When I was dismantling a '76 engine, in the filter trap and around it there was loads of clutch friction material, along with piles of other garbage.
When I dismantled the clutch, here was the reason!
In the middle of the clutch pack there sits the most horrendous piece of engineering which Honda call 'Plate B'.
It's a clutch damper, two plain plates which sandwich a number of spring steel strips between them to give a cushioning effect to the clutch action.
The steel strips are held by TINY BRASS rivets, one end of each strip rivetted to one plate and the other end to the second plate.
As the strips flex the rivets are either worn through or pulled out of the plates. If you check the above pic you will see the result.
In these pics you can see the results of the one strip which came completely out, ripping into the clutch plate friction material, and another that is only held by one end!
This one on the left shows the components.
As you can see from this picture, when bits of rivet get into the clutch oil scavenge pump, which can easily happen, the pump will jam and cause all kinds of damage; plus the errant steel strip could jam the clutch or the oilpump drive chain etc.
I can't even see the reasoning behind having this abomination. There is enough slack in a chain primary drive to give some cushioning plus the output shaft has a spring shock absorber, so this just seems like overkill to me.
So, if you've got to do the clutch, do yourself a favour and heave this thing into the nearest bin.
Of course, that then leaves the clutch pack short of the thickness of the damper.
Easily remedied! The plain plates are just a tiny fraction thinner then the damper, so purchase two extra plain plates, but be careful where you fit them.
One goes into the centre of the clutch pack, in place of the damper plate, the second is fitted at the back of the pack.
It needs to go here, directly onto the spring carrier. This is double good as it provides a steel surface for the first friction plate instead of the alloy of the spring carrier.