As usual, I will be using the services of Mr Tony Cooper of Halesowen to rebuild the magneto for the Model A. I spoke to Mrs Cooper today and learnt that Tony would be able to rebuild the BTH KC1 for me. He's done the magnetos for both the FH and the W/NG, and they are excellent - the estimate for the Model A was a maximum of £250 and it would take 14 to 21 days.
This is how the magneto looked when it arrived. It's more or less the right period for the Model A but as you can see it is a slack wire advance magneto - Ariel specified a tight wire advance magneto. In theory, slack wire advance is a better option because if you lose the cable, the engine will still run optimally at speed - but it might be rather hard to start!
First job then is to remove the magneto. Fortunately this side of the engine is relatively clean and it's quite straightforward - it's just the same arrangement as the W/NG, built 12 years later.
Underneath I was surprised to find only two bolts holding the magneto down - the magneto is set up for four bolts, the W/NG uses three.
With the magneto chain cover removed we can have a look inside for the first time, and it's all pretty familiar and pretty clean although the chain is very loose indeed:
All you have to do is remove the magneto retaining nut and then use the usual magneto pinion puller to release the taper:
You can then remove the two bolts holding the magneto to the platform and lift it out of the way. There appears to be a seal between the magneto and the chain case which looks like it is a felt seal sandwiched between two pieces of tin - it's black and oily at the moment so when it's cleaned up we can have a proper look.
Here are a couple of before pictures of the Magneto after it's had 15 minutes of fame in the parts washer:
Looks pretty good and turns easily. There's something wrong at the points end though - the bolt retaining the points to the armature makes contact with the brass end cover. One of these parts must be wrong, probably the end cover because in this arrangement the magneto will always be earthed and will not spark.
Whilst working on the forks I made a little side project out of the front stand. Whilst I have the forks in bits I want to make sure that the mudguard and it's stays are all in the correct places, which of course includes the front stand and it's fixings. Sorting that out will also allow me to trim the front mudguard to the right length
We have the original front stand with the Model A, but unfortunately it's rotted out. I always seem to end up welding these stands for one reason or another, and this one is no exception - the stand retaining clip is missing as well.
I've had some suitable heavy wall tube knocking around since the FH project which needed its front stand extending by about an inch. It's a blessing that Ariel didn't change their design every 5 minutes and the stand material used here is the same as is used on all my other bikes - consequently there's about three feet of suitable tube in the material bin that I can use to fix this stand.
I use the Rothenberger Superfire 2 blow torch to make freehand bends using the old stand as a pattern and eventually end up with a complete bottom section that I could weld to the old arms
The linisher is very useful for squaring up joints in tube work which in turn makes a very straightforward autogenous butt weld:
Before we go any further, we need to make the clip at the back of the stand to position it in the right place to get the arms the right length and in the right orientation. This is the clip on the W/NG:
I've made this out of a piece of 16 gauge steel sheet cut to a strip around 1 in wide and I've drilled a 1/2 inch hole in the strip to receive the annular part of the special nut which is used to retain these stands. I folded the strip in half and cut a slot to clear the 5/16 inch bolt to which the stand is fastened.
I made a few of these special nuts on the lathe some while ago, probably for the WNG. The Model A was in the pipeline at the time and I knew I would need a few:
I've used this electronic level and some pictures provided by fellow club members to set the stand in the right place to determine the position of the hole for the clip:
With the hole marked and drilled, and the mudguard cut to the right length, I fixed the new stand section in place with the new clip:
With the bottom section in the right place, I can measure the length of the arms and tack them in place:
It's a very straightforward job which finishes this area ready for paint.
As usual I seem to have created a benefit rag tag collection of different work faces as I potter about the bench working on the Model A amongst more household stuff.
To summarise:
I've reassembled the front forks and I'm starting to identify small jobs while I wait for parts from the AOMCC
I've had a look at the front wheel and brake plate and found nothing of concern
I've spoken to Tony Cooper about getting the magneto rebuilt, and that now has to come off
Spoken to Joe the Carb about getting the 6/112 rebored and a new slide made
I'm in the process of repairing the front stand and finalising the bottom of mudguard
The dynamo is in bits on the bench waiting for a clamp to help me remove the new bearings for shimming
The wheel rims and spokes are on the way from Devon
I guess that I have been shying away from looking at the girder forks for a while - it occurred to me that I have never dismantled a set of forks like these but having dived straight into it, it's dead easy.
