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ride quality of de-arced leaf springs

Discussion in 'The Hokey Ass Message Board' started by happy hoppy, Jun 16, 2010.

  1. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    I want to do a static drop on my 1950 Ford coupe and I want to keep the nice ride. what is your experience with ride quality of lowering blocks VS de-arced leaf springs for lowering the rear?
    seems taking the arc out of the leaf springs will make for a stiffer ride. I have never liked the idea of stacked lowering blocks either, too many stories of blocks cracking. I did pick up a set of 1951 leaf spring shackles that are shorter then 49-50 shackles so that will give me about 1.5 inches to start with but, I need more drop.

    my car sits very HIGH, and it needs to come down a lot but not too much.

    I am not looking for a ridiculously low drop, no bags for this one. this is my daily driver and I am just not into the 4X4 look.

    [​IMG]
     
  2. Jalopy Joker
    Joined: Sep 3, 2006
    Posts: 26,946

    Jalopy Joker
    Member

    i had a '47 Ford coupe with stock front spring that was dearched with reversed eyes. rode good. to lower it a little more I took out a couple of springs. installed quality gas shocks. still rode good. you could always buy new springs made to lower it too. or put some bags of cement in trunk. do a search here for info on how to lower front with different springs, etc
     
  3. my 55 is running de-arched springs in the rear. it didn't ride too bad until i put traction bars on it, but since they're de-arched, the traction bar stoppers are always pushed up against the springs. it's a bit stiff now and the rear end will skate across little bumps in the road.

    but, the damn thing hooks!!
     
  4. RPaciotti
    Joined: Nov 17, 2009
    Posts: 29

    RPaciotti
    Member

    De-arching your springs will only change the free height of them, the rate will stay the same so the ride will be equivalent.
     

  5. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    29nash
    BANNED
    from colorado

    Yep, and the same is true with adding arch............
     
  6. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    thanks for the replies, I don't think cement is the fix, I am leaning towards a combination of 2" blocks and de-arced springs to get the amount of drop I want. I know some guys have used 4" blocks without problems but I think that's unsafe.
     
  7. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    bump for any additional comments, if you have done this please chime in and give your results.
    thanks!
    David
     
  8. NVScouter
    Joined: Apr 29, 2010
    Posts: 57

    NVScouter
    Member

    I disagree completely.

    I have zero experience with de-arching but I do have experience with re-arched springs and they are stiffer. Ride quality will change anytime the distance between spring eye's change. If the main spring length stays the same but the arch changes the eye to eye changes.

    It depends on how much slack/flex obviously but shackels can flip, bang, or if your shackel angle is 180* instead of 220* or so they can just fail to elongate. This sucks and can rip off shackel mounts and wipe out bushings.

    Also how are you going to de-arch? Take to a spring shop and have them de-temper and re-temper or do a torch job?

    But as far as blocks go I've seen steel work well if the plates and U-bolts are good but on heavy vehicles alluminum always fails. It only needs to start to wear a bit before you get movement. Your U-bolts will start wearing into your axle tube, shims move, and by the time you feel it its too late.

    Sorry thats my $1.05 on it. Changing the springs is the real sollution.
     
  9. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    29nash
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    Speaking from five or six decades of experience, including both of my current jalopies; Over time, as the springs lose arch, every five years or so, the eyes get farther apart, the shackles go beyond vertical. Even where the spring straightens out completely flat and the shackle is at a smaller angle from verticle.
    FRONT SUSPENSION.jpg

    When I re-arch a spring, the eyes get closer together, the ride is higher, but I have not experienced any noticable diff in rate. When re-arcing I want the shackle vertical at ride load.............. If I were to put so much arch in it that the shackle was over-center, it would then not be a spring, it would be locked up. Not a great idea................


    If I were to de-arch the spring where it was beyond flat to the point where the shackle was vertical, the rate would be identical to one with arch in it with the shackle verticle. ........except, my axle would come closer to the oil pan! The same holds true with rear springs of course...........just don't have a good picture of that.
     
  10. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    29nash, OK, I get it, keep the rear shackle vertical and my ride quality will not change.
     
  11. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    29nash
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    It won't change to the price of a hill of beans evne if it ain't vertical as long as the shackle can still swing...
    If it gets to that point where the spring can't bend due to shackle locking up, then you need longer or shorter shackle......
     
  12. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    29nash
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    from colorado

    .........even to the point where your spring is straight out. But of course beyond that you are going to be bottoming out and the u-joint yokes might be clashing or u-joint hammering the tunnel...........
     
  13. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    I am doing a small C notch in the frame and raising the tunnel so I wont bottom out.

    thanks!
     
  14. 29nash
    Joined: Nov 6, 2008
    Posts: 4,544

    29nash
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    You might get a kick out of this, it's an example to the extreme......
    A couple of years ago I was bottoming out, the rears needed re-arched, but I didn't have time to do it so I made longer shackles to get me through the summer...........................:eek:

    spring shackle.jpg
     
  15. SLAMIT
    Joined: Sep 9, 2002
    Posts: 929

    SLAMIT
    Member

    I really think that you would not have any problem with 3 inch aluminum blocks. I have used and definately abused quite a few cars with three inch blocks and never had a problem. Make sure that your U bolts are TIGHT!!!!!!!! I have seen a lot of problems with u bolts that re not tight enough and has caused the rear end to rock back and forth on the block or spring and cause big problems.

