 Once you have all this figured...  Once you have all this figured out, it's time to start on the truck. Begin by building your axle bridge to mount the upper links to the axle and the lower link's axle mounts as well. Remember to set your pinion angle first, depending on whether you will be running a CV or U-joint, and then only tack-weld everything. If you need to change it, this will make moving parts that much easier. |  Next, build the bracket to...  Next, build the bracket to attach the lower links to the frame. You may want to build a crossmember for this if you determined that you need it to get a better roll axis. These brackets may also become skid points when you encounter obstacles, so you might want to build their forward edge with an angle to help slide over things. |  Just be sure to use the proper...  Just be sure to use the proper materials we discussed last month, as there is a fair bit of force put on all of these points. Plus, if you are not a skilled welder, or this is your first welding project, stop right now. The welds on these components must be very good; if they fail, it can be fatal. |
When you get to the upper link's frame mount, we recommend using a bracket that has multiple holes drilled for attaching the upper links such as this one from A&A Manufacturing. Attach this bracket so you can move the upper link's frame mounts up and down from the ground. This will be your initial point of adjustment to fine-tune the suspension whether you are going racing or rockcrawling.
Now that you have everything in place, it is time to cycle the suspension. Notice if the axle moves straight up and down as it should or if it swings forward as it articulates, as it shouldn't. Are the links and rod ends binding? If so, do the brackets need to be angled to follow the line of the links? Plus, what about everything under the truck--exhaust, fuel tank, spare tire, and so on? Is there clearance for these or do they need to be moved? If everything seems to be right, it's time to burn in the welds. Just remember that it is not uncommon to need to tear into the suspension again to get it to work a bit better. Do not be surprised if you are adjusting things three or four times before you get it how you like it. You may still want to change more, depending on the terrain you encounter or the driving style you prefer. This is only one way to build a four-link, and different builders will try different methods. If you enjoy a challenge and are willing to spend the time, money, and energy to fine-tune your suspension, then a four-link may be right for you. If not, then stick to a professional kit, or leaf springs, and just go have fun on the trail.
Four-Link Suspension Tech - Part 1