money. When I install the 63" rear springs I will install bump stops that actually function (I will have to the way it will flex). For now my truck is stiff enough (ask Esteban!) that I probibaly don't get more than a few inches of stuff when I jump it.
     
  16. DaveCowley

    DaveCowley 1/2 ton status

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    Thanks again guys that should almost cover it for ride height. I have only a few questions on mounting my 9012's. If I were to mount them so that they were still the limiting factor on the stuff or in other words my springs would only stuff to the same place as now but those shocks would allow the opposite end of the axle to droop much further. This way there would be no considerations of tires not clearing when at full stuff. Would this be a waste of time or would it be a good idea to set it up this way. This is only a theory of mine and it may be wrong but I thought that I would bounce it off of you guys since you are pretty knowledgeable on engineering and such.
     
  17. BorregoK5

    BorregoK5 1/2 ton status

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    Just don't mount your shocks in a position where durring stuff you bottom the shock out (fully comress it) Leave yourself a bit of travel so you don't ruin the shock. As far as limiting factor. You might find as I did recently that the right size shocks at full droop wont be holding your axle up at all, but rather the spring will be your limiting factor(mine both stopped at the exact same point). You could put on shorter shocks but I'd stick with the flex as opposed to reducing it by hanging the axle on the shock. Try spacing your rims out a hair to keep from rubbing the stuffed wheel on the inner wheel well!
     
  18. DaveCowley

    DaveCowley 1/2 ton status

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    So you are saying that you would not limit stuff with the shock but say that I gave it a half inch to go then set my bump stop up there then the other side could droop a lot and yes I am sure that it would droop completely before the shock would top out. Thank you for the help and I will have pics up in a month and a half or so to show how I finally decided to set it up.

    /forums/images/icons/smile.gif See You In Moab
     
  19. BorregoK5

    BorregoK5 1/2 ton status

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    Cool, I look forward to it!
     

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