Model A - Sturmey Archer clutch

 I feel like I am in a bit of a vacuum now that the long running kickstart shaft machining project is finished, so I will pick up the easy option of tidying the workspace while identifying something to do from amongst the myriad of jobs. The first one that springs to mind is the clutch which has been laying about underneath the bike.

It's in pretty good shape but it had a couple of bits missing that I have replaced over the last few months so today I'm going to strip it and clean it up before reassembling and fitting it back on the bike. I will then rebuild the primary side and put the chain cover back on - I will paint it if it's warm enough.

With a bit of help from the Raleigh owners club I learned how to strip it down - it's all down to ten 1/4" nuts which are uselessly staked in place.

The shock absorber looks very good and I am tempted not to replace the rubbers but disassembly of the clutch centre does not go quite according to plan and I end up with balls and rollers all over the place!

There are 17 rollers and 16 balls here, exactly as per the parts list but I don't really understand why you would design a bearing with mixed balls and rollers. Perhaps someone can educate me.

A sample roller measures 0.250" diameter by 0.249" long and a sample ball measures 0.249" diameter. I shall replace them all.

Cleaning up the clutch centre reveals this little hole, with a partner on the opposite side. Are these intended to allow oil to be introduced into the bearing? Or are they drains?

A couple of hours with various wire wheels and brake cleaner brings the parts up very nicely for inspection, but there is little damage.

I have a couple of new spring cups from the Raleigh club and a set of new springs, plus the two new clutch springs screws that I made a few weeks ago. Currently these have standard quarter inch washers but it is noticeable that the originals are very tight on their screws so we will make a couple of replacements on the lathe, from this bit of 3/4" round bar:

I've just parted off a couple of washers to match the length of the original ones. We will chemically black these later.

Next up, it's a bath of thinners, the wire wheel, and a dose of Scotchbrite to bring the plates up. They all have a bit of burring on the tangs so we will have to dress those with a file.

Saying that though, I think it's probably more important to look at the basket than the plates. I'm convinced that burrs like these produce more resistance to free clutch plate movement than the burrs on the plates: 

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 - fitting the kickstart lever

 The last step in the long story of the kickstart shaft project is to machine the flat for the lever cotter pin. We are back on the lathe with the vertical slide and will use this setup to machine the slot:

The cotter pin is about 3/8 diameter so we will use this 3/8 end mill to cut the slot.

This is the last pass of 3/8 end mill - and it's a pass I wish I hadn't made. I was very near the end and used a trial fit to find that the slot I was milling was about 1/32" too shallow. For some reason I decided that it would need another full turn of the lead screw to finish the cut - completely forgetting that the lead screw pitch is 1/16". So now that slot is too deep.

I could weld this up and re-machine it, but the cotter pin still fits and stays in place properly. I guess I will leave this until it becomes a problem - I can't get a 3/8" bolt in there, which would be possible if the slot was any deeper.

So for now, the kickstart shaft is finished.

Model A - layshaft bush

 With the kickstart shaft nearly finished, we need to think about the bush for the lay shaft. This fits in a bore in the end of the kickstart shaft: 

The bush will be a top hat shape to accommodate the end of the layshaft and to determine the end float of the low gear pinion. It's going to be made from this piece of SAE660 bronze:

First job is to reduce the diameter to nominally 1” to pass into the shaft with a few thousandths clearance:

Next, we reduce the diameter such that we have a few thousandths interference fit in the 7/8" bore, and add a small chamfer to aid assembly. That done, we can bore it in steps up to 5/8" - our shaft is 11/16", but we will do that last bore in situ.

Parting off the bush. The hang out here is not ideal at all, and I believe I may have knocked the stock out of square in the chuck - it would have been far better to do this job with the revolving steady.

No matter though, this does not affect the working diameters and we can face off the end of the bush if necessary.

The top hat bush, mostly finished aside from the layshaft bore.

It's not as tight as I would have liked, so I have fitted it with Loctite 603 retainer. This won't be cured until tomorrow.

This is the last job for the lay shaft bush - it's been fixed in place and the Loctite has cured overnight so it is now being bored too 0.6875" for the layshaft. Notice that the shaft is in the fixed steady - it is essential that the shaft is bored concentric to the kickstart bush in the outer gearbox cover:

Some while back I had left a little excess material on the major diameter of the shaft thinking that I might need to play with the first gear pinion end float, and so it proved. As machined the shaft is a little overlength and I used this setup to remove around 0.020" from the end of the shaft which provided the necessary clearance. 

I'm pleased to say that assembly and testing of the gearbox proved that everything works as expected. The next step, and final step, is to machine the recess for the kickstart lever cotter pin.

Model A - fitting the kickstart pawl

 Back home after a few days away fitting a new front door and frame at my daughter's house in Kent, I find a few minutes to move the kickstart shaft project along a little bit. 

When I left a few days ago I had the shaft set up in the pillar drill just waiting for final adjustment and the fitting of a centre drill to start the hole for the pawl.

That done, we move on to the 9/32" hole on the outside of the shaft. I have discovered that the pin is retained in place by the low gear pinion and cannot come out in service. I bought a pair of long series drills for this job and it makes it a little easier to set the work up on the pillar drill. We go right the way through both sides with this one:

We follow the 9/32" with a 5/16" drill which only goes through the inside web. I'm pleased that the pin fits very well in these two holes and with a little fettling (the pawl was rather ragged) the pawl goes in as well.

I'm a bit concerned by the shape of the pawl where it engages the pinion as the surface, perhaps not surprisingly, is rather worn. A further problem is that the cam which pushes the pawl back into place actually jams the shaft. This is due to the lack of wear in the new shaft I think since dimensionally it is identical to the old one.

Working on the pawl a little to square it up and refine the edges sorts out the problem and we have a pawl that goes nicely into the retracted position:

The video shows it working in both positions:

A dose of heat and a pot of case hardening compound will give us a pawl that fits and has sharp edges giving it plenty of life. We'll have to see if it still works with the bush in place - that might require a bit more fettling, so we will leave the case hardening until that is done.