rear leaf springs

Discussion in 'Ranchero Tech Help' started by cbolt, Dec 4, 2020.

  1. cbolt

    cbolt In Overdrive SILVER MEMBER

    Messages:
    704
    Location:
    Palm Coast, FL
    I just completed a 8" to 9" swap and the car now has what I consider seriously stiff rear suspension. During the rear swap I also changed all the leaf spring bushings which were fairly worn out or missing most of the rubber. Because of the change in how the vehicle now rides I began researching leaf springs and saw in a video featuring Eaton Suspension a representative of that company suggested the springs for an 8" and 9" are somehow different and when a rear is changed the springs should also be changed to match the new rear end.

    Normally I would be skeptical of this as it seems on the surface like a marketing ploy but there is such a noticeable difference in how the car rides I feel there may be some merit to changing the springs.

    With that in mind I wanted to see if anyone here has any experience or information that would either support or contradict the need for new leaf springs to match the new rear end. Thanks in advance.
     
  2. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

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    New springs are not needed when changing the rear. That's a load of bull. That's like telling you that a spring change is needed when changing ratios. Spring rate changes are used to compensate for different loads, or different driving styles. The change you feel is the new bushings. Did you use poly? That always "stiffens" the ride a bit. Plus the positioning in the spring eyes after changing worn bushings to new re-centers the load to the middle of the eye instead of the ends of the eye(s) which can cause it to feel stiffer.
     
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  3. cbolt

    cbolt In Overdrive SILVER MEMBER

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    Alright. I thought it sounded like a marketing pitch but the car really does ride stiffer than I think it should. No, I used stock bushings, not poly.
     
  4. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    It's always going to be stiffer when the bushings are new, especially when the old ones are overworn, it's basically that you were used to the old ride. If it's that concerning, then get some 'tube sand' at HD or Lowe's, a couple hundred pounds or so, put it in back. It'll help exercise the new bushings a bit.
     
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  5. cbolt

    cbolt In Overdrive SILVER MEMBER

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    It bounces me out of my seat on the smallest bumps like I am on a dirt road all the time or something. Its fun at first, then gets annoying.
     
  6. pmrphil

    pmrphil In Maximum Overdrive GOLD MEMBER

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    Get the sandbags, you won't believe the difference, the springs can't move yet. And Andy's dead on at the weight needed.
     
  7. handy_andy_cv64

    handy_andy_cv64 In Maximum Overdrive SILVER MEMBER

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    Wow, that was just a WAG. Just make sure it's centered on the axle.
     
  8. 5.0 Chero

    5.0 Chero Bahumbug Staff Member

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    did you tighten the spring hangers while it was up in the air with the rear end unsupported? If so redo them with the weight on the rear axle the bushing may be binding.
     
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  9. cbolt

    cbolt In Overdrive SILVER MEMBER

    Messages:
    704
    Location:
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    I had it done by a local guy. Only guy I trust working on my car and since I wasn't confident I could weld the spring plates to the new axle tubes at the correct angle I had to rely on someone. Anyway I will start with sandbags and go from there.
     
  10. RancheroRandy

    RancheroRandy In Overdrive

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    The old sand bag trick is a start but note the angle of the shackles after each bag and if they never move or change angle than I would suspect the shackles/bushings are too tight...especially easy to do with poly bushings but not unheard of with rubber ones.
     
  11. Hillbilly

    Hillbilly In Maximum Overdrive

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    Carl is correct about when to tighten the bolts thru the bushings. Just like the front end bushings, you want the vehicle weight on the suspension just like if the vehicle was sitting on it's wheels on flat ground. If the bolts are tightened with the suspension or rear axel hanging, the bushings will be twisted giving them a short life and unnatural stiffness until they wear prematurely.
     
  12. Jeff B

    Jeff B In Maximum Overdrive BRONZE MEMBER

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    I had a '67 FiveLane Fairhundred wagon a looong time ago and any time it went on the rack, the rear shackles would flip forward and raise the back end of the car up. We had to re-rack it and pull the shackles in the other direction to get it to ride right. The shackles were kind of short and should swing top to bottom towards the rear of the vehicle.
     
  13. cbolt

    cbolt In Overdrive SILVER MEMBER

    Messages:
    704
    Location:
    Palm Coast, FL
    Ill post a pic tomorrow of my current shackle alignment and solicit input. When I first saw them I thought they looked a bit off in the way the shackles were in relation to the spring and vehicle.
     

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