4-link vs. 3-link vs. everything else?

I've been looking around the forums, searched google and NAXja, but couldn't find anything on the subject. Can someone explain the difference between a 4-link, 3-link, Y arms, and any other type of suspension setup I'm missing?

Your stock XJ suspension is usually reffered to as a '5' link. You have 2 lower control arms to keep the axle in place, 2 uppers to control pinion/caster angles, and a trackbar to keep the axle centered left/right.

With a 3 link, you remove one of the upper control arms so there is less binding (and more flex). Its done with no rubber bushings (they allow too much movement), and has the trackbar still - is commonly called "3 link with panhard" . panhard = trackbar. Rock Krawler offers a popular 3 link for the XJ.

A 4 link has 2 lower arms and 2 upper arms at opposed angles, triangulated - with no trackbar. It allows for amazing flex but is tricky to setup right. Its usually only used in the rear. Go to the pictures forum and look at the buggies there - most run a 4 link rear.

Radius arms use 2 long lower control arms, with short upper control arms that go from the axle to the lower arms instead of the frame. It allows for incredible suspension travel with good angles, but causes some binding with articulation. Its a good compromise all around and a very popupar setup - look at RE's longarm kit, the TNT Y-link.

cal said:

Your stock XJ suspension is usually reffered to as a '5' link. You have 2 lower control arms to keep the axle in place, 2 uppers to control pinion/caster angles, and a trackbar to keep the axle centered left/right.

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it's referred to as a 4 link + panhard. the panhard does not count as a link

IntrepidXJ said:

it's referred to as a 4 link + panhard. the panhard does not count as a link

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I dont disagree with you, but I still hear it referred to as a 5 link more often than 4 + panhard. For whatever reason, no one seems to say that.

I've only ever heard it called a 4-link, i.e., Full Traction's kit...

then again, I have about 1/4 as many posts as you guys

I'd say nobody's really wrong since the track bar, or panhard bar, plays just as important of a role in positioning the axle, and could easily be considered a "link".

However, I usually hear it called a "4-link", with a track bar, and a "triangulated 4-link", without.

I know in racing, they only count the "parallel" links, and the track bar is.... well.... a track bar.

so if i took off one of my uppers would that do anything

xj151 said:

so if i took off one of my uppers would that do anything

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That depends on what kind of uppers you have. If you have rubber bushings involved, it would turn your jeep into a rolling deathtrap.

3 link requires hard joints or you will get a lot of axle wrap.

cal said:

That depends on what kind of uppers(and lowers) you have. If you have rubber bushings involved, it would turn your jeep into a rolling deathtrap.

3 link requires hard joints or you will get a lot of axle wrap.

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And some really good arms!

Well yes. It didnt occur to me that was necessary to say, but I guess it really was

I wouldnt do it with less than 1.5x.250" DOM, but I've seen others use heavier yet. There are a few people who run with less, but they are typically trail only rigs.

xj151 said:

so if i took off one of my uppers would that do anything

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running a 3 link also requires serious strengthening of the remaining upper link mount...

trust me - mine ripped off the frame...