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Should I get new rear springs or....?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by TX Mudder, Oct 9, 2002.

  1. TX Mudder

    TX Mudder 1/2 ton status

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    I have a longbed pickup.
    Has 6" lift springs up front.
    Has 4" blocks and an add-a-leaf in the back.

    What should I do about it?
    I know about the shackel reverse, but I've figured that it will point my pinion too high and cause geometry problems. Basically, that it's cool for a blazer, ok for a shortbed, bad idea for a longbed.
    So, that leaves replacement springs.
    Is a 6" rear spring going to ride like crap? My front 6" springs are pretty rough.
    But then again, just getting rid of the blocks may be worth it.
    But then again, I don't want to loose all of my carrying capacity. I don't use my truck as a work truck per se, but I have no problem loading it down with some axles, an engine, motorcycles, whatever I need to. It is a pickup after all.
    I can't make up my mind.
    Also, going price for rears seem to be about $300/pair. Is there a better place to get 'em?
    -- Mike
     
  2. morphed86k10

    morphed86k10 1/2 ton status

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    God knows I think about this all the time.I really can't decide either. It boils down to how much carrying capacity you want to keep. Most lift springs are about the same as half ton springs. If your not unhappy with the ride, you might want to thing about some traction bars, they counteract the worst problem with blocks. And you can shim the pinion down a few degrees so that a shackle flip will work just fine on a longbed.

    I think I might do the shackle flip for now and keep the one ton springs for carrying capacity, then "flip" the ORD brackets and go with some custom ~60 springs in the future when this is just my off-roader.
     
  3. TX Mudder

    TX Mudder 1/2 ton status

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    I don't like the idea of shimming it down, but it may be the best way to go.
    I found this guy CLICK HERE
    who makes some strong shims in custom degrees.
    So maybe I'd use the 4" flip, the shim might add 1" or so, and then the add-a-leaf would be ratined. So it would be approx 6" lift afterwards.
    I'd like to get rid of the add-a-leaf, but I can't stand the idea of the bed being too low. With just the 4" block and add-a-lead now, it sits a little lower than the front. I don't like it.
    -- Mike
     
  4. afroman006

    afroman006 1/2 ton status

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    What do you mean shackles flips aren't for longer vehicles? I was plannin on doin the shackle flip on my Burban with the ORD Zero-Rates. I havent seen anyone say anyhthing about this before, why is it a no-no on longer vehicles? thx
     
  5. fourwheelerjeff

    fourwheelerjeff 1/2 ton status Staff Member Moderator

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    i would think the opposite would be true, the flip would work better on the longbed because with a longer driveshaft the angle would not be as severe as with a shorter wheelbase vehicle
     
  6. TX Mudder

    TX Mudder 1/2 ton status

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    Ok, let's think about this.
    To get 4 inches of lift out of a shackle flip, you actuially are raising it 8". Try to visualize the ORD 1" longer front shackles giving you only 1/2" of lift, but multiply by 8.
    Now that we've establ;ished that, consider the fact that the rear leaf spring front shackle is fixed - it's justthe rear moving down by 8 inches. That will tilt the spring and bring the axle with it. The axlehousing will rotate clockwise (if you are looking at it from the driver's side.)
    The pinion will go up, obviously.
    If you use a CV driveshaft then you can point the pinion right at the tcase yoke and it'll be perfect. But longbeds will run a non VCV driveshaft, so the pinion needs to be pointed down to make the axle angle closer to the tcase angle.
    If you don't, vibrations and short ujoint life are in your future.
    I currently have no detectable vibration and I really want to keep it that way.

    -- Mike
     
  7. 79Beast

    79Beast 1/2 ton status

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    Try the shackle flip with stock springs and add just enough block to make it sit like you want. As for shimming it down, it's not worse than shimming it up. The biggest issue is that you don't want to use shims and blocks. It is better to use tapered blocks. The reason blazers get more benefit from the added pinion angle is because they need the pinion pointed up more. Just match your pinion angle to your Tcase output angle and you'll be fine. Or since you are not having any problems now, just keep it the same.
     
  8. MJF

    MJF 1/2 ton status

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    Isn't towing & heavy loads a no-no with shackle flips? I thought I read that here, but maybe I pulled it out of my a$$.
     
  9. 79Beast

    79Beast 1/2 ton status

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    For a more complete explanation, search the ORD forum. The gist of it is that a properly designed shackle flip will use a hanger that is stronger than stock and will keep your "infinity point" the same. What that means is that when your springs are unloaded they have a slightly positive arch. When you load them they first get longer by flattening out. Next (as the arch becomes negative) they will try to become shorter. When this happens, the shackle is actually pulled uphill against whatever load you have. The spring rate goes up VERY quickly at this point. That's why it's called the infinity point.
     

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