So, after a grand day out, with a picnic, we were heading home and having left the speed restrictions of Blairgowrie were heading towards Meikleour (Muckcluer) down the A93 that has a couple of long straights. At the end of the 50mph limit on the first straight, I opened up the Duke and overtook an Army lorry cruising at his 45mph limit and her singing along between 60 -70mph through a left and right dip and onto the next straight, when there was a noise like your visor vibrating, when the wind gets between it and the helmet. I was sure it was secure, checked and all was well. But that “Brrraaap!” had me worried and decided to turn right off the A93 at the x-roads into Meikleour. I stopped to let oncoming traffic pass and then turned right. The clutch was still working, but was a bit harsh and I took a look down to my left. My boot was running with oil, the whole of the left-hand side of the bike was covered in oil, there was a piece of the outer case attached by a bit of flapping gasket and the clutch adjusting cover plate was smashed at both ends and bent, with only one countersunk head screw holding it place.
Kat, on the Bros, had a film of oil droplets all over the front of the Bros and herself, apparently this had appeared at the start of the second straight. So the Duke had covered about 2 km (1.3 miles), with oil coming out of the cases. The clutch had operated on 6 occasions and was still driving. Whilst the engine hadn’t missed a beat!
So, nothing for it, but to push the bike down to the Meikleour Arms car park, have a pot of tea and shortbread; await recovery to home, whilst Kat rode home once the recovery had been arranged.
Today, I started stripping and cleaning the engine and the bike and from the attached images you can see the carnage. It would appear that there has been a long time fracture at the bottom of the clutch spring screw retaining post in the bottom of the clutch hub and after 85,000 + miles it had enough and “let go”! Punching its way sideways, having caught the edge of the outer case and making its exit from the case, along with the retaining screw, washer and spring still affixed, never to be found.
At first I thought that the retaining screw had become slack and ejected itself along with the washer and spring. But, it was after removing the pressure plate, with mangled spring cup in situ and the clutch plates that the true culprit, the clutch spring screw retaining post, was revealed.
So, I will now be having a look through the “useful bits”, speaking to some engineers, to see what might be salvaged, how big a strip down will be required (the out-rigger bearing has alloy flakes in it and is “lumpy”). There were very few little alloy shards within the case and none came out from the sump when the oil came out. The engine turns freely and there is no excessive play between the helical gears and no end play on either the crankshaft or the mainshaft. So, I think that the oil pump will need a strip and inspection to see if there are any marks on the pump gears. If there are no marks, I think that the crank could stay in situ. A flush out of the sump with brake cleaner and a sweep with a flexi-magnet and then a rebuild, would be a nice option.
Has anybody else experienced this failure, under any circumstances?
Would you strip the motor and split the cases!
I am just thanking the fairies that the bits didn’t get ingested and lock the primary drive at 60mph +!
Good health, Bill
So, I shall be delving into the guts of the oil pump and swilling out the sump. After which I shall probably have a quiet chat with a soothsayer, who after much sucking of teeth and pondering, may opine the quality of my scrap metal!! 
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