Step 4: Installing the Transmission Or- the RAGB
The next step is to install the RAGB ( transmission). This was a tedious task because the RAGB I chose has an unusual triangular shape and a strange bracket. Additionally, the RAGB shaft has to be far enough off the ground, yet not too far up as to protrude above the diamond plate covering it. When all the measurements were done. I had 1/4" between the top of the RAGB and the cover. The RAGB sits on two cross members welded in the frame. If you look at the pic called: "Battery bracket", you can see how it is configured. In the next pic you can see the RAGB bolted into place.
Before we get any further, you'll need to determine what your gearing ratio will be. The RAGB is a 2:1 ratio, meaning that two turns go in, one comes out of the output shaft. I suck at math, but my gear setup is as follows: Centrifugal clutch is 14 tooth. Input on RAGB is a 14 tooth. Output on the RAGB is 12 tooth, and the rear axle sprocket is a 40 tooth. That worked out well, but I have no clue what the final ratio is. The engine speed is around 4,500-5,000 RPM.
I'm using an all chain drive system. Many use belts, but I like the idea of using a chain. I used #35 chain for this build, but many use #40.
The next step is to install chain tensioners. The chain needs to be somewhat taut, but not tight. All chains will loosen and 'stretch' with use. So you need to have tensioners to keep that tension at the right level. The RAGB to rear axle tensioner was a problem because there was very little space to install one. My solution was to install a skateboard wheel that slides up and down in a 1x1 piece of steel with a slot milled along it's length. This enables you to slide the skateboard wheel up and down against the chain. You wouldn't think skateboard wheels would hold up, but they work great. Seeing as how they are designed to handle a person riding on asphalt, chain doesn't cause any damage to them at all. In this setup, I just have enough room to get into the area with a wrench to loosen/tighten the tensioner.