Fabbing a new 4 link....HELP!!!

Well I just got the new plasma cutter, link ends, link tabs, and all my steel stock so I guess there's nothing left to do but start fabbing. My plan is to build a triangular 4 link with my bags on the lower bars. The truck is a crew cab square with a 4.75" SFBD. My questions are what angles do my upper bars need to be from the axle?? I've heard everything from 25* to 45* so any help on that would be great. Also do my upper bars need to be as long as my lowers?? I've gotten a lot of different answers on that also. This is the first time I've ever built my own link setup so please someone explain this. Thanks guys.

The angle on the top bars should be as much as possible, you wont get 45 deg without really short bars which arent good either. The longer the bars the less axle wrap you will get and the pinion axle wont change as much throughout travel. They dont necessarily need to be as long as the bottoms. Also the more angle you get them the less chance of sideways movement. Not enough angle and you will get sideways movement. There is a happy medium between length and angle, but you also have to consider obstructions such as gas tank etc. One more thing to consider, the upper and lower bars need to be parallel. That is my short version, there are more specifics but would get real confusing. There are things like pinion angles being almost equal (not exactly) but opposite. I would say 90% of the trucks people build their own link kits for are done technically wrong but are close enough and most probably dont have issues but I have seen a bunch over the years that just down right scared me.

Getting real specific is usually done on race cars be it drags, circle track, or whatever when things need to be set up very accurately.

A few years ago I posted up a very well written article from air ride technologies on how to set up a four link correctly. You may find it by searching.

Hope I didnt confused the hell out of you, but there is more to it than just cutting up some pipe and welding on some tabs. If not done at least somewhat right it can give you bad vibrations from your drive shaft, bad wear on u joints and could be unsafe.

Awesome post man...great pointers

Thanks Krewzlo!!
I've set up a few 4 links over the years just never fabbed my own from steel and end links. I've always bought bolt up kits or at least kits with prefabbed bars. So trying to figure out all the angles and bars lengths and what not can be tricky. I'll never learn unless I tear in and start chopping and welding though. Thanks for all the info and I'll post some pics on my build page.
I almost for to ask also should I build a triangular 4 link or should I go with a wishbone for an upper link?? Is there really an advantage or disadvantage to a wishbone or is it just going to do the same thing as the upper bars of the 4 link??

Here is a decent article on 4 links



Another with some good info, remember though these are for hot rods that dont utilize as much vertical travel we do. Their bats are much shorter and wont work as good as longer ones at less of a triangulated angle.