Proper panhard bar length and location?

I'm in the middle of setting up my suspension on the rear of my '58 Chevy truck and had the question as to if it matters where the panhard bar is mounted and how long is long enough. I understand that longer is better but since the fame on the truck is really narrow, I'm pretty limited with how long I can go. I have also contemplated on using a diagonal track bar instead of the panhard bar for this reason. Any input would help tremendously

-Thanks

 

Why not make it longer and mount it beside or part of the 4 bar bracket..

 

Do you mean something like this?

That's what I meant by a diagonal track bar. Only thing is I've read that it's not as effective as a pan hard bar. It's more of a drag racing setup.

 

No no..forget the diagonal bar as it's a mainly dragracing setup.
Mount it like you have mocked up in your 1st pic but instead of it bolting to the diff head make a bracket off the upper rear 4 bar mount.

 

A short panhard bar will allow the axle to move through an arc moving it sideways, affecting the handling. It needs to be as long as possible but as you have a narrow ch***is width a watts linkage will do a better job. It will locate the axle exactly and not allow sideways movement.

 

Yep, the longer the better.

 

That's what the consensus is going to be.

Keep in mind that the bar needn't mount to the axle centre section. It needn't be at that height, either; it needn't be perfectly square to the car's centreline; nor need it be ahead of the axle. Aesthetics aside, the simplest way would be to run the bar behind the axle, at about axle height, from a bracket on the axle somewhere near the right-hand brake to a bracket projecting leftwards out of the left-hand frame rail. That'd give a bar about three times the length of the one in the photograph.

With a Panhard bar the roll centre will be located where the bar axis intersects the central vertical plane of the vehicle. It has become customary to set up "conventional" ch***is with the rear RC a bit above the middle of the rear axle, but there is no reason it absolutely has to be that way. The Locost guys have all kinds of ways to put the RC somewhere underneath the axle, so it's quite possible. A lower rear RC would make for a bit more understeer and a bit more roll overall, something to keep in mind when selecting spring rates etc. If this is to be a working truck a lower RC would allow you a bit more spring rate at the back. Though in truth I'd say we're splitting hairs.

 

This is my approach to this question. The panard rod length will be determined by the suspension travel of the vehicle. Since you have not "c" notched the frame or spec'd the suspension yet it is impossible to determine the travel of the ch***is. After you have finished the "c" notching you need to trial run your suspension travel and determine the amount of travel you approximate and the change of position of the panard axle mount during this deviation. You might find that the mounts you have has a minimum lateral skew and can be run as is. If you have a large lateral skew then a longer rod position may be necessary and this can be achieved by simply making a new pinion bracket clocked further to the p***enger side to make the rod longer.

To determine the lateral skew fasten the panard rod to the frame, remove the bolt from the pinion mount and allow the rod to float in the mount. As you raise or lower the rear axle you can see how much the rod will shift the rear axle on the panard rod radius of operation. If the hole moves excessively then you will have to change the length of the rod and reposition the mount or mounts.

 

A watts linkage would be best in my opinion.

 

I don't have the option to mount anything additional in the back like a watts link since I'm running my air bags and shocks on the inside/rear of the frame because I need to run my exhaust through the outside of the frame. I opted to put a longer panhard bar that would mount on the bottom of diff axle housing, through the 4 link bars, to the frame. Or just K.I.S.S. and mount it on the top of the diff axle housing as far as possible to the other end of the frame. I went and bought some 1" X 3/16 wall D.O.M. tubing and left and right hand thread heim joints and taps to make the bar adjustable.

 

What about something like this

 

That's interesting. It would just be a matter of making/buying something like that, that would work with a 9". And just make sure it wont interfere with the links.

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