Charlie's Shed - recovering threads

 OK, so this is a commonly available AJS/Matchless frame stud, used under the seat nose to unite the front and rear frames. I can get a replacement very easily if I want to, but what if it's a unique part? 

The object of this blog post is to illustrate how to recover a part like this in the workshop. This stud has obviously been loose at some point in its life as the thread is worn away beneath the frame tubes where the rear frame fits over the stud.

Start by stripping it out and cleaning it on the wire wheel. We are going to be welding some overlay into that worn area and we don't want anything contaminating the weld. When you have it clean, use a thread gauge and a micrometer to make sure of the pitch and diameter - it's quite easy to mix up thread pitches, and you will even get the wrong nut on a thread for a few turns: something you don't want to do with a thread cutting die.

It would be nice if we had some sort of facility for rotating parts like this whilst welding, but if you work towards yourself it is quite easy to do a quarter or a third of the diameter at a time: 

A few minutes on the lathe reduces the welding to a plain shank suitable for thread cutting. Since there's a little bit of the original thread remaining on the stud, it's easy to start the die to recut the thread.

A few minutes later and the stud is good as new.

Model A - chainguard

 The latest in a long line of broken bits waiting repair before they are painted is the chain guard. 

This is a pretty simple bit of welding. Initially the mounting nut is missing so I have replaced it with a new un-plated 1/4" CEI nut welded in underneath and I've filled in the worn hole as well:

The next bit is this gap which is a piece of material worn away as the chain rubs away at the chainguard. This is a bit more complicated.

First job is to chop it out with the Wiss snips and the Dremel. Next we can make a repair patch from a scrap of 18 gauge steel sheet cut to roughly the right shape, folded in the vice and refined with the linisher.

If you're careful, you can get it close enough to weld in without any filler rod which saves clean up time and reduces the heat (and hence distortion) going into the work. This wasn't one of those occasions, as I needed a bit of filler to close the gap at one end.

It's not too bad though.

Next is the other side - a bit that had been rubbing against the rear mudguard and worn a chunk away. That's it for the welding now.

With the paint finished it looks a lot better!

Model A - front stand

 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.

Model A - Kickstart spring cover 2

 After lots of input from the Ariel community, I now understand how the kickstart spring cover is supposed to work. 

There are four parts in play, illustrated by this page from the parts book:

• LS254, the kickstart lever. I think I have the right one
• LS262, the kickstart bush. This comes all the way out of the end cover up to the end of the shaft, LS253. The bush is 1 3/8" OD
• LS263, the distance piece. Andrew H of the AOMCC tells me that this is 1 1/2" OD, so the wall thickness must be something like 1/16".
• LS264, the spring cover

The big reveal is that it is the distance sleeve that keeps the spring cover in place, and that it is itself kept in place by the kickstart lever. This means the spring cover, LS264, must fit tightly enough around the bush LS262 to be retained by the 1/16" thickness of the distance piece LS263. 

The other thing I've seen is that the top of the spring cover is not flat, but follows a nice radius. The former has been back to the lathe for reshaping:

I've prepared another bit of sheet, by cutting it to size, squaring the ends and removing the paint:

Before we start on that, I found a piece of exhaust pipe the perfect size for the distance piece. I made a wooden former so I could cut it to length in the lathe and form a short radius on the end.

The radius prevents it sliding towards the gearbox quite successfully and it fits rather well behind the kickstart lever.

I formed the spring cover in the same way that I did last time but there was no way it would shrink far enough to get to the required inside diameter for the kickstart bush, so I ended up cutting darts in it and welding them up

There is a bit more work to do, but all the bits fit together. I think the spring cover is too long but I always knew I would have to trim it and I need to finish the welding. Lastly there will be a hole for the spring to pass through.

Before we get into that though - this is my latest invention for welding - an arm rest! Makes controlling the torch so much easier:

The arm rest made finishing those tiny welds much less stressful. The welds were backed with a curved copper strip which as I have shown before minimises the dressing required on the back side and gives you much more control when welding this thin material. It's been welded, ground out inside, straightened, ground outside and so on...

Next job is to drill a 1/4" hole near the edge, and file it oval:

Then I've used a drill to form the material such that the spring can pass through:

The spring is wound in from above:

In the video, the spring cover has been trimmed to length and fitted:

It's not perfect but it's nearly there. I shall raise the edge of the cover a little more since the whole assembly has to account for end float in the kickstart shaft, and there is a bit more clearance than I would like.

Model A - Kickstart spring cover

 When you have a few old bikes, and you use them, and especially if other people use them, you must expect a few diversions from your ongoing project whilst you fix the other bikes in the fleet. The Square Four has absorbed a bit of time recently and it's now become the daily rider again while the hunt must have takes a little holiday in Norwich.

Therefore, the Model A has taken a bit of a back seat but it's time finally for the next job. This is the tin cover for a kickstart spring.

