Model A - primary chain cover

 As I've said, probably more than once, the primary chain cover and it's associated parts - the clutch dome and dynamo chain cover - have a number of problems mostly associated with splits and broken welds. Nothing fundamental is missing apart from a couple of brackets and there's nothing we can't fix.

You've already seen that I've made a start on the clutch dome in a previous post so today we are going to start on the chain cover proper. 

The chain cover supports the forward end of the rear chain guard and the bracket for this has cracked and been repaired with a piece of thick sheet and several ugly rivets. Fortunately it has been fixed in more or less the right place:

What we will do, to start with, is retain it in this correct position with a short weld:

Next we will remove the rivets and start to reshape the bent and twisted metal. This is a simple as using a centre bunch and a series of progressively increasing twisted drills until the rivet head comes off leaving the stem still in the hole, when the part will come off with a little tweaking and no damage.

With that lower bracket removed we can dress out the distortion in the chain cover .

The next job is to make a new bracket in the style of the existing brackets at the front end of the chain cover. In common with those brackets this is cut from 2 mm thick steel sheet on the bandsaw, linisher, and pillar drill. Here it is in position for a trial fit:

It is supposed to fit inside the curve of the chain cover and be retained by two spot welds, the holes for which are still there. This is quite a weak design and I'm not at all surprised at the welds failed.

The new bracket needs a bit of bending to get it to fit properly at both ends.

That's it for this part of the repair. What you can't see is that I have made a short weld along the edge of the clutch aperture to retain the outboard edge of the bracket.

The last bit of this job is a split along the bottom edge which has opened out probably due to the stresses remaining in the part after it was pressed to shape. I've used three clamps to draw this together again for tacking:

This is not the most tidy job, but I realise now I had the current too low. I try to keep it down to avoid blowing through the thin metal but you need it high enough to make the metal flow! I laid too much filler rod onto this to make sure I wasn't burning holes.

It will grind out ok, and the penetration is perfect. 

Getting near the end now - two holes to fill. A thin copper backing lets you puddle in some filler rod:

I've not taken a picture, but with a copper backing there is virtually no dressing to do on the back of this weld.

Back to the rear chain guard mount again, with the rivets removed and the holes plugged we can just weld up the seam along the edge of the main primary chain guard:

This is a tiny little autogenous butt weld with a little bit of filler rod part way along.

That will do.

Quite a bit of cleanup though - we will do that tomorrow.

I'm calling this done.

Model A - dynamo chain cover

 I've mentioned the dynamo chain cover more than once and it's now risen to the top of the list for repair. I'm part way through the repair of the primary chain guard and I want to make sure that all of the items that affect its position are in place before I finalise the welding.

The dynamo chain cover is in pretty good shape really apart from the fact that the chain has at some time worn through one of the feet and it has disappeared.

It's a simple matter to make a new one out of a bit of 16 gauge steel sheet using the pillar drill and the linisher. More difficult is to drill out the old spot welds and release the remains of the original foot. Here's the new bit in place with 5/16" holes where the spot welds used to be:

It takes a surprising amount of material to make a plug weld into those holes. The tricky bit is to support the work on the copper heat sink and make the welds without burning the original material away. However it soon done and fitted back in place for testing prior to clean up:

Model A - crankshaft shock absorber 2

 Well the Lambretta cush drive spring has arrived and fitting it up you can see why AOMCC singles expert Peter said that it wouldn't fit with the '26-'27 pattern shock absorber, which is what I have here. There is no way that you can get the nuts on to start this compressing the spring.

Fortunately, the 1930 pattern shock absorber is available from Karol Burger of the Slovak Ariel Klub.

Even more fortunate is the fact that Karol stocks two types of sprocket, one with 19 teeth and one with 23 teeth. What I have here is a '26-'27 19 tooth engine sprocket which is obviously for sidecar use: 

We know from experience with both the Huntmaster and the Square Four that bikes of this era are usually low geared (even when specified for solo use) so we do not want to compromise our budget and our riding experience by buying the wrong sprocket. This makes me feel a lot better about having the wrong crankshaft shock absorber!

We won't do anything else in this area until we have the new bits from the Slovak Klub.

Model A - crankshaft shock absorber 1

 It's all go here. The latest investigation is to look at the crankshaft shock absorber, which it turns out is missing a few vital parts!

These are the sections of the parts book that deal with the crankshaft shock absorber. I had assumed, wrongly, that because there was a shock absorber in the clutch there would not be one on the crankshaft. However club member and black Ariel spares coordinator Lee, who is currently restoring a 1928 Model E (which has a Burman box) tells me that his bike has a shock absorber in the clutch as well. Therefore I am now given to believe that all the bikes have a crankshaft shock absorber.

