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Corking an ES2 clutch

posted 25 Dec 2011, 04:38 by NOC NSW   [ updated 7 Dec 2012, 16:02 ]

Re-corking a clutch is idiot simple. No special tools are needed, you don't cut out pieces of cork or anything. You don't use a punch. If you look at the clutch plate you will see the cork holes have a taper. What you do is buy ordinary bottle corks. You buy the size that is about an 1/8" (3-4mm) longer than the hole in the clutch plate and about 1/8"(3-4mm) wider across. In other words, just too big to go in sideways.

You then wander in to the kitchen, smile at the domestic manager, take a large saucepan half full of water and heat it up on the stove. When it is simmering just under the boil you chuck all your corks into it. You will see they all float on the surface which is why you only have the saucepan half full. You let them simmer until the corks go quite soft, about ten minutes or so. You can then pick them out one at a time and push them sideways into the clutch plate. Cork is an excellent insulator so although its been in very hot water you can do this with your bare hands. When you have put a cork in all the holes in the clutch plate you put the plate aside and go and have a beer. You might even pour out the water and put the saucepan away if you want to keep the manager happy. It will not have got dirty in any way from the corks.

Next day when the corks are completely dry you will find they have gone firm again and are solidly set in the clutch plate. You now go back to the kitchen and get the managers sharpest kitchen knife. You then kindly sharpen it for her and test it out by laying the clutch plate on its side and carving off the excess cork until you have it roughly shaped how it would look like in the bike. You need a really sharp knife for this.

Now is the technical part out in the garage. Using a disc sander or grinding wheel or whatever you have you grind the corks down to size nice and flat and parrallel with about a 1/16-3/32" proud of the plate. With very little practice you can do this freehand, by eye, without any trouble at all. Forget all the rubbish about carefully doing this in a lathe with a specially sharpened tool, etc. Cork is flexible, any minor errors will be absorbed by the cork when you reassemble the clutch. Be careful when you grind the cork, it is very soft and you barely touch it on the abrasive surface. Its like grinding butter.

Depending on the local availability of corks, home brew shops can be helpful. Only use solid corks, not reconstituted or granulated cork and if you use cut down wine bottle corks don't use the ones that are glued together in layers. There you are, how to recork a clutch in the kitchen.

Villiers Bob