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 to 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.

FH - fork drain plugs

Another little job today - fork drain plugs.

These are just 2BA cheese head screws cut down to about 1/4" and provided with fibre washers:

To give them a better chance of retaining some fork oil, I've loaded them with Loctite 577 thread sealant.

 The other thing that I need to remember is that I need to find 7.5 fl oz of SAE 30 oil to put in each fork leg.

Also in the news today - the right hand tank knee rubber is now on, I've tightened some more bolts and I've scraped enough paint off to allow the petrol tank cap to fit.

Burman Clutch Centre

 Over the last few days I've assembled the primary drive and the clutch, tightening the mainshaft nut in the process.

I've installed the clutch spring studs with Loctite 271, the red thread locker. That won't come loose; originals were peened in place, but it's not 1950.

Fitting the plates revealed some rocking. I pulled them all out again, and found that three of the four plain plates were distorted by up to 2 mm, and discoloured from heat.

Geoff will send some new ones tomorrow.

Charlie's Shed - adapting threads

The FH kit came with a lot of original Ariel cables, most of which were pretty rusty but which still had their original adjusters and nipples. The cable layout changed with the advent of the swinging arm bikes, in that the mid-length and gearbox end adjusters moved up to the handlebars for the front brake and clutch. The thing is, most of the handlebars out there use the later 5/16" BSF adjusters, but Ariel used the earlier 1/4" adjusters to the end. Guess what? Levers with 1/4" adjusters are like hen's teeth!

So what to do? after looking at eBay for ages, and noting that Draganfly are out of stock I decided to modify what I had by sleeving the existing 5/16" thread. The issue is that putting a 1/4" thread inside a 5/16" thread leaves very little wall thickness, so the part would be weak. Here's how I set about it:

First job is to turn a bit of scrap brass to the correct OD - 5/16", and put a thread on it - these are BSF threads in these levers, by the way - so it's 5/16" x 22 tpi. Next, we can drill a hole, tapping size for 1/4" BSF, but we won't tap it yet. Next we can try it out in the lever perch and if all is well retain it with some Loctite 263 high strength thread locker:

Next job it to file the ends flush, and tap the hole. Currently I don't have a tap long enough to go all the way through, but it's long enough for the adjuster. Cut the cable slot with a hack saw and a needle file:

Job done!

What's that ominous noise?

Last weekend, my Sunday morning jaunt ended after 1.5 miles with a screech/rattle (strange sound in between the two) that has appeared while accelerating up a hill. I think it's transmission - out of gear the engine appears to be fine. Turning the rear wheel by hand with the clutch out and the bike in gear sounds rattly - I think I will have to take a look at the clutch. The noise changes with clutch operation, less harsh perhaps and appears to be related more to road speed than engine speed.

Of course, as I write this I sound like I have a misplaced confidence that no Square Four owner has any right to - you are always worrying that it is going to lift it's skirts above it's knees and show you a connecting rod when you were least expecting it. This time, I arrived home with the engine ticking over sweetly and it continued to do so when I parked up. 

Running it on the stand, I couldn't replicate the sound, but I did notice the rear wheel is a lot more wobbly than it was when I built it.

A week or so later, after some busy time at work and contemplating that I might get the CX500 on the road, I found a bit of time to pull it apart. It's worth remembering that older bikes are often easier to fix than newer ones - my Square is a lot less complex than the Honda and it's much easier to work on.

All I need is this handy kit that I found in the bike's toolbox:

Or - not. Falling at the first fence, I found that I did not have a 3/8" AF box spanner in the tool roll. This odd ball size fits not only the clutch centre screws but crucially the exhaust pipe clamps - so I couldn't even start the job. I made a note to buy one for the tool roll.

