A couple weeks back I got another chance to work on this fork conversion. I just never got around to putting the pics up. Things have been hectic lately.

When we left off, we were modifying the fork to work with the original Suzuki axle for this hub. The answer to the bonus question from last round? I’d bushed one fork leg but not yet bored it to allow access to the fork damper retaining screw. Bill Becker was the first to point this out, just minutes after the article was posted. If anyone has an nit-picky eye for detail (and style), it’s him.

This time I modified the axle and related hardware to finish this job.

Here we go.

I was able to mount the fork leg to the milling machine table vertically with just enough room to get the boring head setup. However, there was no way to keep the leg secure enough with it acting as such a long lever and having limited contact where mounted. I then decided to mount an extra vice we had in the welding area to the table with a large angle plate. This allowed me to hang the leg off the side of the table so it could be clamped closer to the work area.

Big old vise mounted to an even bigger angle plate. This setup worked pretty well, even if I did scar up the fork leg a bit. Nothing a little sanding and polishing won't fix.

Leg after bushing has been bored to match existing bore in axle boss. Now you can get the damper retaining screw!

There needs to be a means to secure the axle while tightening down the axle nut. I don’t want to rely on the pinch strength of the boss on the other leg as it seems lame and likely to stress the leg. It also leads to incorrect installation as the last step of securing the wheel is to tighten the pinch (after axle nut is torqued) so that the legs are parallel and not pinched together. I decide to make a small diameter hole in the axle for insertion of a screwdriver or rod to keep it from turning. Old Harley Hydraglide forks use this setup and it works. In our case there is no axle protruding so I made the hole so that it lines up with the damper retaining screw hole under the leg. Hidden. Functional. I did realize afterward that while I intended to drill the larger end, I messed up and did the smaller end. Dammit.

Axle secured in a v-block. Located under the quill using a "wiggler" for drilling.

Axle drilled. Hole is perfectly centered. Drilling on a milling machine is so much easier.

Whole setup assembled. Note the access hole for securing the axle.

I turned down the axle nut to leave room for a lock washer and made up a thick flat washer to spread the clamping force over the original fork material and the new reducing bushing I installed. The washer has a flat ground in it to engage the lower fork casting so it doesn't rotate when tightening.

That’s it for this session. I have to drop some parts off for chrome and polish the lower legs then we can assemble this and ship it home.

Jason

Managed to squeeze in one more session last night before heading out for vacation in DR Friday in the wee hours. You know I’ll be thinking about this project next to the pool with a drink in my hand. Can’t turn it off. Ever.

I walked into the shop last night at 8:30p after a 15hr day traveling and working. I was on the lathe making chips by 8:33p.

This is the original Suzuki axle that belongs to the hub/brake. Research showed that most folks used the Norton axle for this modification. Well, I don’t have one. Plus, the Suzuki axle already has the correct dimensions for the bearings, which is an important fit. At the end of last session, with Young Dan and Mika’s input, we came up with a plan to turn down the pinched section of the axle to match the right right fork leg. We also decided to bore and bush the left leg to match the smaller axle diameter and face it off so the brake plate and heavy washer and main nut will have a large uniform engagement area to better handle the increased braking loads and resist deformation.

I didn’t have a suitable piece of steel to make the bushing so I used a piece of bronze bushing stock I found in my scrap bin. I never throw metal away. I’m the type of weirdo that will pick nuts and washers up off the street and pocket them for later deposit in the junk barrel. Don’t laugh. I almost always come up with a suitable piece of material.

Step by step below in pics, as usual. Only had a cell phone last night, so pics are crappy.

Bonus question for the observant: One of the fork legs requires one more machining operation. Be the first to name it and we’ll send you sweatshirt next time we make a batch.

Adios, mi amigos.

Jason

Pinch-side fork leg before modification. Note the crack. I don't think it's in a critical area considering most of the load is borne nearer the pinch boss.

Locating the fork leg in the milling table vise is a hassle and takes time to get right. I decided to try a new approach. I made an arbor/fixture out of aluminum such that one side fit the collet and the other a slip-fit in the fork axle boss. Chuck the arbor, install the fork leg and locate the table and vise to the suspended leg. Tighten down and check that the arbor travels freely when you raise and lower the quill. Worked like a charm! Had to set the leg three times last night for various steps and this took a minute each time.

Suspended fork leg on the fixture/arbor made for this purpose.

Boring the axle boss on the mill. This old girl is in such great shape the automatic down-feed and shut-off still work flawlessly. These features are usually broken on old manual mills. I wanted the bushing to have sufficient wall thickness to that it would not deform when pressed in. I also wanted a uniform hole for the press-fit. Otherwise I would not have modified the fork leg.