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Technical Softening a harsh ride

Discussion in 'Traditional Hot Rods' started by Low-N-Loud, Mar 20, 2017.

  1. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    I get it. I definitely have seen coilover setups on early rods that look hideous. But I've seen great looking ones too. Def not for everyone though.

    But like I mentioned before, I'm still waiting to hear back from a couple shops about a new front spring. So we'll see where it ends up. As indecisive as I can be at times it's always up in the air until something's "finished".


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  2. mcsfabrication
    Joined: Nov 26, 2006
    Posts: 791

    mcsfabrication
    ALLIANCE MEMBER

    If you get the buggy springs set up properly, with shocks, it's hard to beat. And you're 3/4's of the way there already. You just need to dial it in.
    If you choose to go the coil over route, you'll end up "tuning" that in also.
    I'm kind of lazy, and would work with what you have quite a bit before trashing it.
    Get the shackles in the front above the scrub line, measure everything so you end up with shackles at 45 degrees, decent pair of hot rod shocks and get your main leaf made up. A few of the shorter leaves out and you could be test riding, and finessing on a good Saturday.
    Best of luck.
    Did I mention that I'm cheap also!
     
  3. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    I'm not cheap, and I'd still stick with the cross springs.
     
    shawnsauto1 likes this.
  4. Roupe
    Joined: Feb 11, 2006
    Posts: 719

    Roupe
    Member

    I think you mean his Ackermann steering geometry is messed up because of the tie rod out front.
     
  5. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    Very valid points. I think maybe I'm just a bit thrown off because I know how stiff the car rides now... hard for me to imagine it riding good at all. My car experiences outside of this truck were / are modern cars with modern suspension systems so thats my only basis. But there is something to be said about all the guys running around with traditional setups, can't be all that bad then haha.

    @gimpyshotrods looks and amount of work aside, what's your reasoning for sticking with the leaf springs? Just curious if from an engineering standpoint there's something about them you like better?
     
  6. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    You are nearly finished fixing your issue.

    Starting over now is a waste of time and money.
     
  7. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    While that is certainly true, he can fix that in under an hour, with hand tools.
     
  8. tltony
    Joined: Jan 11, 2009
    Posts: 269

    tltony
    Member
    from El Cajon

    Your original post said you were trying to smooth out the ride. Stay focused. Based on your bouncing video, IF it were mine, I'd start by taking out 3 or four leaves from the front and try it. It should bounce freely down the road, then add some shocks. Try the same on the rear. Add panhard bars as dictated by sway.
     
    46international likes this.
  9. Those springs need to mounted with a bunch of pre-load tension.
    Doing that flattens them. Flatter springs lowere you're ride height.
    The problem is that the perches are too close together
     
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  10. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    I'm not following? The ride height is fine. Spring is an original that's not really letting the leaves slide, and it's too long (90 shackles instead of 45 under load). So bad ride quality ensues.

    Maybe I'm missing something?


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  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    In the original intended arrangement, for this model of cross spring*, the spring was intended to be forced into position by a spring spreader. (Shown here on a rear spring. It's the black thing, with the red ends.)
    [​IMG]
    And then attached to the shackles.

    With no load, this would leave the shackles horizontal.

    With full chassis load, this would leave the shackles at 45º.

    That tension locates the axle side-to-side. You do not have this tension because either your main leaf is too long, or your axle perches are too close together, or some combination of the two.

    You have slack shackles. That allows the front axle to wander side-to-side, making for a dangerous ride.

    As others have told you, you should have a shorter main leaf, or possibly a whole new front spring.

    Also, as has been hinted at, you should take the steering arms off, switch sides, and put the tie rod behind the axle, bending the steering arms down as necessary to clear everything else (or getting dropped ones). If you do not do this, there is simply no way that you will achieve the proper Ackerman Angle. Not fixing this could cause you to wipe out in a corner. It might not, but why play Russian Roulette?

    *Later models of Fords and Lincolns had slack shackles, but they also had a panhard bar in the the front, to locate the axle.
     
    Low-N-Loud likes this.
  12. Yes you have the cart before the horse in your thinking .
    Your symptom is, "harsh ride", your problem is no pre load tension, the cause is the perches are too close together.

    Here's how it's supposed to work.
    Take the spring, add pre load the tension in by flattening the spring and increasing the eye to eye measurements. You should have to stretch the spring to mount it. With no load on the the spring, but under quit a bit of pre load tension the spring pulls the shackles in a straight 180 relation ship. It's enough to hold the weight of the axle assembly up.
    Here you shackles should be parallel with the tie rod, pulled tight.
    image.png


    So you may say to yourself , "well self- the perches are where they are and I'm not moving them, I need shorter springs to mover this towards correction" ok great! Now when you get a shorter spring and add that preload tension by flattening it, well there goes the arch height and the ride height depends on ------- the loaded arch height.

