A general 4 link/3 link question...

[pontiacgp]

that looks like an interesting set up but with that wishbone there would be a major bind going around a corner. The rear end would be trying to lift one side and lower the other side of the wishbone. Who ever designed that need a self aligning bearing in the ear of the rear end to prevent binding. I imagine that set up was in a show vehicle?

 

[kornball426]

It's a pretty common setup... They usually use a so called "johnny joint" or a heim joint at the top to allow articulation. Although the one in that picture does appear to just have a bushing in it. I'm guessing it's for show since it's bagged and has no bed floor, I think it's a Toyota of some kind... I just googled wishbone three link and picked the nicest looking one on the first page. :lol:

I've see a lot of those on trucks though... And Jegs and Summit sell them in the chassis section with the four link and ladder bar parts with the claim "the most accurate way to center your axle".

This one looks nicer, though it's not installed... but it has heim joints instead of bushings.

 

[pontiacgp]

I googled the wishbone 3rd link and only found it used on trucks with bags....which is not my bag.

 

[kornball426]

Yeah bagged trucks are not "my bag" either... But it's also pretty popular on rock crawlers and some drag cars too.

I first saw it on a rock crawler which is what got me interested, plus the ones I've seen on drag cars I like if used instead of a triangulated 4 link, because I don't like the panhard design needed with the all parallel bar four link design. I think it's a dumb way to keep an axle in place, why would you do that and have your axle move side to side through the suspensions' range of motion when a wishbone or watts link will keep it centered with little if any side to side movement in the suspensions travel. I guess for circle track the panhard can have an advantage since it can be adjusted to put more or less load on the rear tires from side to side... But for a street vehicle or road race style vehicle that makes turns both ways I think it's a lame design. It works, it's on millions of cars and trucks but from an aesthetic point of view, and design point of view I just don't like it very much.

 

[pontiacgp]

there is a formula to figure out what the horizontal movement of the body with a panhard bar...and panhard bars longer than 3 feet fit on a G body

s = r - (r2 - l2)0.5

In geometric terms, "s" is called the "sagitta" of the arc. As you can see in the illustration, the sagitta's length is equal to the forced side-to-side motion that's induced on a bump. Of course the dimension "r" equals the radius of an arc, and in the illustration r is equal to the length of the Panhard rod. The amount of vertical movement = "l". (Technically, "l" equals one half of the length of a "chord".)

When subjected to a three-inch tall bump in the road, a 12" long Panhard rod would subject the car to a horizontal body movement of 0.381", which is enough that most drivers would perceive it as a noticeable "shimmy" or, in other words, as a "bump steer" effect initiated from the rear of the car. By comparison, a 36" long Panhard rod in the same situation would subject the car to a horizontal body movement of 0.125". That's unperceptible to most drivers.

 

[larryo454]

Hi i like the idea of the watts link it has little or no bind

http://www.youtube.com/watch?v=-J4xkHuP7QY

 

[kornball426]

Yeah watts links are really cool... You don't see very many of them though, I think because they're so much more complicated than a panhard bar.