Britbike forum Forums British Motorcycle specific Brands Ariel forum Clutch basket abrading primary cover

I removed the clutch cover from the primary of my 1958 Square Four to see why I had some clutch slip. I found a lot of powdery grey stuff in the cover and coating the outer primary cover. The plates were fine and dry but, on removal of the basket, it was obvious that the back of the basket had been rubbing on the outer portion of the alloy cover and it was fine metal (aluminium) powder that I’d seen.

I read the comment on Draganfly”s website in which they mentioned this problem and it suggested I might have too short a mainshaft. However, if I grab the chainwheel I can slide it in and out (towards and away from the gearbox) by about 1/8” suggesting it is more than long enough. When pulled away from the ‘box, it appears to line up with the crankshaft sprocket better and the basket no longer rubs (if I temporarily replace the outer primary cover). I do not see that there should be a spacer or shims behind the chainwheel in the parts book - should there be? Any foreseeable problems if I do fit a spacer?

Thanks in advance.

It is probably time to have a good long look at a gearbox parts book and see what internal mainshaft shims might be missing or of the wrong size.

If I cannot fix the problem by fitting a 0.060" shim behind the basket, I will have to dismantle the gearbox next. Thank you, Stuart

Hi Paul,
Is the main shaft moving with the clutch ? If so the problem should be apparent when you remove the outer gearbox cover
The main shaft is located by the kickstart ratchet nut, the inner ratchet bush and the bearing in the inner cover

Is the clutch centre nut tight?
There is a bronze shim 3394-36 on the shaft adaptor behind the roller race and one with a tab 3397-36 on the outside
If these were missing it could allow the clutch to float about

A note on the needle bearings, those supplied by most suppliers are incorrect at 3/32in. diameter (.093) where as they need to be 0.100in.
This mistake leaves the clutch with 0.014in radial movement
I had some loud disagreements with the "usual" supplier about this when looking for replacement rollers, their answer was "that they will fit"
At the time I had 6 original clutches to check against but they would not accept any correction or criticism

John