This morning I made my swingarm shaft spacer. Starting with 7/8″ OD .156 DOM, I cut it to length with a hacksaw, filed the ends a bit to ensure that the faces were perpendicular, then reamed out the ID to fit over the unturned (14mm dia.) portion of the shaft.
Using the reamer required a lot of “feel.” Unlike when I reamed the the frame plate, which was only about 1/4″ thick, this hole was 36mm deep, which presented a lot more surface area for those blades to bite. At first it was either not taking off much metal or binding up. Just about the time I thought I was going to have to give up and devise some other method, I suddenly got the feel for how much pressure to put on it and started smoothly making a bunch of shavings. Before long, the shaft slid in perfectly.
Once done, I put it all together and torqued the bolt tight. OH NO! The swingarm was suddenly extremely stiff. What had I done wrong? Where was it binding? I carefully looked everything over as I disassembled it. As it turns out, the stiffness was not the result of binding side to side. It didn’t even have anything to do with my design or workmanship; the stiffness was between the plastic swingarm bushings and inner race (both stock parts for the Yamaha swingarm I’d bought brand new). It turns out that they are just a very snug fit initially, This was only evident once I torqued the bolt down enough to stop the inner race from rotating on the pivot shaft. I coated the race with some Bel-Ray assembly lube and put it back together. Moving the swingarm up and down a few times started loosening things up.
The whole process took me about two hours.
I’ve said this before, but getting through all these little steps is the whole point of this project. I am NOT trying to come up with a super-cool, super-cheap, or super-functional motorcycle to ride. I’ve got three bikes in my garage already, and they will all always be superior to this one in just about every way. But I am learning a thousand little things through experience, which is exciting to me. I didn’t grow up with a gearhead dad or uncles or neighbors, so I’d never tapped threads or used a reamer before this. It’s cliché to say, but in this case the journey truly is the destination.
