Is a panhard bar appropriate for an elliptically suspended solid rear axel? - Hot Rod Forum : Hotrodders Bulletin Board
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Old 12-10-2003, 03:38 PM
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Is a panhard bar appropriate for an elliptically suspended solid rear axel?

I have a 37 Plymouth set up with a chevy drive train and the rear end is attached to original leaf springs. The leafs are 1.75" wide and have 5 leafs. I have noticed that I am getting some tire rub on the inner (body side) fender well. I suspect the springs are deflecting sideways as I go around a corner or take a turn on the highway. The rear axel is out of a '70 Camero and it does not have a mount point for a panhard bar. I was told that will cure the rubbing problem. I have also heard that panhard bars can screw up handling if the geometry is not right on. Any suggestions, comments, ideas?
Thanks for the replies.

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Old 12-10-2003, 05:22 PM
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Better shocks and a rear sway bar will solve your problem. A panhard bar will not work correctly with your rear suspension.
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Old 12-10-2003, 08:34 PM
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You say a pannard will not work. Why?
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Old 12-11-2003, 01:02 AM
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Your rear axle is located by the springs and will not move left to right. A Panhard rod is used to locate a rear end on coil springs
and using trailing arms.Maybe the springs have weakened or the tires are to wide.
As suggested a good sway bar and shocks should do it.
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Old 12-11-2003, 07:14 AM
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Not only will a panard bar not work for you it will also cause a bind. 2 ways to fix....smaller tires/or diff offset wheels....cut the body and give it some more clearance. Dont use wheel spacers. If you suspect the springs are moving check and or rebuild the front spring bushings and rear shackles. The springs are not moving but the bushings could be.......
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Old 12-11-2003, 12:30 PM
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Well, I don't agree. I think a panhard bar will work. If the bar is located above the housing there is no way there can be any binding. It will just hold the housing from moving fom side to side. Leaf springs do move a little and if you have very little clearance at your tires they could rub...Use heim joints so any flex of your springs and moving your pinion angle will not be a problem............GlennK
P.S If you are using ladder bars there is no problem at all with the pinion angle changing ......GK
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Old 12-11-2003, 10:02 PM
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A pan hard bar will pivot around the frame mounting point in a slight circle so it will cause the leafs to bind at full travel or shorter. IF the pan bar is attached to the frame rail and is 42" inches long, it will move move the axel mounting point 1" at 6" of travel.
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Old 12-12-2003, 07:08 AM
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Johnson is correct and the shorter the bar the worse it will be. Stvblt you can not run a panard bar on a leaf spring car pure and simple. Draw it out and you will see. The panard bar moves in and arc and will bind the springs up at there mounting place. Also your thought of mounting the bar up high makes no diff in the bind. However if you do use a panard bar on a 3 link or other suspension the panard bar height is what sets the roll center and in racing we play with it for side bite.

Last edited by Phat; 12-12-2003 at 07:13 AM.
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Old 12-12-2003, 08:55 PM
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Well then build a watts link. there will be no arc movement at all. ......GlennK
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Old 12-13-2003, 06:53 AM
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Kinda tuff to do as the center pivot really needs to be around the center of the pumpkin on a street car.Unless you have and underslung frame they are tuff to use. But A+ for thinking of other ways How about a jaccobs ladder? All kiding aside if the sprinds are moving it will be the perches not the springs. Some good thoughts.
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Old 12-15-2003, 10:30 AM
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Thanks to all for a lively discussion. Based on the discussion, I guess the panhard bar idea is not a good solution. I suppose the panhard bar works with coils because the coils have an inherant side motion that will not result in binding.

I have a follow up question. The spring shackles are a "C" shape bent bar. If I replace these shackles with a set of steel bars and thru bolts, will that reduce the side sway problem?

What if I replaced some of the leaves of the spring with thicker leaves that are 1.75" wide or wider leaves mated to the longest original leaf?
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Old 12-15-2003, 03:50 PM
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Quote:
I have a follow up question. The spring shackles are a "C" shape bent bar. If I replace these shackles with a set of steel bars and thru bolts, will that reduce the side sway problem?
If those C-shackles are what I remember seeing before, yes- by all means replacing them with flat steel will help support both sides of the spring.

Those C-shackles should be replaced, and along with them the spring bushings, even with just plain rubber replacements.

This can be the majority of your problem with the rear suspension.
Just to be sure, try jacking up one side of the rear and watching what the whole rear suspension system is doing.

I am willing to bet you will find quite a bit more side-to-side movement that you want, and you may also see the leaves twisting on those C-shackles much more than you will find than if both sides of the spring were supported.

Let us know what you find out if you try this.
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Old 12-17-2003, 11:14 AM
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I have removed the rear axel and broke down the spring shackles and spring pivot mounts. You are right M&M, the fit is sloppy and the bushings are worn and dried out. I am going to replace the shackles with new bar steel and thru bolts and new bushings. That is a lot cheaper than new springs and should make the car handle better. Thanks for the advice.

Last edited by jpd37; 12-19-2003 at 10:05 AM.
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