To start the job off, we can measure the machined register that it fits on the kickstart cover and then we can work out how long it needs to be by measuring the spring.

I'm going to fold the cover up from a strip of 0.9 mm thick steel around a wooden former which I will turn on the lathe from a chunk of sapele, part of an old door.

I've screwed and glued this former to a suitable piece of timber such that I can hold it in the vise

Here's the first try, cut from a bit of sheet with the aviation snips to a suitable width and rough length. With it held in place on the former some tie wraps, I can mark the end and trim.

We'll do a little trial fit on the job:

We need to bear in mind that this cover is supposed to turn with the spring. The spring fits nicely inside it but I suspect it's rather tight on the gearbox end cover.

The only way to find out to tack it together. A couple of tacks show that it fits nicely will turn on the register on the gearbox end cover, so I fully weld it and dress it on the linisher.

The next step is to work out how long it needs to be. I believe that I will need to fold it over such that the inner diameter just fits the kickstart shaft bush.

A little session with the Wiss snips sees it cut to approximately the right length.

Attempting to spin the end over on the lathe was an abject failure - the wooden former just flew out of the chuck so I returned to doing it with a hammer.

That worked reasonably well, and it fits:

There's something fundamentally wrong though:

With a lot of help from the AOMCC, I've learned that LS263 holds LS264 in place and is itself held by the kickstart lever.

Time to try again.

Model A - that kickstart lever again

 Well, yesterday it was finished. The cotter pin went in way too far and would need replacing, but it worked. However, there was an itch...

I suppose I am a bit obsessive, but I couldn't put up with having to remake the cotter because I had machined the shaft wrongly. I filled the slot up with weld.

A few minutes later, I had re-machined the slot; the shaft is 3/4" within the kickstart lever and the slot has a maximum depth of 0.150" - the easiest way to measure this accurately is from the bottom of the cotter slot to the opposite side of the 0.75" diameter, so you measure 0.600". The slot is bang on the correct depth, and the 0.375" cotter pin fits perfectly.

All I need to do now is cut the spare length off the cotter pin and radius the end, like this:

Now it's finished. Definitely. Apart from the spring cover...

Model A - rear brake pedal

 The rear brake pedal shaft is one of those areas where you see the horrors perpetuated on old motorcycles through years of neglect and changes of ownership with varying levels of skill. Having removed this one to rebuild the footrests and replace the brake pedal spring we realise that it is in fact a bit mangled.

To start with, we can see that the thread has been cut to a BSW form - Ariel would not have used BSW here, the thread would originally have been CEI. We will build it up with weld and cut a new thread to the right size.

That pin across the right hand end as we look at it forms both the stop and the fixing point for the end of the spring. Part of it, the fixing point for the spring, has broken off. It proves impossible to knock out though it is listed in the parts book as a separate component, so we drill it out.

Here it is, illustrated in the 1930 parts book:

The other curiosity which I didn't understand initially is how the shaft is lubricated. There was no obvious grease nipple but under all the gunge a hole appears half way along the shaft, which is clearly to let grease into the central reduced area - and an ex-nipple on the end which has had some attention from a hammer.

I've said many times that the AOMCC is a wonderful club to be associated with and a few questions posted on the Facebook page yielded this drawing from 1925 and signed by Val Page himself. The drawing clearly shows the same formed nipple on the end of the shaft that the later Ariels used until the end of four-stroke production in 1958.

The difference between this and the later bikes is that whilst the later bikes use a nut to retain the brake pedal on a parallel fixed shaft, this application uses a nut on a taper to retain the pedal on a rotating shaft. Therefore when you want to remove the pedal for adjustment, you have to undo the nut and knock the end of the shaft to free the taper. Guess what happens? The nipple gets flattened...

To start with we're making a new pin on the lathe. I didn't intend to use a piece of stainless, but at the time I couldn't find a quarter inch piece of mild steel round bar - but no one will ever see this, so it doesn't matter if it's the wrong colour.

I've cut a semi-circular channel in the end of the short bar to locate the brake pedal spring. It's a simple matter to chamfer both ends and press it into the pedal shaft.

This is how it looks.

This is apparently the correct spring - I got it from AOMCC Black Ariel spares some while ago and I'm assured it is the right one, though it looks very stretched when it's in position.

See what I mean?

The next step is to build up the mangled thread and nipple. This is none too tidy but hopefully there will be enough material to turn it to 7/16" without firing up the TIG set again.

The first pass at turning to size shows, as it often does, that more building up is required:

That done, we can start forming the shapes according to the drawing with a radius tool to form the curve and shape the grease nipple:

I seem to have missed out a step here - I've forgotten to photograph the drilling out of the grease hole, which is 5/32" per the drawing. The next step is to cut the 7/16" CEI thread. 

Here it is on the bike with the brake pedal attached:

We will need to be very careful when moving the pedal - using a socket or something over the nut to avoid damaging the nipple!

Here's an overall view. That pedal is very high!