The first job was to make sure the back of the bike was strapped tightly to the lift table and then use the scissor lift to raise the engine a bit. Then I gingerly loosened the front wheel in its clamp and confirmed that everything was stable.
Pulling the forks about revealed a lot of movement and I made a little video:
There you go - clearly a number of problems there.
Removing the spindles and replacing them with scrap round bar allowed me to have a look at the links. The part you would call the bottom yoke in a conventional telescopic fork is called the fork crown by Ariel, and the links attached to the crown at the bottom are pretty worn:
Both sides, as you can see. This means the links will need bushing or replacement; the top ones are worse.
Fortunately removing the crown and steering column revealed that indeed there were no balls in the steering head bearings, so that will account for a lot of the movement.
I will probably clean up this area and leave it in factory paint as it is in quite good condition.
The steering head races had two balls left in them. We will clean them up and see how worn they are.
Ariel call this bit the ball head clip - it carries the handlebars and the spindle for the top links. Said spindle was absolutely solid in the clip and I had to resort to the splendid Rothenberger Surefire 2 to warm the grease up and get it to move.
The spindle came out eventually - but look at the state of it. The bike has also been used with the spindles loose which has worn most of the thread away and part of the link too.
The main girder assembly looks pretty good:.
I'll repair these worn areas though - it looks like the mudguard has been loose and has fretted the fork leg. These will build up with weld.
Whilst the girder fork assembly is still a bit contaminated with old grease, I'm quite confident that the spindle bores are good enough.
I spent a while getting all cleaned off the next afternoon. The two races that fit into the frame are chipped but with new balls seem to work ok.
I'm going to replace the spring while I can. You remove these by tapping the end with a hammer and a punch to unwind them from their fixing spiral:
This is the lower fixing - the upper one is part of the main girder.
You can see that the spring has opened up - it must be quite soft.
I rebuilt the forks with the new balls in the steering head to determine how much play I had solely coming from wear in the links and spindles. With these old parts in place, the wheelbase varied 3/8".
I've been in discussion with the Black Ariel spares man for the AOMCC and have some new parts on the way.
In a spare moment while waiting for parts I thought I would have a look at the carburettor provided with the Model A kit. I've not touched it since it arrived all those years ago:
In the last couple of days I have removed it and giving it a good clean so that I can discover what's missing and what's broken.
It's the original carburettor and is pretty worn but it cleans up well:
Standard fitting for the 1930 Model A is a 6/112 carburetter, now called a Pre-Monobloc, which is 1" throat diameter, and here is the evidence:
According to the Amal book, jetting is as follows:
Size: 1"
Main Jet: 4/042-160 (still available new)
Pilot Jet: none
Needle Jet: 4/061-106 (still available new)
Needle Position: 6/065, position not recorded
Slide: 6/0524
Float chamber: 14/004
The slide is really bad - probably the worst wear I've ever seen. The grooves around the top of the needle are in pretty poor shape too - we should expect this and the needle jet to need replacement
The choke slide spring appears to have been cut short - fortunately I found a spare one in the carburettor bits box.
The float chamber appears to be correct - I didn't expect the bowl to be held by those two brass fittings at the bottom - there must have been a gasket in there
Initial observations:
The main jet is missing
The needle looks very tired
If the needle is tired the needle jet will need replacing
We probably need another cable adjuster
The slide is very bad which probably means we need a rebore from Joe the Carb.
We need to understand how the float chamber fuel feed was sealed - possibly by some sealant in the thread
That's it for now - it's back on the bike and we can start some other jobs.
In my quest to put the primary side back together to clear the decks before starting to investigate the forks, we come to a little painting job on the chain cover and clutch dome.
I've cleaned up the clutch dome with a 40 grit flap wheel, 60 grit paper, and degreaser.
This is the first coat of Tractol 816 grey primer supplied by Smith Allen to go under the Tekaloid 318 gloss black.
It goes on easily and dries very quickly but it does seem to hold brush marks and attract dust.
Twelve hours later, with a slightly larger brush I applied first top coat:
It goes on very nicely but I seem to have trapped quite a lot of bubbles. Perhaps I am over working the paint.
I put a second coat on the next day - after nearly 6 hours it was still slightly tacky. The second coat could be handled in 24 hours and these two parts are now hanging from the workshop ceiling to cure.
As everyone says, the depth of the gloss is amazing.
