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Technical Need advice on how to fix a bounce rear end

Discussion in 'Traditional Hot Rods' started by Lowbow38, Oct 23, 2020.

  1. Take the Lowering Block's out & it will Ride Great!

    Just my 3/5 cents

    Live Learn & Die a Fool
     
    deathrowdave likes this.
  2. ...if the u-bolts were the correct length, there wouldn't be a scrub issue...
     
    Just Gary likes this.
  3. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    Thank you all for giving me insight in what I need to look at and figure out and fix. I’m going to see what I can do about getting the leaf springs from being flat and I will cut the ubolts down so they aren’t that close to the ground. There’s a lot of work that still needs done on this truck. I was also thinking about removing the leaf spring set up all together and C notch the frame and put a 4 link system in to.
     
    Last edited: Oct 24, 2020
  4. Weedburner 40
    Joined: Jan 26, 2006
    Posts: 954

    Weedburner 40
    Member

    Also, your shocks original application if 63 to 82 Corvette IRS, so they are valved stiff. The springs are going to be stiff as their original application is a Dodge four wheel drive pick up front spring. Eaton-Detroit does make a replacement spring for the CE application that works much better, but they aren't cheap. Hope this helps.
     
  5. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    I do have a question about the leaf spring pack itself. One the top leaf I have one eye that is pointing down and one that is pointing up, how should I have the eyes when everything is bolted up? Also I noticed that at my center point of my leaf springs that the leafs are longer in one direction. What direction should I have the leaf with more material going. Sorry to have questions that might both you all, I’ve been a VW guy for ever and I’m just getting into old fords
     
  6. Questions don't bother anyone here. Everyone is more than happy to help. The only flack people get is when they have already made up their mind about how to do something, ask anyways and then argue with the advice given if it doesn't match what they had already decided to do. You are trying to learn and have a good attitude about it. You will get lots of help.

    Sent from my SM-G950W using The H.A.M.B. mobile app
     
  7. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,770

    olscrounger
    ALLIANCE MEMBER

    Lots of good info given--the eye on the end facing down is a reversed eye-lowers about 1 1/2? maybe
    Weedburner 40 above can fix you up with the right parts I'm sure--used many of his parts on 40's
     
  8. Atwater Mike
    Joined: May 31, 2002
    Posts: 11,625

    Atwater Mike
    Member

    ONCE the geometry gets 'adjusted', take note of shock rates. Monroe shocks come in variables: 10/90, 20/80, etc. We found on light cars ('28-'32 fenderless 1800 lb. typival) a 30/70 shock worked best. (30 'easy' in, 70 'hard' out)
     
  9. Happydaze
    Joined: Aug 21, 2009
    Posts: 1,903

    Happydaze
    ALLIANCE MEMBER

    Ref the unequal lengths of the spring from the 'center point', it makes no difference, as long as the wheels are where you want them to be in the arches - and the same on both sides, naturally!

    Chris
     
  10. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 6,250

    Ebbsspeed
    ALLIANCE MEMBER

    After a couple flat tires at speed the scrub line will be OK.
     
  11. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    I’ll take care of those Ubolts once I get the rear end suspension dialed in
     
    bchctybob likes this.
  12. Country Joe
    Joined: Jan 16, 2018
    Posts: 517

    Country Joe
    Member

    I have a Chassis Engineering leaf spring kit on my car. I took the smallest leaf out to soften the ride but, it got very bouncy as you described. I put it back in and it settled down. I also called CE and they told me the correct length the shock should be as it sits. I was bottoming out due to the shocks being too compressed at rest. I corrected that and it works great now.

    And, my springs are also longer from the leaf pin forward than back.
     
    Last edited: Oct 24, 2020
  13. Almost always, the longer side of a leaf pack is to the rear.
     
  14. grumpy65
    Joined: Dec 19, 2017
    Posts: 920

    grumpy65

    :D:D:D That's funny.
    Exactly what I was thinking......................a self-remedying problem.
     
    olscrounger likes this.
  15. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    So I’m going to do a couple things to see if I can fix this issue, I’m going to put the leaf back in that took out and I’m going to modify the shackle bracket and move the mount forward a inch to see if that corrects my issue, I’ll take a better ride than the stance I have any day.
     

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  16. Mimilan
    Joined: Jun 13, 2019
    Posts: 1,230

    Mimilan
    Member

    That is a contradiction !
    Shorter springs are stiffer.

    If the springs were too soft, it wouldn't bounce until the suspension bottoms out.
    Having the axle that will arc forward is a desirable quality. It promotes roll understeer and is stable.
    The only major difference with a reverse arch is behind the axle [the shackle swings forward during compression]


    The OP needs to get a tape measure and measure the shock length at ride height.
    Then deduct enough length for when the axle hits the bump stops [allow for shock inclie axlenation]

    The Monroe 33033 shock has a length of 10.125" when fully compressed
    It could be bottoming the shocks out before the axle hits the bump stops.