I'm missing the spring and both the collars that it sits in. I'm told that a Lambretta spring maybe useful and I have a dimensions for that and I actually I have ordered one. 

The spring collar A6/714 is missing and I have no picture at the moment. However the function of these parts is fairly obvious so I'm confident that I can make something up.

This is the bit that Sturmey Archer call the spring retaining collar. It's listed at Draganfly but unfortunately out of stock at the moment. I'm sure we can make one of these.

This is the A6/712 sliding member:

As you can see, the spring sits on a 33 mm diameter. The Lambretta spring dimensions are:

• Free length = 37.5mm
• ID = 35mm
• Wire dimeter = 6.85mm

The diameter should fit nicely. It looks like this:

As you can see, there is only two wire diameters in that 37 mm length, so it should compress considerably - maybe to the 20 mm I have available!

Model A - jobs for the mini-lathe

 Like all vintage bikes, there are lots of bits that are broken or warm and that you just can't buy. For enthusiasts of the homework shop these bikes are great fun. 

I don't think I'd make much use of a milling machine but the mini-lathe, as usual, will get a bit of a workout - in fact I've made lots of bits on the lathe for this machine already.

• Stand bolts 
• Mudguard bolts and special nuts
• Chain adjusters and lock nuts
• Clevis pins for the brake rods and gear controls 
• Brake adjuster knobs
• Front brake spring box

There are many more bits to make, and the purpose of this post is to record them so that I don't forget:

• Crankshaft nut 
• Tank bolt 
• Gear change rod 
• Luggage carrier / mudguard stay bolts
• Footrest bar 
• Footrest spacer 
• Battery strap nuts 
• Parts for the crankshaft shock absorber
• Clutch spring screws
• Missing studs - for example for the front of the primary chain guard

That should keep us busy all winter!

Model A - dynamo engine plate covers

 There's a lot of splits in sheet metal components on this bike - not surprising after 95 years of corrosion & vibration. This is the top engine plate cover over the dynamo, and one of the bolt loops is missing. I'm replacing it with a bit of sheet cut from the side of a dead dishwasher - 0.5 mm thick:

One of the benefits of having quite a small TIG welder is that you can do tiny little things like this - this was set at 15 amps:

This is the front engine plate cover. Despite the fact that the one in the parts book is slightly different (it has four bolt loops) it appears Ariel modified this part without reflecting the change in the parts book illustration - I'm saying this because others I've seen are the same as mine - go and look at the one in this post, about the dynamo clamp.

Model A - the gearbox

 As part of the Preliminary Investigation season here on Amelia's Blog, today we are having a tentative look at the gearbox.

The reasons for this are threefold:

• I can't engage first gear 
• The kickstart shaft is wobbly 
• I'm concerned that the kickstart shaft is much too long

The gearbox is a Sturmey Archer LS type heavyweight gearbox, configured for Ariel. These are quite well documented though spares support isn't good. As you probably know, it's a 3 speed hand change box.

The end cover is easily removed when you have taken off the six neat little shouldered nuts, one of which is a special nut with a grease nipple that feeds through a hollow stud into the top of the gearbox.

What greets me is a robust and simple cluster, seemingly intact and free of damage - there's no hint as to why it doesn't select first. 

Here's the end cover and kickstart shaft from the inside. At the bottom of the picture is the main shaft and bearing and within that the clutch worm.

Here is a close up of the cluster just for the record.

Right after I took  this picture I discovered that if you engage first gear with the end cover off, the cluster goes flying across the workshop floor!

After a session in the parts washer, we can have a better look. This is the Kickstarter shaft - there were a number of alternative lengths of these available for different manufacturers but looking at the catalogues it appears that most of them must have used splines because the makers make special mention of the cotter slot for the kickstart lever that was used for Ariel.

The kickstart bush also comes in various lengths to suit the shaft. This is the 1 3/8" extension the Ariel parts book talks about:

With the kickstart shaft at the rest position and the lever fitted to suit the cotter slot, we can see the lever is in totally the wrong position. That shaft is not original, but would be more suited to the box in the horizontal position, like a Panther...

Here is another view which shows you the excess length in the kickstart shaft. Note that the silencer is further outboard than it should be by that stack of washers, so correcting the silencer mounting will leave even more clearance under the kickstart lever.

That spring isn't right either - there is a 45 mm ID spring used by Norton, and a 49 mm ID spring. Guess which one this is...