I find I have a missing pin (sheared or worn off) on the clutch boss (I.E. hub); Can anyone tell me, what are the consequences of a missing pin which locates the clutch spacer in the clutch centre boss? Ducati p/n 742240570 SIze 2.5 x 10mm I suspect the to stop rotation of the spacer, and hence also the o-ring sitting in the spacer. Perhaps this can be a cause for oil leak? The spacer is torqued down under the clutch nut, and might find it hard to rotate for that reason, but anyway Ducati think fit to include the pin. See the pin here, item No. 34 in diagram: https://www.bike-parts-ducati.com/d...port/1997/900_SS/900-SS/CLUTCH/745/2302/0/745 Cheers, John
Nice one Chris! Found you, the right person straight away. I'm lucky. Interesting write up. Tells me what I suspected. But not perfect: "It sits between the clutch slave piston and the clutch pushrod." << rather vague, or simply incorrect depending how you look at it. In fact it sit just as I say above. "Its job is to stop the pushrod (or piston interface) from spinning when the clutch is actuated." << True, it MAY stop the pushrod spinning, but that would be only stopping the spacer spinning, through which the pushrod passes. It states: "rotation can spin the clutch piston and cause the seal to leak.” >> I think actually it is not a clutch piston (there isn't such a thing) but a clutch slave cylinder piston. The article speaks in general of loss or contamination of hydraulic fluid, and of general seal wear. I wondered specifically if it would permit rotation of the spacer and hence the green o-ring seated within it. no such oil loss is mentioned. I conclude that, if the spacer spins, yes it would compromise that seal, which is not a seal for rotating shafts anyway. There are some good points on the consequences concerning grooving, heat build-up. Also clutch actuation - notchy or inconsistent clutch feel, pulsing and binding.. AND most importantly: it keeps the actuation purely linear (in/out); In effect, it converts the system to an “anti-rotation” type clutch actuation, similar to later Ducati designs. Problems with chatgpt/AI in its compilations are to be expected. Mainly because it is not intelligent, and doesn't know what its talking about. All the good stuff is harvested from lines from forums, and weighted for likes etc... some grammatical re-ordering, redundancy checking etc. A sort of sophisticated search. Can be misleading. Poor visualisation of the layout, and as a fixing. Would get a fail because it's cribbing from online publications. John
Conclusion: The pin p/n 742240570 locates the clutch spacer in the clutch centre boss; Pin size = 2.5 x 10m, stops the clutch spacer from spinning out of sync with the clutch boss as it turns. It is not equivalent to anti-rotation insert, found in later models. Edit: Corrected, as per Nelly's suggestion, and my own reflections since. John
It’s in there to prevent the spacer from spinning and thus the clutch drum nut coming undone. It’s nothing to do with the pushrod. The anti rotation pin mentioned is fitted in later bikes at the slave cylinder end to stop the pushrod spinning. Your bike is too early to have this version. I’d get the pin replaced and prevent the risk of the clutch assembly coming off
If you find ChatGPT is wrong then tell it. It cannot learn itself but can be improved by those who administer it. It is called Reinforcement Learning from Human Feedback (RLHF). I added @nellys post and got this result. https://chatgpt.com/c/69ef240e-3434-83eb-8c7c-463bd17a91a9 Adding the model year in this case would probably got a better answer than just the part number.
Thanks Nelly I beliieve you are correct - relised this is the case as I continued installing my pin. I've corrected my conclusion above. I did order a pin and, after drilling out it's old place on the boss on centre to a depth of 7mm with a 2.5mm drill bit, successfully installed the boss with a firmly set roll pin! I would say that no more than 3mm should stand proud, and not much less, looking at the spacer. Its very important to drill on centre to match the hole in the spacer. Not terribly easy to find that point. You might try drilling out by using the spacer as your guide, but as the hole is slightly shrouded, it would need opening up first. I managed without that, but it's touch and go to get it on centre. Roll pins are sized by the diameter of the required hole, i.e. a 1/8" roll pin will fit tightly in a 1/8" hole; The pins themselves are 'oversize' in the relaxed state.
That's a good idea Chris, but would say it is not my cup of tea; I believe in personal tutors are generally essential or can be useful, alongside learning by doing and observation, with specialised forums or guilds to keep tidy well-honed notes -E.G. our 'Stickies' and the similar for other marques. Chat GPT depends upon such forums and their work, i can never replace them. So I dont see the point of serving ChatGPT & Co.
Incidentally, Nellie, ChrisW, RoyalM. What do you think is the job of the 7.66 x 1.78 o-ring which sits over the pushrod within the mainshaft after a single-lipped springless seal ( 8x12x3) covering the small pushrod needle bearing? That lipped seal is to stop oil emerging from within the shaft, I take as granted. I must say, the o ring looks good there in green And, Is it meant to get pressed slightly by the thrust bearing when clutch is engaged? (If so, that would depend upon stack height within its' 0.5mm or so tolerance).
That's interesting, and the idea surprised me. Think you may be onto something there Chris. It's a nice cushioning touch there at the bearing and seal then, as the rod extends into a thrust bearing. Especially when disengaging, I imagine.
