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4, 3, 2 link suspension?

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What are the pros/cons of a 4, 3, 2 link control arm setup?


Pics for clarity. 4 link being what the MJ has stock.





What I'm calling a "two" link as there are only two points of connection to the frame.






3 link









I would assume the "two" link would be preferred for offroading as it has the fewest points of articulation which means easier fabrication and less chance of suspension binding as it cycles and greatest potential for suspension travel.


Maybe not as "safe" since there are only two points of connection. If one fails you are in a serious world of sh*t, especially if you are traveling at any speed.




I would imagine a four link suspension offers the greatest on-road manners and keeps the vehicle more planted, but would it really matter for the typical nonashole MJ driver?

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Whooo boy.  That's a BIG topic.  Something you might be better digging around the pirate4x4 forums for.


I'll give it a try, but I'm sure I'll miss a LOT of the nuances, so consider the below some pretty broad strokes.


First picture above: What I assume you are calling "2-link" is what most people call "radius arms" and it's major pros are:

- Simplicity (and usually inexpensive as a result)

- 4 points on the axle, keeping it from rotating.

- Doesn't bind


Cons are:

- All the load goes to two points on your vehicle.  If either of those fail, you're in a REALLY bad spot. (you're usually ok for a bit if one of the short arms fail)

- Has the most propensity to "unload" on steep hillclimbs (for better understanding on this topic, again...pirate4x4 forums and search for topics about anti-squat and anti-dive)

- Your axle rotates in the arc of travel, which may put added strain on your driveshaft u-joints.


Second picture above: This is usually called three link (some people get nitpicky about the drag link and call it a 4 link and the stock suspension a 5 link):

- Simpler than a 4 link

- Has one more point to the body to spread the suspension load compared to radius arms

- Doesn't bind

- Axle doesn't rotate in the arc of travel (if setup correctly)


Cons are:

- Still fewer points on the body than a 4 link.

- Single point of failure in the upper control arm.  If that thing lets go, you're likely to end up in a bad place as your axle will rotate freely, wrecking your steering and, potentially the axle itself.  This is something that should be made to be stronger than all the rest of the suspension components as a result.

- Requires more thought in where each link is mounted in relation to each other to control how the suspension articulates.


Lastly, the 4 link...which is the basis for our stock suspension.


- More redundancy.  Losing a link in this style isn't usually as catastrophic as the other styles.

- You have 4 points of connection between the body and the axle both, spreading the suspension load across more area.

- You CAN set it up with triangulation and eliminate the drag link (which controls axle movement side-to-side).  This is more commonly done on the rear as doing it on the front is hard with space constraints and requires hydro steering, unless you like bump steer.

- Axle doesn't rotate in the arc of travel (if setup correctly)

- Most similar to the stock jeep design.


Cons are:

- It WILL bind.  That isn't necessarily a bad thing and, if setup properly, when it binds may be well beyond where you care anyways.  However, this takes a lot more thought than the other two options listed above.

- More complex, which means it's harder to get it just right (often due to compromises having to be made for other desires...such as not cutting up the body/floorpan, or not having a mounting point hanging way down below the frame rails).

- Harder to package...there's a lot of stuff in the front of a vehicle.



There's definitely a lot more that could be covered, and there may be minor inaccuracies, but I think the above covers the biggest points from my own reading online.  

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Codemonk nailed it.  


Radius arm (the first one) is at least these days on the lesser desirable side.  


3 link is a great set up and really the biggest difference between the choice to go 3 vs 4 link is packaging. Easier to place 3 links than 4. 


End of the day each system is better suited for what type of wheeling you want to do. 

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