Cranky Clutch, Simple Seals (Part 2!)

Finally, Mark’s TX clutch gets finished!

- Mark Haycock

Continuing our TX500clutch examination, when we look at the components we can remind ourselves that the clutch works by having the outer driven by the engine, and the inner drum mounted on splines on the gearbox shaft to form the output. The intermittent connection between these two components is through a multi-layer sandwich of two types of plates being squashed together.

The outer needs to rotate freely on the shaft and in the TX500 that is by means of a plain bearing using a hardened steel bush on the shaft with an accompanying thrust washer (Photo 1) and a phosphor bronze bush within the outer (Photo 2): these looked normal and the outer rotated freely so no problem there.

Now the plates: the driving plates (Photo 3) have composite faces and the thickness needs to be measured to make sure they are not excessively worn. The allowable wear in this case is only 0.2mm. One point was what appeared to be scrape marks on the outer tags and I confess I don’t know what has caused this but I cannot see that this would be related to dragging.

The driven plates are plain steel and they must be flat as any bowing will take up free space and lead to dragging. You are meant to carefully check each one by trying to insert a feeler gauge into any gaps all round when it is placed on a surface table. You are unlikely to possess a surface table so a sheet of plate glass will do. I don’t bother with all that: you see how they are stacked in this photo? (Photo 4). Just hold them up to the light and check to see if there are any tiny gaps. Of course, it could happen that they are all bent in just the same way and so there would be no gaps but seriously… If you want to double check then move them all round a little bit in different directions.