Square Four - another clutch

 Well, I recorded in my last post that the Square Four clutch was slipping badly, so badly that as I rode it up the hill back to the workshop the engine speed was soaring and it was clear that the clutch was on its last legs.

I've said many times before that these bikes are very easy to work on. One thing I've always done when accessing the clutch is removed the footrest - but actually don't need to do that. All you have to do is remove the nut and rotate the footrest on its mounting out of the way - you don't have to break the taper at all.

Even before I dismantled the clutch it was clear what happened - you could smell the burnt cork and there were bits of it everywhere. Stripping the clutch down revealed carbonized cork inserts - I could put my finger through these and they would just disintegrate.

Fortunately I had a spare set of 90 corks - that's enough for three plates - sitting in the workshop. Once I'd spent a couple of hours cleaning the mess off the plates I put these in boiling water for a few minutes.

You can push them in with your fingers - or a bit of wood is sometimes useful. It does make your fingers hurt after doing all of them, but it doesn't take long really.

I thought there was one missing - so I rescued a wine cork from the bin.

It's easy to slice these up into the right shape.

As it happened, as soon as I started clearing up the plastic bowl I've used to soak the corks I found the missing one so I didn't end up using my homemade one.

A couple of hours work had all the plates re-lined.

When you put new corks in, I always fit them to the bike wet. When you initially fit the plates they will only just be retained by the basket slots but the next day you will find they have settled a lot. You can see in this picture that the first friction plate is now well into the slots - this is about 24 hours after reassembling the clutch and all the corks are now dry.

I tested out a couple of days later, and readjusted the cable. The bike started straight away though as normal the clutch was stuck - I have always had to free the clutch before starting this one.