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Panhard with leaf springs?

Discussion in 'Center Of Gravity' started by sled_dog, Feb 28, 2005.

  1. sled_dog

    sled_dog 1 ton status

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    I don't think I've ever seen this discussed here. What would you guys say about installing a panhard with my leaf sprung front? I've heard from the street crowd its a very good thing to do on the IFS-SFA swap. I may be picking up a 90 Chevy 1500(sister wants my S10 project to drive daily), and if I do its going to get 52" springs up front and coil with 4 link out back. Eventually I plan to coilover the front suspension just not enough money right now. But would there really be anything wrong with installing the panhard now?(well not for a few months when I build it but you get what I mean). I know I've seen panhards with leaf springs(Super Duties), I don't see any real issue. Maybe a little more stress on the bushings but its not like they don't already go through hell with all that flex. Anyone done this or have experience in some way? I know the idea of keeping the panhard parellel to my drag link, I was also thinking that the tower I would need to build to mount it to the axle would be a great place to mount my hydro ram for my assist.
     
  2. RustBuket

    RustBuket 1/2 ton status

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    I think a panhard rod with leafsprings would have a really negative effect on the suspension. The springs are designed to hold the axle in place laterally so why put in something that is going to force it into another path putting stress on the frame, bushings, etc. I would think it would be totally unnecessary but I could be wrong.
     
  3. BigOrange90Jimmy

    BigOrange90Jimmy 1/2 ton status Premium Member

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    A well engineered panhard setup is a good thing. On the street, it helps in cornering by not allowing the axle to shift side-to-side or letting the shackles collapse sideways. It will make the truck feel more firm and the steering more responsive.

    On the trail, the well engineered panhard bar will not affect flex at all and will help on sidehill situations by not allowing the axle to shift.

    The well engineered panhard bar will be most effective when parallel (or as close as possible) to the axle when the truck is at it's static ride height.
     
    Last edited: Feb 28, 2005
  4. M-1028

    M-1028 1/2 ton status

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    Jeep YJ's have leafs all around and have panhards front and rear from the factory.
     
  5. RustBuket

    RustBuket 1/2 ton status

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    Well apparently I was wrong.... :blush:
     
  6. sled_dog

    sled_dog 1 ton status

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    maybe I will focus on looking for parts to make a nice hydro steer setup. Might not be as quick as responsive as I like but would make it easier to setup a "good" panhard as noted.
     
  7. az-k5

    az-k5 1/2 ton status

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    super dutys run them even with the heavy duty springs.
     
  8. sled_dog

    sled_dog 1 ton status

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    BTT for another question. I started looking around on Pirate as far as panhards. And I found a thread started by BadDog that was about roll axis and center. I understand your roll center will be about the height of your panhard to axle location, and that roll axis is where the imaginary line intersects the tires imaginary centerline, but what does this mean for a leaf sprung front with a panhard? I want a tall roll center on my front and rear(rear will be triangulated 4 link) but the front will be leaf sprung for the time being. I also read in that thread that the roll center and roll axis with leaf springs is where the springs mount to the frame. I basically runs through the mounts. So if thats true, then I should mount my panhard at the same height as my front spring hangers and level with them? I think thats right. That should cause the least binding right? My eventual setup will be a radius arm setup in the front or a 3 link, either way I will need this panhard, figure why not do it when the leaves go in?
     
  9. marv_springer

    marv_springer 1/2 ton status

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    Leaf springs like the axle to move pretty much straight up and down. A panhard bar will tend to make the axle follow and arc. That being said, for a limited range of motion a relatively flat panhard will get along well with a set of leaf springs - and add a lot of lateral stability in the process......

    So whats a "limited range" of motion..? Depends.... how flat it's mounted, how long it is... how much lateral movement in the spring mounts.
    [​IMG]
    This truck has a track bar installed in this photo, and yet it travels pretty good!

    I think the understanding of the "roll center" is commonly oversimplified w/ a track bar. Many times I've read it to be the intersection of the track bar and the centerline of the vehicle. I think it changes depending on the situation... Consider this image that shows "up/down" travel and "articulated" travel in comparison:
    [​IMG]
    For up/down, the roll center can be pretty much estimated in the way stated above. But for extreme twist..... this pic shows that the roll center actually "floats" along the length of the trackbar.:thinking: hmmmm.... what does this mean?.... not really sure....:dunno: but, it's something to think about.:p:

    Marv
     
  10. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I'm going to play the devil's advocate. I don't think a panhard rod has any place on a leaf sprung vehicle. The first time I saw the Superduty front I was quite shocked.

