Let's play name that tune. Sometimes I am reminded of a song when I make a statement. I wonder if subconsciously the song actually influences the words I use. When I make a statement that reminds me of a song I will put the actual phrase from that song in parenthesis with the letters (NTT) which of course stands for Name That Tune.
You can start at any point you like ( NTT "You can check out any time you like") in the construction of the front suspension but like the two sets of workers building the railroad track from opposite ends, you want to make sure the ends are going to meet up in perfect alignment. If we plan on having wheels on this cart then we will need a way to connect them to the suspension. One way is to use a common bolt that is matched to a set of bearings in a wheel hub. I have chosen a wheel hub that has a set of 3/4" bearings so it will require a 3/4" grade 5 bolt. There are different grades of nuts and bolts. You have your standard everyday commercial grade that is found in any hardware store. This is fine for bolting two parts together like a gate latch or lightweight use items like a mailbox or wheelbarrow. But for something like a go cart that will see constant twisting and shearing forces you need to step it up to grade 5 or grade 8. Grade 5 will be fine for this project because some of the hardware will be welded to other components as we will see next. Grade 8 has a higher carbon content and would be subject to cracking under stress after being welded, or at least after my welding. Grade 5 hardware is identified with opposing marks on the head of the bolt. Otherwise they all look pretty much the same except grade 8 has a more yellowish tint. Anyway you have to start somewhere and it is sort of like the ankle bone is connected to the shin bone ( NTT) and so on.
The spindle that holds the wheel consists of a 3/4" bolt welded to 2 pieces of 1" schedule 40 pipe that serve as pivot points for the steering. You begin by welding the 2 pieces of pipe side by side making sure they are parallel to each other.

Next step is to weld the nuts to the ends of the pipe. These nuts will receive the Flexible Rose Joints that will allow the steering to turn smoothly on its individual axis. You must weld these nuts in short steps in order to keep from distorting them with too much heat. Just take your time here. It will pay off in the long run. Just keep using short spot welds alternating to opposite sides all the way around. Let the parts cool down between welds. Go do something else. Go take the trash out. Sweep the floor. Write your wife or girlfriend a love song. I will be using a 1/2" nut on the top and a 5/8" nut on the bottom. We use a larger size on the bottom because of the greater stresses exerted on the bottom joint. The easiest way to get these nuts on straight is to first screw a bolt on to the nut then insert the bolt inside of the pipe. Use of a clamp will hold the nut firmly in place while it is welded to the pipe. Also the welding ground cable can more easily be connected to the work piece. This is where a metal work table would really come in handy. You would just need to ground the table instead of trying to figure where to connect the ground to a small work piece. In this picture the 1/2" nut has already been welded to the other side. This is the 5/8" nut end ready to be welded.

This is the 5/8" Nut end steadied on the side of the table and ready to weld.

Both ends now have the nuts welded to them. The spindle bolt can now be welded on taking care to get it paralell and perpindicular to the pivot nuts.

As you can see my welding has a long way to go. As I see it you can have pretty and you can have functional. You can have pretty without functionality and you can have functional without pretty. The goal of course is to have both. For now I will settle for functional because no one really cares how good you look if the wheels fall off.

This spindle looks very lonely to me. I think it needs a steering arm for a partner.