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sagging leaf springs

Discussion in 'The Hokey Ass Message Board' started by hobiehunter, May 4, 2013.

  1. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    I have a 37 Dodge sedan with severely worn rear leaf springs. Completely flat with the shackle hitting the frame. Does anybody know what the stock ride height is and where is it measured from?
    I need to get some new springs that will give me a few degree rake but do I get stock or dropped springs?
    With some help and pictures from the members of this forum , several calls to fatman fab and some measuring the front end while lowered on a jack I have determined that fatmans IFS kit for the 37 dodge will work good giving me about a 3" drop in the front.
     
  2. Well, leaf springs are measured from eye to center pin & center pin to eye along the surface or arc of the spring. So you have that measurement.

    The arch height determines the ride height , but its almost always measured free with no weight.

    It's pretty easy to de arch new springs If they are too high. I just did a set today and it took about an hour for both springs. However figuring out exactly how much do was a bit of a pain and involved r&r ing them several times.

    You could give eaton springs a call
     
  3. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,284

    Kerrynzl
    Member

    Just get the springs re-set.

    A spring never loses it's rating for the life of the spring [ unless some hack job mechanic has "Heat treated" it ]

    Over millions of cycles it slowly loses it's setting.
     
  4. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,206

    Mr48chev
    ALLIANCE MEMBER

    As Kerrynzi said just re-arch them or have them re=arched. There is usually a spring shop around that will do it for a nominal fee or you can do it yourself by one or more methods.
     
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  5. rbonazzoli
    Joined: Feb 16, 2012
    Posts: 141

    rbonazzoli
    Member
    from Dallas, TX

    What does it mean to re-set a leaf spring?
     
  6. Re arch or put the arch back into into a flattened spring.
     
  7. GassersGarage
    Joined: Jul 1, 2007
    Posts: 4,729

    GassersGarage
    Member

    My girlfriend had a '63 Ford Fairlane wagon back around '69. The rear springs were sagging so her Father had a spring shop re-arch them back to stock ride height.
     
  8. rbonazzoli
    Joined: Feb 16, 2012
    Posts: 141

    rbonazzoli
    Member
    from Dallas, TX

    Thanks for the info.
     
  9. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    Judging by some of the modifications I've seen on this car I would not rule out the heat treating hack job.
    These are some fairly thin leafs, they taper down to next to nothing on the ends and are very pitted. I'll have to take them to a spring shop to see if they are salvageable.
     
  10. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,254

    Rusty O'Toole
    Member

    Just take the car to a spring shop and let them do the job. Old leaf springs are one of the nastiest things to work on.

    After 70 years the springs are due for replacement. This is not very expensive, about $200 bucks a set.
     
  11. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    The car will weigh about 1400 pounds in the rear empty.

    The spring load will be about 650 pounds empty.

    The spring rate will be about 110 pounds give or take 10.

    The rear frequency will be about 1.3

    The Arch will be between 6 and 7 inches.

    Re-Arching
     
  12. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    After reading eaton spring's explanation of re-arching leaf springs, mine do not look like they would be good candidate for the process. They are very pitted. The cost for the labor and parts required to re-arch may be equal to or more than a new set.
     
    Last edited: May 5, 2013
  13. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    6-7 inch arch, is that with the 1400 Lbs or with no load?
    I've got to do a little reading about leaf springs, rate, frequency.
     
  14. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    Unloaded, they should depress 1 inch for every 220 pounds or so (110 x 2).

    SO I would guess loaded an inch of arch. I don't much about this car exactly but all the cars in this weight class are set up similar, so those are the specs for a 37 Chevy standard.

    Standard cars have spring frequencies in the 1 - 1.5 range. F1 will be in the 3s.

    Here is a chart in CPM which is Hz * 60 do 1.3 Hz = 78 CPM.

    [​IMG]
     
  15. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    1936 Chevy Spring Info;

    [​IMG]
    [​IMG]
    [​IMG]
     
  16. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    Thats some good info on Chevy springs. I need to find something like that for 37 Dodge sedans.
     
  17. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    If you can measure them eye to eye, width, thickness and number of leaves, tapered or not we can get real close. Eaton can make you some they have the specs. Go to their forum they will answer you.
     
  18. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    Thanks for all the information hoop98. I did do a bit of reading about leaf springs this afternoon so I could be an educated consumer. A real fast eye to eye measuremenet showed about 55" There are 9 leaves total, 1.75" wide, 2" thick. The ends of the leaves are tapered.
    I'm gonna try to give eaton a call tomorrow.
     
  19. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    If that information is accurate those springs are lighter than I would have guessed. It makes a lot of difference on length and thickness.

    For example 9 leaves, tapered, at 55 inch and .222 thickness would be about;
    here is a table with slightly different lengths, thickness and how much arch you would need to be leave 1 inch of arch.

    Assumptions are 1200 pounds unsprung rear weight.

    [​IMG]
     
  20. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    I remeasured the springs, 53.250 eye to center bolt to eye. thickness of the 9 leaves is 2.125.
    I talked to mickey at Eaton spring. They do have springs for my car. He said the spring rate is 110Lbs. and free arch 7.75. Sooo if I'm thinking right and the rear of the car is ~1400 Lbs, 700 on each spring/ 110= 6.36" of deflection. Should be 1.39" of loaded arch.

    Just to get a baseline ride height with new springs I am thinking of putting a spring back in with a perch, 3" dia tube (to simulate axle housing), U bolts Etc and jacking the spring up until I get 1.39" of arch. Then measuring from center of tube to wheel opening. With this measurement I should be able to determine if I need to order lowered springs.
     
  21. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    You have to figure tires, wheels, and rear end, the springs don't hold them up. ~200

    So thats 5.5 of compression from 7.75 is 2.25 inches below the spring centerline. Try that.

    Width Number Thick -Length Calc Rate Load Comp CPM Hz
    1.75 -9 --- 0.2340 -53.5 --- 109.82 --- 600 --- 5.46 -80.42 1.34


    Hoop
     
  22. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    I put a spring back in and jacked it up to a point where the arch measured 2.25" and got a measurement of 17" up to the wheel opening. If that is anywhere near where the original ride height would have been I am definitely looking at a lowered spring. Probably 2-3".

    Posies has a 3" drop superslide spring they say has a 175Lb rate with 8 leaves .263 thick.
     
  23. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    175 is way too stiff.

    What is the measurement front eye to centerbolt?

    The running boards are going to be about 9.5 inches above the ground at the front, 10.25 in the rear in this pic of a 39. From the axle centerline to the rear wheel opening it is about 17.5

    [​IMG]
     
  24. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    I measure 24.625
     
  25. That's a cool picture right there.
     
  26. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    49-52 Look close

    8.5 arch so 2.5 under load

    [​IMG]


    56 Ford is the same length, 1/4 wider, same rate...

    [​IMG]
     
  27. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    This spring might be perfect, it'a 78-383.

    Would end up with about a 3/4 inch arch @ 600 pounds.

    [​IMG]
     
  28. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    Pulled the trigger and ordered the posies.
     
  29. hoop98
    Joined: Jan 23, 2013
    Posts: 1,363

    hoop98
    Member
    from Texas

    Yikes, better stiffen the front up 50 pct too! If they are 1 3/4 springs they are more like 135 if they are 33.5 long .263 thick, good luck...
     
  30. hobiehunter
    Joined: Apr 7, 2013
    Posts: 32

    hobiehunter
    Member

    Putting a MII up front.
     

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