Thread: 4 link or ladder?

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Jack, let me see if I can unshroud this Panhard bar thing for you. It is unclear whether René Panhard or Émile Levassor or one of their hired engineers came up with the Panhard bar, but I'm pretty sure that whomever came up with it, they installed the bar with the longest possible length to fit into the car and also installed it parallel with the road surface to prevent pre-loading one side of the car or the other from the neutral ride height position.
http://www.citroenet.org.uk/panhard-...anhard-01.html

Now, along comes some of us goofy hot-rodders and the Panhard bar looks like a good, cheap, easy way to prevent lateral body movement in relation to the differential housing and it is. Problem arises when the builder fails to take into consideration that the bar must be as long as possible to keep the degree of angularity as low as possible and prevent jerking the body laterally on bump and rebound.

Proper bar construction and installation would dictate that mounts would be constructed to attach to the frame and to the housing that would allow the attachment ends of the bar to be right at the brake backing plates on each side of the car, thus allowing the longest possible bar length within the space available. The bar doesn't necessarily have to be straight, it can be curved or bent up like a pretzel, so long as the attachment points are as far as possible apart from each other and each attachment points are parallel with the road surface and the material used is stiff enough to resist deflection. That's where the Panhard bar gets its bad name, when shadetree engineers make the bar short because it is easy and expedient to do so. In my experience on this rock, I have figured out that if anything can be FUBAR'd, human beings can and will do it.

Bottom line: A properly engineered and installed Panhard bar will do a fine job of locating the differential laterally to the body. Not as precisely as a Watt's Link, but good enough. The key is the length of the bar and having both attachment points parallel with the track surface at ride height.

Here's a hastily-drawn diagram carried out to the point of silliness to illustrate my meaning......