Alright, back to work. You might remember we left off with a sectioned frame and a big aluminum swingarm, looking like so:
The loop I designed came in. I talked to the tubing bender and modified the design slightly to eliminate the 'S' curve portion. I didn’t take a lot of pictures of the install, but this should show you how it worked out.
I lopped off the original shock mounts and seat support sections. I birdmouthed the ends of the frame rails that were left. The old seat support plate was split, and the top rails heated and spread to the wider width I wanted for tire and fender clearance.
You can see in this rear view how wide the gap in that plate is currently. That started as just a .040 wide gap left from the cutoff wheel.
I chopped an axle I had leftover from the SV650 swing arm into 5" slugs, and used it to join the new loop to the old frame at the diagonal sections
Sharp eyes will notice that in the last two pics, the old swingarm is back in place. I decided to give it a shot instead, though I do have the monoshock from sv650 on it’s way and may toy with that idea more before all is said and done.
That being said, we can’t do a whole lot with this short and narrow stock swing arm. So let’s make it longer, shall we?
I started out using painters tape to give me a guide for cutting, as well as have some witness marks to make sure the axle plates got back in place straight.
Before I cut them, I remembered to indicate right and left as well
The swingarm is roughly 1.25 OD and surprisingly was only .0625 wall. This gave an ID of about 1.12”. I hit the local Alro Metals Plus and picked up a chunk of 1.125” OD tubing with .188” wall. Math guys will notice that the OD of the DOM is larger than the ID of the swingarm. That’s ok. We like interference fit here. The fun part will be fitting the pieces together.
This starts out with creating a tapered lead on the tubing. A couple quick spins on the bench grinder and it looks like it should work (fingers crossed).
After a few smacks of the ball peen hammer, the DOM slides inside the axle plate end of the swingarm tubing about an inch before bottoming out
At that point I repeated the process, tapering the other end of the tubing and driving that side of the swingarm in place. I clamped the whole thing in the bench vise, and since I wanted a 3” extension, I marked 4” on the tubing from the end of the cut swingarm, allowing for an inch to be slid into the remaining swingarm half.
Once they were cut, it was a simple matter of tapering the exposed cut ends of the tubing, aligning them using the witness marks from earlier, and driving them together until I reached the desired 3” dimension.
Before welding, I wanted to be sure the legs weren’t going to move on me radially, longitudinally, or laterally. So using a piece of 5/8” all thread, a handful of nuts and washers, I secured the assembly good and tight.
A few welds later, and we have a very solidly extended swingarm.
I will clean up the welds with the power file, and then when it comes time for final frame finishing I will fill the lower areas with reinforced body filler. Before that though, it will get a brace ahead of the tire that will also serve to mount the front of the fender, plus it will get better shock mounts.
In the meantime, I did a little work with the welder and flap wheel shaping the rear of the gas tank a little better. It’s far from perfect, but another hour or so and it should be ready for stripping the paint, body work and prep.
By the way… I sold the ape hanger bars on eBay. So we’re looking for ideas. I picked up a set of these in a trade for other old parts we don’t need. I think they might look good on there.
