Charlie's Shed - Re-corking Cutch Plates

 For no good reason, other than the fact that the Square Four cork clutch is excellent, I decided to replace the part-worn Ferodo lined clutch plates. The W/NG clutch had always felt more severe by comparison and while the Ferodo clutch is correct for the W/NG, sometimes I do stuff because I feel like it!

The plates and corks come from AOMCC Gearbox Spares, and very good they are too.

The first step is to warm the corks in boiling water to make them soft and pliable. They were in the soup for about 15 minutes.

I fished the corks out in small batches with a draining spoon.

These are the plates - they look like they have been laser cut. The edges are very crisp and clean - the holes are perfectly shaped and there are no burrs. Oh - and they are perfectly flat!

You push the corks in from the wide end of the slot, trying to keep an equal amount of cork protruding from the plate on each side.

Push the cork down, and manoeuvre the wide end in until it is sitting evenly all around the slot.

Repeat the process until you have done all the corks in all the plates!

As it turned out, after drying overnight the stack of plates was too thick for the basket.

What you do now is to work each side of each plate against a large flat board covered with sandpaper. This is 120 grit - I rubbed each plate over a couple of times to make sure the corks were level and to take a fraction off each one. Very soon, the stack fitted in the basket.

At the same time, I renewed the clutch springs - also from AOMCC Gearbox Spares. On the left is the old spring; on the right, the new spring. Whilst the old spring is clearly collapsed, the odd thing is that it is the same wire diameter as the new one - springs for a Ferodo clutch should be heavier.

Model A - First Impressions of a Clutch

Isn’t it a bit early to be looking at the clutch on that bike, when you have so many others in the pipeline I hear you ask? Well, yes it is, but a while back I lost one of the tank bolts on the W/NG - you might remember I made a new one; I am diverting myself with lathe jobs as a distraction from all the welding on the QR50, and part of the lathe work is to collect the bits for the gear control on the Model A, and to do that I need to mount the tank - which is another lathe job, as one or two of the bolts are missing - so I need the tank mounting rubbers for that too, and I also want to trial fit the tank on the FH and I have no rubbers...

So what I need to do is to get an order for Jeff Hunter Engineering, who will supply all the rubber bits and what I am going to do is order as much of the rubber as I can, for all three Ariels. And this is where the clutch comes in - the Sturmey Archer clutch in the Model A has a rubber shock absorber in the clutch and this is bound to need some attention:

So let’s have a look. It’s very easy to get to as in 1930 Ariel were not using the fully enclosed and sealed primary drive, and my primary cover is off awaiting time on the welding bench:

Clearly, two of the retaining bolts, springs and spring cups are missing. Those bolts actually have screwdriver slots under that muck.

Under the pressure plate, the basket and centre are very good indeed:

The plates are reasonable too, but I wasn’t expecting Ferodo linings:

The parts list clearly shows a cork lined clutch:

Yet if we look in the Sturmey Archer book from the period, there is a Ferodo option for the three plate clutch. Interesting.

We’ll have to replicate these parts, though I wonder if they have been intentionally omitted. Ferodo clutches of the period can be quite heavy - the one on my W/NG is much less pleasant than the cork clutch on the SQ4, for example.

Still, it will be a long time before we have to deal with that problem.