Having finally got my Darmah to the state where it (seemed to be) safe to ride, I took it for a 30 mile run last week. On my return I noticed that the rear tyre was covered in oil which had leaked from the final drive onto the chain and thence onto the tyre. Luckily, I hadn't banked hard for any right-handers or I wouldn't be typing this now.... On closer inspection I saw that the 'castle nut' which holds the final drive on was loose and this is likely how the oil was escaping through the splines of the shaft. It turns out that whoever 'restored' this bike tried to tighten this nut with a cold chisel instead of using the correct special tool - with predictable results. So, having sourced the correct tool and a new nut and star washer, I am now in a position to right the previous wrong and make this SD a bit less of a death-trap. However, whilst the star washer does have a tab on the inside to engage in a slot to stop it turning, there's no slot to engage it in. The only way to get the start washer on is to bend this tab back and then there's nothing to stop the washer turning, an the nut with it. Am I missing something here?
Can't help with the lack of slot in the output shaft, but this on ebay might help. No. 163901484252 Mine regularly came loose on my SS from new no matter how it was tightened and irrespective of the lock nut. Also tried super loctite and it just loosened slowly but still came loose
From memory the tab on the inside of the lock washer is quite small and needs a little 'persuading' into a decent perpendicular shape (backwards from the washer) to allow it to be fitted into one of the slots in the sprocket. I'm not sure if that's how it should be done but it worked for me. So when refitting the order is the machined spacer first, which will protrude a little from the seal, a gentle smear of blue hylomar on it's & the sprocket's mating faces. Sprocket on, washer next with the tab in a sprocket slot and then the sprocket castle nut n.b the latter should have the flat side facing outward. And then tighten it as tight as you can, Ian Fallon's book has this at 87 - 95 ft/lb. You may well have to stop short of that to allow a washer tab to line up with a slot.. Other solutions are to have 2 castle nuts & there is a nyloc nut available see https://www.ducatiforum.co.uk/threads/1980-darmah-900-ssd-in-france.101780/page-15#post-2237876 Btw - you may also need to check the leak isn't coming from either of the seals, the large one around the output shaft & the small one at the end of the output shaft.
Having said that I'm now wondering if the star washer can/should be threaded onto the output shaft and this will somehow lock it
Thanks for this. Just had another go and, sure enough, you can secure the washer from turning by getting the tang into the end of a spline. A bit Heath Robinson, but it should do the trick. I've ordered a Nylock version of the nut as well and will spin this against the other nut as an extra insurance. I might still check this on a regular basis though as it won't be pretty if it comes off at speed....
Nice... luckily it doesn't just fly off without any warning. Any oil in the area is an indication it's starting to come loose.
