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 punch and a series of progressively increasing twist 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 that 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 chainguard 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 - work faces

 The Model A has been on the bench a while now and I've been spending time investigating what I've bought and reminding myself of the parts I've made or acquired over the last few years. 

As a man who likes to tinker in his workshop - who doesn't - various work faces have opened up as I've investigated the machine. 

One is the broken dynamo and it's clamp. Removing the dynamo I realised that I didn't understand how it was held in place with only half a strap - pleas to other club members soon yielded a few photographs showing the bits that were missing. 

Taking the dynamo off showed me quite how bad the damage was. Both of the end castings appear to be broken - the drive end is in two pieces and I had to drill out one of the screws, but worse, the armature is actually bent. It looks like it's been dropped on the floor or had a whack from something at some point.

For the record, the armature is 157 mm long and you can get new ones - Feked have them.

The secondary of investigation is all of the tinware on the drive side. I started with the clutch dome but I have various repairs to do to the primary cover and the dynamo chain cover. 

This led to me looking at the clutch and the gearbox because of course the aperture in the primary cover dictates the movement of the clutch to some extent during the tensioning of the primary chain.

Thinking about the gearbox and it's range of adjustment led me to the gear controls, most of which I have already made. This leads naturally to the fixing of the fuel tank because of course unless the fuel tank is firmly bolted down (and I have new rubbers for that) the gear controls can't be set up. 

If that wasn't enough I've been looking at the front wheel and loosening the spoke nipples. I'm not going to go any further than that though - I was trying to establish whether the front wheel rim could be used or whether it was too far gone. 

The other area I've been looking at is the Lucas H52 headlamp, it's shell, and the mountings. The shell was quite bent and whilst I had the hammers and dollies out to sort out the clutch dome I knocked the dents out of the headlamp shell. It still wouldn't sit straight - it's aligned to the offside - because the mounting bars are also bent...

I think that's enough for now. I promise that I won't take anything else to pieces except perhaps for the gearbox outer cover - the kickstart doesn't seem to work and I can't get first gear!