Model A - investigating the rear brake drum

 In common with several Ariels of this vintage, the Model A has a rear wheel sprocket which is integral with the brake drum. This in itself would not be a problem were it not for the fact that the sprocket teeth are worn out.

The whole assembly is far too big to go in my lathe so what can I do about removing the sprocket teeth? Some options:

• Can I spin the hub in the rotary table, mounted on the workmate and remove the teeth with a fixed angle grinder?
• Can I build a jig to carry the whole hub in the milling table, and remove the teeth with an end mill?
• Get Draganfly to do it?
• Find a local enthusiast with a bigger lathe?
• Find a better hub?

One thing I have discovered - a BSA A50 chain ring has the required 47 teeth to suit the 5/8" x 3/8" chain I need. An Ariel 4305-32 looks similar.

We'll have to think about that a bit more. In the meantime, we'll have a look at all the other bits in that area so that we can work out what we are dealing with especially since I'm expecting to place an order with the Ariel Klub Slovakia shortly. 

The brake plate is all present and correct.

The brake plate dust exclusion ring is a bit mangled - I have a feeling you can get these new as they are spot welded in place but since the 1930 Model A doesn't have a plated ring here I may repair it and paint it.

In the brake drum we have the 'new for 1929' ring that retains the spoke heads should they break off. Ariel must have had some incidents with brakes seizing or wheels grinding to a halt through loss of spoke heads. Not a pleasant experience to contemplate! It's all very greasy in there.

Equally greasy is the back of the brake plate but at least we have some shoes which are whole and a set of springs and a cam.

The cam bush is very worn indeed and will have to be replaced.

It's fitted through the brake plate and there is a nice little gas weld on the inside:

Here's the cam. I don't think there's any doubt that we will be buying new ones!

Something else that has caused much discussion on the Facebook group is what brake lever this machine should have. This part is definitely Ariel, but it may not be 1930 - however it's not much later, perhaps 32. Checking the parts lists doesn't reveal very much from any of these years - they all show a relatively short stubby brake lever. The various members that contributed to this discussion revealed quite a variety of brake levers including this long curved one - so go figure.

It did have a lot of bends in it. I've taken one out and this will probably sit better with respect to the mudguard stays - we'll have a look when it goes back together.

Moving on to the frame, we'll take the opportunity to clean out the threads for the chain adjusters

There's something odd here - this looks like a braze repair around the sidecar mount. The mounting should exist as a more or less complete ring without that lump of material between it and the frame lug.

The brake plate torque lug is present on the inside and both of the top hat washers are present.

Moving to the other side of the bike, this all looks good and the stand stops are in very good shape.

Missing from this side is the little flattened tube that's used to protect the wheel spindle thread from the chain adjuster. They are often mangled - we will have to make one of those. 

At both ends of the spindle, the wheel nuts are not in the best shape. The left hand side won't run all the way down the spindle - it looks like it's had a hammering at some time.

FH - preparing the primary drive

There are a lot of work faces appearing on the bike now the cylinder head is ready to go on; the timing side can be assembled once the automatic timing device is finished and the primary side can have the clutch fitted and the primary chain built up. For no particular reason I've elected to start on the primary side mainly because I don't have the bench space at the moment to do the ATC. Here I've fitted the 19 tooth standard gearbox sprocket with a spare secondary chain and torqued up the big nut.

 

The spare length of chain I had knocking about was too short so I've taken this unusual approach of wiring it through the holes in the sprocket just to allow me to use the back brake to tighten up the gearbox sprocket nut.

With that done we can start looking at fitting the inner primary case half. What's different about this bike is that it's fitted with the fully enclosed rear chain case (FERC) something I have not yet experienced on an Ariel. There are a couple of unusual mounting points, one of which is this nut which is attached to the front half of the FERC.

It's a 1/4 in CEI bolt which needs a special tab washer to retain it to the inner primary chain case casting and to prevent it coming undone, dropping into your primary drive. The special lock washer is available from Draganfly but unfortunately I forgot to order one. I've made this one out of a piece of 0.9 mm sheet steel.

Here it is with the bolt tight and the tab washer folded up.

For the record I have fitted that 1/4" BSW screw with low strength threadlock from Loctite. The castellated nut retaining the engine shaft shock absorber will need a split pin to prevent it falling off.

That's it for now; the next step will be to think about the clutch. I expect to find some parts that are in need of replacement so I'll have a look at the clutch soon to get those on order.

For now, let's just record that I fitted a new length of primary chain and an old spring link just for now. I'll have to order a new one. 

The other thing to bear in mind is that the chainwheel is rubbing on the oil catcher so I'll have to sort that out before I put primary case outer cover on.

RE Interceptor - chain & sprockets

 A nice little jaunt this evening to see the grandchildren and to help son Thomas replace the chain and sprockets on his 2019 RE Interceptor, supplemented by spaghetti & meatballs to keep us going.

The gearbox sprocket is easily accessible under an alloy cover retained by three screws and the gearchange lever:

The bike has done about 9,000 miles on the original parts and it's high time they were replaced. The tab washer and nut were removed with a socket and breaker bar before we removed the chain. We slackened off the rear sprocket bolts as well. The chain is endless, so we get the Dremel out to slice through a side plate and grind back a rivet:

The rear sprocket is retained by six M10 screws and nuts. This is the new one, bought from Hitchcocks:

You can see the wear on the gearbox sprocket:

All done and back together in a couple of hours. Next stop, tappets and an oil change.

Before I forget again...

This sprocket has 25 teeth. Standard solo is 24; 23 for sidecar:

 

This one has 44 teeth; you can get a 40 tooth version as well:

And this one has 19 teeth hidden under the chain. This is standard:

The rear brake drum should have 47 teeth.

Tomorrow I need to order the chains.