    I'd imagine they use it on the superduties to control bumpsteer or something. IMO it's hack. Leaf springs do a fine job of controlling lateral forces with the proper mounts.
     
  11. sled_dog

    sled_dog 1 ton status

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    Tim- talk to someone running a proper panhard setup on their leaves, all the ones I have in the past loved it. I don't expect to run the leaves for more than a season or half of one. Basically however long it takes for me to save the money for the coilovers.

    Marv- Thats an interesting illustration of roll center. But by your diagram(except in full on droop situation) the roll center stays at the same height, just different location. My thought was, mount the panhard outside of the frame rail on the driver side(see the Willy's on February 2005 Four Wheeler cover) and actually over the leaf spring mount pad on the passenger side. The goal of course being to maximize the length. As most of us know, longer it is less the angles change through the range of motion.
     
  12. divorced

    divorced 3/4 ton status

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    I saw a Chevy with a D60 front and leaf springs that had a panhard bar. It went from near where the steering box is to the top of the springplate on the passenger side, using the spingplate as the mounting point. The springplate was a custom made deal to connect to the panhard bar. One of the two bolt holes in the housing broke away, and the other bolt was twisted. I guess his housing is junk now? Just be cautious if you do it.
     
  13. marv_springer

    marv_springer 1/2 ton status

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    Agreed..... I think this is why moon buggies benefit from the tall trackbar mounts - thru full articulated travel the roll center stays higher than w/ practical 4 link geometry.

    Marv
     
  14. miniwally

    miniwally 1/2 ton status Premium Member

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    Lets break the function of the leaf spring down into the four basic functions.

    1. To locate the axle forward and backwards
    2. To locate the axle from side to side motion
    3. To hold the vehicle up
    4. Reduce/control axle wrap

    They don't do any one of these jobs well because they have to be an all around kinda deal. The friction of all the leafs together hurts the spring rate, yet those extra leafs are needed to help control axle wrap

    They need bushings at both ends to help soften the ride and reduce friction in the mounting points yet these bushings let the springs move some side to side, twist and in general not stay in one place very well.

    Using a well though out track bar with leaf springs works very well. Although parrallel to the axle sounds like the best choice you actually have to run the track bar at the same angle and length as your drag link to prevent bumpsteer.
     
  15. sled_dog

    sled_dog 1 ton status

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    Thus why I'm thinking about full hydro. Eliminate the drag link and I can just run a parellel panhard.
     
  16. joez

    joez 1/2 ton status

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    Panhards/ track bars, whatever you want to call it, have come on YJ's and all leaf sprung fords. Considering it makes the vehicle handle a lot better on road, cuts lateral movement down, and has no real ill-effect on travel, its not "hack" to have one. You can run softer bushings and a softer spring and still have it handle just as well if not better than with springs that dont move and hard bushings, and it will ride better.

    A properly done panhard/track bar has plenty of place on a leaf sprung vehicle, its more hack of GM or dodge to not use one that it is for Ford/Jeep to have them, especially on a 3/4 or 1 ton tow rig.
     
  17. sled_dog

    sled_dog 1 ton status

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    btt, looking for other constructive advice on this subject.
     
  18. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I don't know, I personally think that it's overdue that a Jeep Wrangler have a triangulated 4 link in the rear and end the madness with all these panhards and their inherent problems.

    Wonder if it'd just wear bushings too fast to be acceptable or something? (I'm talking about the rear here)
     
  19. joez

    joez 1/2 ton status

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    You havent done much work under a stock Tj have you, theres no room for a full triangulated 4 link from the factory. And why would that be better for a rig that 90% of people buy to leave stock and only drive on pavement?

    Besides, TJ's have nothing to do with Panhards/track bars on leaf sprung vehicles.
     
  20. BadDog

    BadDog SOL Staff Member Super Moderator Author

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    I think the effect pointed out by Marv only happens when axle roll (aka "articulation" or "flex") exceeds the ability of the suspension and springs to keep it relatively even. IOW, when the stuffed tire hits the bumps (or rate goes high), or when the drooping tire hits the strap, then the roll center/axis is going to quickly shift to the limited side. But as long as the suspension is still in "balance", it should remain relatively centered.
     

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