I get tired of hearing and using the same old cliches. "It is what it is". This usually refers to a situation that cannot be changed or something unacceptable that we accept based on it's onerous nature. There is usually another side to the matter that may offer some equtiable solution if we are only willing to look. From now on my new cliche will be "It isn't what it isn't".
One of the problems you will run into when building a project is not having the right size material to make a part. It just isn't what it isn't. Often times you just have to use what you have at hand. For example the next part we need is a good solid pick up point to connect the rear trailing arms to. These mounts will need to be strong so I will be using some 1/4" thick angle iron. I need a piece of angle iron that has one leg about 1 1/2" long and the other leg about 4" long. All I have is 1 1/2" angle iron. But wait, I also have some 1/4" x 3" strip. If you have enough welding wire you can usually make just about anything work. Just grind a small bevel on the edges and slide the 2 pieces together. Be sure to tack both the front and back sides first so that it will not warp when finish welding. You want them to be nice and flat. This is where the angle grinder with a flap sanding disc really works well to grind the excess weld bead off. We will be using 1/2" bolts to connect the arms to the mounts.

Do you suppose that the welded spot may not be strong enough to stay together with the constant flexing of the rear swing arms? Well just to be sure we will install a couple of gussets to reinforce it. Gussets are nothing more than a piece of support to tie two pieces together so they cannot flex.

Gussets do not have to be anything fancy but they need to be flat in order to get the best weld possible. These strips of 3/16" thick should do the trick.

Magnets work well in holding the gussets in place while they are tacked on.

We need some nylon bushings for a bearing surface for the 1/2" bolts that the swing arms will pivot on.

The nylon bushings are sized so they fit snugly into the bearing housings. I will need to drill and tap some holes in the bearing housings for a grease fitting. You will notice that the housings are about 2" long while each of the bearings are only 3/4" long. This will leave a little gap in the housing for the grease. It is easy to forget little things like this once the project is nearly completed. It is a good idea to make a list of things to remember to do and keep it with your notes on the project for reference. I will do that right now.

Now we can bolt the swing arms onto the pick ups. Always use grade 5 nuts and bolts. Fine threads are preferable. Remember to put a metal back up washer on each side of the nylon bearings. It is best practice to use nylock nuts on the final assembly of any bolted component. A nylock nut is symply a nut with some nylon in the end that creates surface tension between the nut and the bolt thread in order to keep the nut from loosening up. In a somewhat crude bearing application like this you only want to tighten the nuts enough to make them snug so that the arm can move freely. You will notice that I have not used nylock nuts for the initial fit up. That is because regular nuts are much faster to assymble and disassymble. I hate to tell you this but we will have to take the entire cart apart for finish welding, sand blasting and painting. Nylock nuts cost more but they are well worth the money. Besides you can use the regular nuts over and over again anywhere they are needed.

Just as a side note, have you ever noticed that screws always rattle loose. Why can't they also rattle tight. Imagine you are riding along in your car and you say to your buddy , hey do you hear that sound in the dash? Yeah what is that? I think it's a tight screw. Just remember "it isn't what it isn't."

The next photo shows the basic components of the rear swing arms. We will now have to figure out exactly where to place it. Since I know where it is located from the CAD drawing it is just a matter of measuring to the centerline of the axle. What axle you might ask.

We will now use a piece of 1" tube to act as our axle in order to line everything up. The next photo illustrates the parts we are working with. The swing arm assymbly needs to be perpindicular to the center line of the cart. It is never a good thing to have the front end trying to go one way and the rear end go another. This can be observed in a vehicle with a bent frame. From behind it looks like the car is going down the road sideways. Also hard on the tires. You can't see it very well but in the center in between the swing arm mounts there is another set of Azusa bearings that are installed on the axle tube so that they can be perfectly lined with the outside bearings. The sprocket will be mounted to this set of bearings. We will be using a 1" axle with 1/4" keyway for the final drive system. You may ask why not just use the actual solid 1" axle we will eventually need to line it up. Shut up!! No this is a good question. We are not using a solid axle design so we can get by with a shorter length of axle for the completed drive system. Hopefully we will save a little money by purchasing a shorter lenth of solid axle. Besides, I have the 1" tube on hand and we will use it for other things as well.

Oh and by the way, don't forget to turn the frame over so you can install this assymbly on the underside of the cart. Of course you can do whatever you like. I usually do. In this next photo the frame is turned over and we will try to line it all up staight and perpindicular before tacking it on.