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 didn't really understand why you would design a bearing with mixed balls and rollers. The combined intellect of the Raleigh & Ariel Owners Clubs taught me that the rollers are there for axial stability, but the balls reduce friction - the idea being that the ball to roller friction is less than the roller to roller friction would be.

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: 

FH - gearbox

 First off let me just say that I'm not going to rebuild the GB gearbox on the Huntmaster just yet. The gears select well, there's no play in the mainshaft, no lateral play in the gearbox as far as I can tell and whilst there's a little bit of movement in the sleeve gear it's no worse than other gearboxes I've looked at at the outset. Turning the shaft by hand doesn't reveal any strange noises so I think we'll just leave it be for the moment. 

However, there is something strange going on. When I assembled the clutch I discovered that I couldn't get the plates to touch, even when the screws were done up relatively tightly against the springs which made me think that perhaps there were two ball bearings within the main shaft. I fitted a new one when I replaced the push rod but now that the pushrod assembly is effectively over long I think there may be two. 

Of course I can't remove the ball bearings from the clutch side because they are right down at the other end of the mainshaft and I've no means of pulling them out. Therefore I've got to remove the kickstart case cover, have a look at the clutch mechanism and remove the balls from that end. This will give me a chance to polish the kickstart case cover to match the timing cover. Secondly it will give me a chance to look at the mainshaft end float and to learn a little bit about the gear selector mechanism on the GB, which I've never looked at before.

The kickstart quadrant is in lovely condition:

It looks very clean inside and it's immediately obvious that the design is a little more sophisticated than the BA/CP type that I'm used to. The mainshaft has no detectable end float that I can find. It's obvious that the gearbox has only had oil in it; though I will probably use the Morris K400EP grease in it as usual.

Moving the pushrod from the clutch side, having pulled the lifting mushroom out revealed something rather strange. There's a large lump of what appears to be oily rust sitting at the end of the main shaft:

I pushed this out and then ran a little roll of paper up and down the inside of the mainshaft swabbing out the remaining muck. It was at this point that I realised that the quarter inch push rod that I had made in a previous post is the wrong diameter for the GB gearbox. Speaking to the various members of the club, including the gearbox specialist, revealed that GB gearboxes use a 5/16" diameter push rod. 

While waiting for some new bits to arrive I'll polish the end cover:

FH - preparing the clutch

 Next up after the primary case is the clutch. I have the whole clutch that came with the FH kit but I've not had a look at it yet. Let's see what we have.

First of all let's have a look at the clutch centre. As expected and like most Ariel clutches that I have seen the grooves in clutch centre that carry the plain plates are deeply notched. This is useless and will have to be replaced otherwise the clutch will never release cleanly.

The rest of the clutch though is pretty good if greasy. First of all I'll clean it in paraffin tank and set it aside to dry for a day or two.

Meanwhile I bought a few bits from the AOMCC gearbox spares specialist. This includes a new clutch centre spring studs set screws for the basket and a couple of tab washers, and as usual the parts are available at a good price, are delivered very quickly and are very good quality:

When the parts I've washed are dry I've wiped them over with a blue paper towel. The clutch basket, which is of later type with friction material riveted to the basket responds well to an additional clean in a solvent.

Charlie's Shed - clutch holding tool

 One of the problems that you can have when you're working on a bike is trying to undo nuts from components that spin around such as the clutch or the engine sprocket. 

Today I'm going to show you how I make a tool out of two clutch plates to hold the clutch in place while we undo the centre nut or conversely do it up again. 

Regular readers will know that I've built several clutches over the last few years and have a number of old clutch plates knocking about. To start with I've taken a friction plate and removed all the old worn cork inserts. Then I've added a plain plate and placed the two over the top of each other in the way they would appear in the clutch using the TIG welder to fasten them together.

Once you've got your two clutch plates together you'll need a handle - there's no point having the clutch basket and centre fixed together if it's still going to spin. In my case the handle is made from a piece of old door threshold - effectively a rough piece of 20 mm by 5 mm flat bar. I've used the TIG to place a fillet weld around the base of the flat bar and attach it to the clutch plate assembly.

I used the TIG torch to heat the handle and form a local bend as an experiment. The problem I have with forming hot bends by my usual approach - a MAPP torch - is that the heated area is so big, the bend is anything but sharp; OK if you want it like that, but this one needs to be in just the right place.

It's worked rather well I think. Here you can see it in action, helping put the FH clutch together.

Gearbox Done

 After spending the winter rebuilding the gearbox and the clutch, I'm pleased to be finishing the job as the weather warms up.

First job, before finally closing up the gearbox is to fit the kickstart stop rubber that has been waiting on the bench for literally years. I needed to remove the metal part of the stop and reduce the 1/2" OD to about 7/16" to get the rubber to go over it. I mangled one in the process of realising that, which delayed the job by a week:

Next, when the kickstart is on and the gearchange mechanism is timed, I need to fill the gearbox. This is easier said than done as on a SQ4, the filler is hidden behind the oil pipes. Surgeon's forceps are useful to get it out:

Since the Morris K400EP grease is quite fluid, the easiest way to get the grease in is to use a syringe. This is a 250 ml syringe and you need 750 ml. It's got a flexible hose and a rigid copper pipe on the end to get the grease through the filler and into the top of the gearbox. You can fill the syringe by sucking the grease out of the tin:

Next time i do this, I'll do it warmer weather. This was hard work:

In a departure from usual practice, I've measured the oil going into the primary case - 150 ml of engine oil, to determine how much I can get in without it leaking.

I'll road test it, then see if 150 ml is too much or not enough.

Running the engine on the rear stand shows I can select all gears completely silently. It's never been as good as this:

New Clutch Plates

Are events coming back to bite us? In this recent post I commented on some intermittent clutch problems - maybe we are now finding the cause.

Three of the four plates are like this, and the colour reveals they have been hot:

This is a new set from AOMCC Gearbox spares, laser cut, a realistic price and flat as a pancake.

We are getting near closing up now. All I need is a kickstart rebound stop, which is coming from Draganfly, and I can refit the kickstart and the gearbox end cover. Then I can test the kickstart and set up the clutch.

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.