    Theses transvers springs operate differently, on a different theory than regular leaf springs. That's because of the preload tension. The shackles resting loaded at 45* is a visual check that the pre load tension plus the spring rate (force up at center mount) and vehicle load weight (force down at center mount) are roughly equal. If the shackles are more vertical there's not enough preload tension or not enough spring. If the shackles are more horizontal there's too much preload or too much spring rate.

    With the balance achieved , the shackles will tell you and the ride is quite nice because of that balance.
     
    David Gersic and Low-N-Loud like this.
  13. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    Based on your measurments, I believe that the closest that Posies could get you would be a

    580-1002 or 580-1002L. The second being about an inch lower, which I do not recommend.

    Do us a favor and measure from the lowest point on the spring eye, down to the ground, and also the lowest point on a front wheel lip, down to the ground.

    If the spring eye is closer, you have a safety issue. If not, carry on.
     
  14. One of the problems is You've got the same problem with preload tension back here.

    image.jpeg

    What is going on back here?
    The rear radius rods as built will probably get someone hurt.
    The rear Z is obviously at least 6" too tall.
    Drop it or make a neat looking deep drop crossmember to catch the spring
    image.jpeg
     
  15. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    Wow my head hurts now haha. Tons of great info, thank you guys. Really starting to understand this more.

    With all of that in mind though, how do I determine what size spring I need? Because I think I would definitely want a new spring. Just so I know it's working as well as it should. Is it as easy as going shorter? Now I'm concerned with all the pre load talk. Am I going to need one of those spreaders when installing the spring?

    So many more questions now.... thanks for the hand holding.


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  16. nrgwizard
    Joined: Aug 18, 2006
    Posts: 1,100

    nrgwizard
    Member
    from Minn. uSA

    Hey, LnL;
    Lots of guys have given you really good advice on this thread concerning the leaf n shackles deal. All you gotta do is follow it. Well, that n some personal labor. You've already got almost everything you need already, so's expenses will be kept fairly low, & stuff'll work well when finished.

    Look, 1st: talk to the spring guy(s) & see if they can shorten & re-arch your old springpack. If not order one that fits the #s from steps 2 to 5, they'll guesstimate the spring-rate for you, using the weights& heights/lengths you provide. If they will work w/the old stuff, follow steps 2 to 7.
    2nd: set the front frame horns to the height desired,
    3rd: get the shackles out of the scrubline,
    4th: set the shackles to ~ 45* & measure the horizontal distance twixt them. Note that.
    5th: note the vertical distance from the shackle bolt line to the underside of the spring perch. This will give you the arch height & spring eye length of the spring pack, under lo
    ad, that you want.
    6th: I'd disassemble the spring pack, de-rust it, grind any rust n ridges/wearmarks off 'till smooth.
    7th: send off springpack for rebuilding.
    8th: after getting springs back, (assuming they shorten & reroll the eye of the main & re-arch all of them), round off corners n grind a bit of taper on the underside of each now-rounded leaf tip.
    9th: paint the leaves.
    10th: I'd start w/using the main leaf, 2nd leaf, & every other one. Be sure to use the proper spring clamps. If you need more height (fine tuning), cut the shortest leaves to ~ 6" long to use as spacers. If leaf-pack is still a bit stiff, pull the shortest leaf & try again.
    11th: once the leaf-pack is determined to give a decent ride, finish the job by either using a plastic liner twixt each leaf, or the old way of alum window screen filled w/axle grease to minimize friction. If greased, wrap w/a couple of layers of electrical tape (or a leather sleeve) to keep dirt out.

    This worked well for the R&C Av8 highboy (flattie v8 mill), & also for a 32 Ford 5w cpe w/an early Old v8 for me.

    Not hard, just takes a bit of time. Good luck. Do make sure the Ackerman is correct - it'll make like easier. I'd also suggest a panhard bar, & good shocks. Oddly enough, partially worn tube shocks have about the right amount of "jounce" w/o being harsh. I'm sure you know how to find the correct length(s). IIRC, acvw front shocks aren't too far off if new ones are wanted. Or aftermarket works too.
    FWW.
    Marcus...