    I would even say a 4 Inch block is ok but make sure that the scrub line is ok you dont want to blow a tire and drag u bolts.

    Eric
     
  16. 40 Flier
    Joined: Jun 28, 2008
    Posts: 73

    40 Flier
    Member
    from Michigan

    My experience is lowering blocks = axle hop. I've removed 2" blocks from my 40 and eliminated a serious case of the hop. I'm looking to the springs to get it back down also.
     
  17. happy hoppy
    Joined: Apr 23, 2001
    Posts: 2,328

    happy hoppy
    Member

    thanks a lot everyone for the information. this will help me make an educated decision.
     
  18. Kerrynzl
    Joined: Jun 20, 2010
    Posts: 2,283

    Kerrynzl
    Member

    Firstly,I'd like to put my 2c in here.
    A spring, whether it's coil, leaf, or torsion has the same rating throughout it's whole life.
    But with millions of up/down cycles it slowly loses it's setting [ for example a saggy 80 year old spring with a rating of 250lb/in will still only move 1" with 250lbs load on it ]
    Re-setting a spring never changes it's rating [ but shortening it will ]
    There is also a difference between "wheel rate" and "spring rate"
    Wheel rate is lbs/in at the wheel via suspension geometry
    Moving a spring inboard on an A-arm alters the "wheel rate" [ moving the spring behind the axle on a suicide front axle lowers the wheel rate, if the spring is mounted on the wishbone ]
    Sometimes lowering the suspension can lower the "Wheel rate" [ a good example here is "laid down coilover shocks" on an early motorcross bikes.
    Ride quality is in reality "Spring Frequency or Stiffness" in laymans terms "Cycles per second"
    This is the relationship between "Sprung Weight" and the"Wheel Rate",
    For example If you dropped a big block into a 6 cyl car and simply re-set the springs to recover lost ride height [ you have actually lowered the spring frequency or stiffness ]
    If you did the opposite [eg removed 250lb's from the front] and re-set the springs at a lower height, the front suspension will be stiffer.
    There are 2 common methods for lowering leaf springs [ re-setting or lowering blocks ] there are pluses and minuses for both methods.
    Re-setting a leaf so it is flattened reduces "roll steer" [when one side of the diff moves rearward during body roll ] A flatter leaf is more resistant to lateral loads [ the arch doesn't want to "swing" sideways ]
    A spring with more arch has far better anti-squat which is better for straight line traction.[ thrust vs resistance creates lift to counteract weight transfer ]
    If you are happy with your ride quality, resetting the springs is the safest option
    Resist the urge to buy spring kits, Half of the "counter jockeys" selling them wouldn't have a f**ken clue about spring rating etc etc They usually just sell them as "street" "track" "slalom" "lowered" etc
    At least they come in a pretty box and are painted "yellow"

    If you really want to learn about suspension ,start hanging out with some dirt racers. These guys can perform miracles in a bad [dirt] environment. They know their suspension.
    Hope this aint too confusing
     
  19. 51 has a taller tunnel than a 49-50 if you want some additional driveshaft room. Pat.
     
  20. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,408

    atomickustom
    Member

    I had the stock springs de-arched and removed ONE leaf on each side on my '53 Chevy. It rode great. I later installed brand new Posies "Super Slide" (Super Glide?) springs on the car and it did not ride any better than with the original springs.
     
  21. 40 Flier
    Joined: Jun 28, 2008
    Posts: 73

    40 Flier
    Member
    from Michigan

    Since the poster signed off on this thread, (bear with me here, I've only owned coil spring cars for 45 years) I need to clarify. To lower parallel rear leafs, lengthen the distance between the shackles. A shorter "weaker" spring which lengthens under load would accomplish the same thing? What about flipping the eyes, does the main leaf have to be re-arched or will it conform under load? It's always nice to have some basics to avoid possible "okey dokes" at your local shop.
     
  22. atomickustom
    Joined: Aug 30, 2005
    Posts: 3,408

    atomickustom
    Member

    Huh?
    You don't lengthen anything - the flatter the spring is the greater the distance between the eyes. On an early 1950s car the arch isn't enough to make that matter much anyway.
    Flipping the eyes is a great way to lower the car IF there is no frame interference. I didn't mention it in my previous post, but I actually had my eyes flipped on my '53 Chevy along with the flatter arch and one removed leaf. It rode and handled great, but the front of the spring would clunk against the frame when you put it into drive because the flipped eyes brought the leafs and inch or so closer to the frame. The Posie springs have a flipped eye at the rear but not at the front. It handles lousy because it throws off the geometry. The front end wants to plow now because the rear axle is moving forward as it moves up. My car rides the same but handled much better with the flipped and de-arched original rear springs. Live and learn.

    There were no shackle or binding issues at all with either setup.

    No, you can't just flip the main leaf over and call it good. (Well, you CAN but it will not be right and who knows how low it will end up sitting?)
     

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