Model A - new bits for the rear wheel - and a plan

 Continuing the investigation and assessment of the Model A, combined with some repairs as we go along, leads us to the rear wheel. Both of the wheels are in a pretty poor state with pitting, missing spokes, and bends of one sort or another. As you will hopefully have noticed I have started posting a lot more YouTube videos on my channel and here is one of them:

As you can see this rim is really for the bin. Around the wheel though there are a few other things that need fixing or replacing; we'll deal with the brake later on in another post and possibly another video but for now there are some small things to be attended to.

First up is a small part which I hadn't really understood very well - the W/NG has one in a mangled state but it's not until I had a proper look at the Model A that I really realised what was meant to happen. 

For long period Ariel wheels were fitted with taper roller bearings and these need an adjustment facility built into the design. As you might expect there are two thin nuts to adjust end play in the bearing but of course these require the spindle to be held in place at one end whilst the other end is free and to do this Ariel provided a flat on the right hand side of the spindle. The slots in the frame lugs for the rear wheels are the same on both sides so this flat requires some packing allow it to fit in the same slot. What they do is provide something like a thimble around the spindle to take up the space and to provide a flat, non-threaded surface for the rear wheel chain adjuster to bear on. 

This was missing. 

To determine the proper material thickness for this thimble or sleeve I tried a few pieces of scrap sheet in the space:

With the sheet selected I cut a strip to more or less the right size and folded it around the spindle:

This prototype is clearly too short!

As an aside, I also wanted to check the thread on the spindle since I had to buy a tap and die set to clean them up. I'm not particularly familiar with CEI threads in this size, so it's best to check with a thread gauge:

This proved it is indeed 9/16" x 20 CEI. 

The next step with the spindle sleeve is to roll it up and weld it. Apologies for the terrible picture!

With some work on the linisher, some fine files and a small hammer we have a nice fit over the flats on the spindle:

This is what the finished piece looks like:

The next job is to make a couple of replacement wheel nuts. The kit of parts came with a couple of 9/16" nuts that had been forced onto the spindle. I recut the thread on the spindle just to clean it up but recutting the nuts revealed the fact that they weren't CEI at all - they were very loose. Since they were quite mangled new nuts are the best option. 

Starting with the appropriate hexagon material we put a bit in the lathe, centre drill, drill in sequence 6 mm, 10 mm and finish with 13 mm which will do as a tapping size for 9/16" CEI.

We'll put a little radius on the corner of the nut to emulate the factory part.

After drilling, the next job is to cut the thread using a 9/16" by 20 CEI tap. With these big threads, it's easiest to start the tap on the lathe to ensure the thread is cutting concentric with the stock. You don't need to cut the whole thread on the lathe as it's a bit awkward.

What I usually do is take the work out of the lathe and finish the thread on the bench. This gives you a lot more space to operate the tap wrench.

There we go, a nice new wheel nut.

The only problem is that the hex I selected is bigger than stock. Good thing I like lathe work, but I can't find any 0.92" hex stock (other than stainless) anywhere...

These nuts are also a bit thick - for years I have been under the misapprehension that a nut thickness is equivalent to the thread diameter - it's not. BS916 tells us that standard nut heights are more of less equivalent to the thread diameter of the next size down, so these 9/16" nuts should be 1/2" high:

Now to the plan.

We know the rim is corroded and bent - we will probably replace it, and the spokes. We know the sprocket needs replacing and the lathe is too small to do it in the chuck. What we will do is this:

1. Slacken all the nipples with the wheel still in the bike
2. Take the wheel out and dismantle it, cleaning the spokes and nipples and storing them
3. Clean the corrosion off of a patch of the rim, to establish how much thickness has been lost
4. Attempt to straighten the bend
5. Decide whether to keep or replace the rim
6. Obtain a sprocket blank or a BSA A65 or Bantam sprocket ring
7. Straighten the bent spindle
8. Build a jig to hold the hub in the lathe for milling
9. Remove the teeth with a grinder as far as possible
10. Use the jig to reduce the sprocket diameter with an end mill and create a weld prep, or a step if it turns out to be cast iron...
11. If the hub turns out to be steel, remove the inner part of the sprocket ring with an end mill, holding it in a large pot chuck on the rotary table
12. Weld the teeth from the sprocket ring in place, or drill and bolt if it turns out to be cast iron
13. Rebuild the wheel.

I made this sketch of the setup:

The alternative is to do nothing - fit a new chain and let it wear prematurely, perhaps until Karol of the Slovakia Ariel Klub has his special adapter sprockets available again.