    BTW: 31Vic is correct. You've got way too much spring-pac in the rear. Start by pulling some leaves like I mentioned for the front to soften the ride, or get softer spring, & either get the springpack rearched, or reconfigure the rear crossmember to drop down further, &/or lower the frame a bit. The rather tall spacer twixt the springpac & crossmember isn't helping stability any.
    The OEM springs were a bit stiff for the lousy roads back then, even though they didn't carry much load. You've got even less on the tail of your truck now. I'd like to see the panhard bar longer, but at least level when truck is sitting at "ready-to-go" stance. Don't forget, the small block up front probably weighs less than the oem mill in originally.

    Edit: The more I look at the rear frame n axle locators, the less I like that aspect of it. It does have the look of a past 'rodent-stick'. LnL, take a small bit of time & drive or haul it to 31Vic. At the min, he'll tell you what you need to do, at best, it'll be done quickly, correctly, & safely. & you'll be a whole lot happier.
    Marcus...
     
    Last edited: Mar 25, 2017
  17. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    At least back there he has a panhard bar, even if it is about 15" above where it should be.
     
  18. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

  19. You should not be this far along in your build without a grasp on that concept.
    Doing so explains the pics and your complaint of harsh ride.
    I think you'll have some re engineering to do to get it right.

    There's 3 ways to mount the spring.
    With a spreader as shown
    With a large clamp, a bar and whirligig thinks to keep the clamp foot from walking
    Build the spring one leaf at time after you install the main leaf using a long bolt.
    If you've never disassembled or reassembled a spring like that before be sure to get directions.
     
  20. Do you see me trying ?
    I didn't get a location
     
  21. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    I mean take is rig and FIX IT! Poor kid's gonna get hurt.
     
  22. All he's gotta do is Bring it here. That's what we do.
    I have a spot at the moment
     
  23. gimpyshotrods
    Joined: May 20, 2009
    Posts: 16,249

    gimpyshotrods
    Member

    If I were close, I'd be there too.
     
  24. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    I didn't build this thing. Suspension and frame were there when I got it. I'm trying to make everything correct. I tackled brakes, steering, and drivetrain last year. Now I'm onto suspension. Which apparently is proving to be not great.

    So yes, I have a lot to learn, as I've mentioned. And that's why I'm here.

    I think all issues / options have been covered on the front. As for the rear. What do we got going on there? The shackles on the rear aren't as low as they look in that pic. They're low, but above the scrub line. What other issues are there (bracing myself)....


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  25. You have virtually no weight on the rear end of that thing... you're going to have to address all of the concerns voiced by the others, and get a spring that will work with very little sprung weight.
     
  26. Are there any side shots of the truck?

    From the rear view above it looks like the rear radius rods are below the scrub line as well.
    That 90* dog leg in them has got to go
     
  27. Low-N-Loud
    Joined: Aug 13, 2015
    Posts: 61

    Low-N-Loud

    Rears are below the scrub line. Just measured. Fronts, I'll have to jack it up so I can really get In there, but it appears that they are above the scrub line. Very close but slightly above.

    Definitely not trying to bandaide this but I've been wanting to go with bigger wheels. Would that theoretically extend the scrub line? So the wheels now are 16s. If I went 18s that wouldn't that cause the shackles to be well above? I feel stupid just asking but it's been a long day and I'm not in a good place with this truck now, so the brain is on autopilot.

    As for the dog leg issue, what sort of issues could that cause?

    Thanks man.


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  28. Happydaze
    Joined: Aug 21, 2009
    Posts: 816

    Happydaze
    ALLIANCE MEMBER

    [QUOTE="Low-N-Loud, post: 11974370, member: 271278 Would that theoretically extend the scrub line? [/QUOTE]

    No, not theoretically, but actually(!), but only by an inch - which may be enough, I dunno. All things being equal (principally sidewall height) this change would increase the rake of your truck which in turn will take away some caster, which might be an issue. But if you had taller sidewalls on your bigger wheels the effect on the caster would be even greater. A real tail chase!

    Looks very much to me as if the original builder has overdone the kick up and utilised too heavy a capacity spring and then been tail chasing and compromising (eg huge spacer and funky kink) to try to compensate, and in doing so has given you a ton of problems. Radical surgery required - not what you want to hear but possibly inevitable? But probably not as drastic as you might think and probably easiest in the long run and with an overall better outcome?

    Making corrections to over length and excess rated springs will probably get you to a decent ride but you'll be left with ride height and possibly scrub line issues, as you realise. Sometimes 2 or more steps back is the only way!

    Chris
     
  29. From the one picture, it looks quite unorthodox to say the least.
    Those rear bars need to hold the rotational forces of acceleration and braking.
    I can see why they are the way it is, but that doesn't make it ok without a better look.

    The entire frame may be a scrub line issue too.
     
    Last edited: Mar 25, 2017
  30. L N L what is your location?
     

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