First, the original clutch corks seemed to be worn, so I ordered exchange plates from Villiers Services.
I re-assembled the clutch with the new plates and took the bike out for a test ride, but the results were not good, when the clutch lever was pulled in the clutch seemed to drag, making it difficult to get the bike into first gear, and no adjustment that I could make made any improvement.
Back to inspecting the clutch, and I observed that the clutch plates appeared (note the word 'appeared') to be lifting unevenly, so I checked that everything was square, particularly the top of the 'penny on a stick' push rod, and the surface it pushes on to. It all seemed perfect.
Perfect, that is, until I decided to run the engine with the chaincase cover off. Then I could see that, with the clutch engaged, the outer plate was wobbling significantly, and when I pulled the clutch lever in the outer plate lifted and then ran true.
So I checked the corks in the exchange plates I got from Villiers Service and I found that those on one side of the chainwheel differed in thickness by around 1.3mm from the corks on the other side and the other set of corks varied in thickness by about 0.3mm. Bearing in mind that the clutch pushrod lift is only around 1.5mm I concluded that the clutch drag problem was caused by one side of the clutch not being lifted out of contact.
Also to add insult to injury some of the corks were loose, one popped out with just a push from a little finger, and all of the corks were thinner than the dimensions specified in the service manual.
The exchange plates were not satisfactory.
I decided I could to a better job myself!
I researched the topic of recorking clutch plates on FBOC and 'andy4205' sent me a PDF file to get me started, here is the link...
I bought 1/2" thick cork sheets from charlescantrill.com
Using the info from the PDF file I made up my own cutting jig for the corks...
For cutting the strips the pillar can be removed, different pillar diameters change the width of the cork. It took a couple of attempts to get the depth of the slot right.
Having cut the corks I softened them by simmering for 15 minutes, letting them soak for an hour and then reheated the water to near boiling point.
The corks were very tight to insert and on the chainwheel particularly I had to be careful to ensure the amount protruding on each side was equal, as the cork was not much thicker than the required thickness.
Now for sanding the corks true and flat, and for this I made up custom fittings to hold the clutch plates on the chuck of my Myford lathe and a sanding attachment for the tail stock. I couldn't think of any simpler way of sanding the corks with any degree of precision.
The sanding medium is self adhesive (not Velcro) 320 grit.
As a final adjustment I made up spacers of 0.5mm, 1mm, 1.5mm & 2mm thick to fit underneath the springs to adjust individual spring compression to ensure even lift.
I have not yet ridden with new plates but static tests suggest the clutch is now freeing cleanly.
If anyone (local-ish) would like to borrow this kit, or use it to sand their clutch plates at my place they are welcome.
- Posts : 7
Join date : 2016-03-24
Location : Hatfield, Hertfordshire
I have just rebuild an 8E and gave thought to getting some brass cut to replace the corked plates. Not sure how it would work but I am not keen on cork for modern use.
You can get your plates fitted with special inserts or pads.
- Posts : 1806
Join date : 2008-02-11
Age : 66
Location : 1950 Powerbike 56. 1960 Falcon 87. 1961 Trials 83 Special. Falcon 87 in bits. Falcon 81 Trials bitsa.
- Posts : 64
Join date : 2016-08-08
Location : Wolverley, Worcestershire.