With the pipe off, I slackened off the brake pedal and disconnected the brake light - that lets you remove the clutch dome. I might see if I can get a better shine on that patina:

With the right tools, the clutch plate came off perfectly:

And it revealed a loose clutch centre nut, just as had been predicted by the AOMCC forum panel of experts. The nut was loose but still in place, but it probably wouldn't have come loose at all if I had been a bit more thorough with the tab washer:

Watch:

The clutch plates are getting thin, but I have no wish to re-cork them right now, nor any cork; they need pulling out with this bit of hooked wire I keep in the tool box:

Slightly sticky. That's grease from the centre bearing:

Here it is again - we will have to be sparing with it on reassembly. The splines are no worse than when they went in back in 2014:

And again. Those screws are in place but very loose:

As can be seen in this video:

Thankfully, all looks well under the primary chain cover:

The shock absorber nut is exactly as it was when I fitted it back in 2014:

Sprocket looks fine:

Having removed the chainwheel and carefully removed its bearing (with the twelve needle rollers) I set about removing the rear half of the chaincase. When it wouldn't come free, I remembered that the rear upper chainguard is bolted to the chaincase and that the bolt lives under the battery. This has not been off for ages as it has been no trouble at all:

Here's the bolt I'm talking about. You have to remove the coil as well:

Once behind there all looked fine & dandy:

Oil filter head looks OK:

At close of play, the rear chaincase was back in place, sealed with Threebond 1215:

The next day I tensioned the primary and put the chainguard and the coil back in place, and the following day I put the primary case back together:

Next came the clutch rebuild. This time I paid much closer attention to assembling clutch basket to the sprocket, and the centre to the mainshaft retaining both with Loctite 243.

The mini-lathe is a useful beast. Here I'm turning up a new spacer to fit between the primary chaincase inner half and the frame in stainless steel. It's 1/2" long, 11/32" ID for clearance on a 5/16" bolt and 3/4" OD:

This is the truly awful side stand. I never use this, as it is far too short and consequently precarious. The tie wrap is there to make sure the spring cannot become disengaged from the lug on the leg, which would leave the leg flopping about:

Assembling the battery carrier and it's spacers:

And all back together.

Loctite 577

Remember the weep at the end of the rocker shafts? I've applied Loctite 577 thread sealer here, which should fix that problem.

Once we fix that leak, we can look for others...

The head is on!

So we are all set. The sun is shining, I have a day free (after cutting the grass and making the family dinner) and I have all the parts, plus a very nice text from Bruce Longman via Draganfly with explicit instructions. Max is in bed, so he will be happy for a bit:

A Chocolate Sprocker, feeling very 'Sunday Morningish'

I have some high temperature silicone gasket as recommended by Bruce. Loctite say this is suitable for operating temperatures up to 275 degrees C (sustained) with excursions to 300 C:

So as recommended by Bruce, we start by laying a band of sealant around the pushrod tunnels, on both sides of the gasket. Actually easier to lay one bead on the gasket, and one bead on the block, making sure you have the handed gaskets the right way around:

No picture, but next I placed all the head nuts in position between the cylinder block fins, under their holes, with the flanges upward. Next, manoeuvre the head under the frame tube and drop it into place over the studs, making sure the extended, rounded ends of the studs drop into the nuts. Add the sleeve nuts inside the rocker boxes, and the 5/16" CEI reduced hex nuts outside the rocker boxes. You hand screw these down finger tight.

And as Kees Knegt pointed out in a comment to an earlier post, this would have been easier without the rockers! You cannot fit the pushrods with the rockers in place either (they don't slide sideways far enough) so I may as well have left them off... although I do like to trial fit everything at least once.

Next, with your thinnest 5/16" CEI open spanner, engage all the nuts on the downward facing head studs and turn them as far as they will go without using and force. You will realise now that if you leave one undone, and tighten the others, you will crack a fin by virtue of the loose nut pushing downward onto the fin below.

Once you have all the nuts finger tight you will see the head finally come down onto the gaskets. continue going around all the nuts inside & outside the rocker boxes until they are all snugged down finger tight.

You will need a variety of spanners to achieve this. The reduced hex nuts in the middle of the head, under the inlet tract are particularly inaccessible.

So, when everything is snugged down, use Bruce's torque figures and sequence to tighten down the head.

Job done.