    Also he should remove the bump stops and take it for a ride.
     
    Last edited: Oct 25, 2020
  17. grumpy65
    Joined: Dec 19, 2017
    Posts: 920

    grumpy65

    The smart option.
    If you can't drive it because it's too low, you could have saved a lot of money by just taking a picture of it to hang in you garage instead...................;).
     
  18. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    With the rear end there is really only about an inch of travel when trying to make it move, basically when driving down the road the rear end feels so still that it feels like the whole back end of the truck is bouncing but not due to the suspension, never once have I heard a bang or a clunk sound with the axle hitting the frame. It’s almost like the rear end has no movement at all with or without the shocks
     
  19. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    The back end isn’t to low, this is how it’s stance is now, the front is much more lower and it handles pretty well, but the back end is stiff as hell. Would think that even removing the shocks I’d have a lot of movement but it feels the same
     

    Attached Files:

  20. grumpy65
    Joined: Dec 19, 2017
    Posts: 920

    grumpy65

    upload_2020-10-26_10-24-43.png

    Can we get some close-ups of this area?
     
  21. Mimilan
    Joined: Jun 13, 2019
    Posts: 1,230

    Mimilan
    Member

    If you want to fix it [without machine gunning $$$ at it] you will need to try a few things and also measure a few things.
    Measure the shock travel as suggested. [it costs nothing]
    Also remove the bump stops [rubber bump stops dont clunk like steel ones]

    A car will squat more than 1" under gentle acceleration ,so it could be constantly sitting on the bump stops.

    Remove the lowering blocks [Just to see if the ride improves, and there is no binding]
    If the rear is still too bouncy with the lowering blocks removed, it usually means the frequency is too high [too stiff for the suspension load]
    If that is the case, then load up the bed with some weight to see if it goes away.

    If the springs are too stiff, then the best remedy is to soften them by removing a leaf, then re-arching them to restore spring load.
    If you have to do this,you might need to add "override bars" to prevent spring wrap!

    You really need to use a tape measure before and after when doing this sort of suspension tuning.



    edit: In suspension terminology , spring stiffness is the spring rating [lbs/in] eg: a 100 lb/in spring will compress 1" with 100 lbs on it, and the same spring will compress 3" with 300 lbs on it. [unless they are progressive rating]
    Spring load is the unloaded height [or shape] , You can have a 100 lb/in spring designed to carry 700 lbs. It is shaped to settle 7" when loaded [this explains why spring compressors are needed for some installations]
    Softer springs are usually longer or have a deeper arch
     
    Last edited: Oct 25, 2020
    Lowbow38 and grumpy65 like this.
  22. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    I can get pics of that area tomorrow and post them
     
  23. Rickybop
    Joined: May 23, 2008
    Posts: 9,605

    Rickybop
    ALLIANCE MEMBER

    I kinda like a bouncy rear end.

    Had to say it. :p

    Saw your thread a couple times, Lowbow38. Good to see all the help. Good luck.
     
  24. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

     
  25. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    I hope I can get it figured out. It’s driving me crazy
     
  26. grumpy65
    Joined: Dec 19, 2017
    Posts: 920

    grumpy65

    Follow any advice given by @Mimilan . This is one of the members on here that will really be able to help you out.
     
    Lowbow38 likes this.
  27. gene-koning
    Joined: Oct 28, 2016
    Posts: 4,040

    gene-koning
    Member

    Sorry, but my statement is not a contradiction. Though generally, a shorter spring is stiffer, not all short springs are stiff. The number of leafs in the spring pack, and the thickness of the spring leafs determine how stiff a leaf spring is, not the length of the spring.

    Besides that, my comment was based on what I see with his spring and shackles. With the leaf spring higher at the center then it is on the ends, the shackles have to be able to move forward for the leaf to function. The way his are will not ever function correctly. If his springs were higher on both ends then they are at the center, the spring and shackle set up he has would be working correctly, but his spring has the arch going in the wrong direction for his shackles to work as it currently is. Then we would be talking about shocks and bump stops. Doing anything short of correcting the leaf spring and shackle set up he has, will not have any effect on his problem. Gene
     
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  28. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    Found the paperwork with the specs of my leaf springs
     

    Attached Files:

  29. gene-koning
    Joined: Oct 28, 2016
    Posts: 4,040

    gene-koning
    Member

    And that is how your springs should look with them mounted on your truck, but they don't. If they looked like that, they would probably work correctly. Gene
     
  30. Lowbow38
    Joined: Mar 24, 2020
    Posts: 57

    Lowbow38
    Member

    In the next couple days I’ll take everything part and mark everything where it is now and take photos and post them on here, hopefully with everyone’s help I’ll be able to figure out this problem
     

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